Agricultural and Biological Sciences › Plant Science

Phytoplasmas and Hemiptera pathogens

Works Count: 29162

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Description

This cluster of papers focuses on the study of plant pathogens, particularly Phytoplasmas and Candidatus Liberibacter species, their interactions with insect vectors such as psyllids, and the impact on various host plants including citrus. Research areas include genome sequencing, pathogen transmission, disease control, and the ecological and molecular aspects of plant-pathogen-insect interactions.

Keywords

Phytoplasmas; Huanglongbing; Xylella fastidiosa; Citrus; Insect Vectors; Candidatus Liberibacter; Psyllids; Pathogen Transmission; Genome Sequencing; Plant Disease Control

PHYLOGENETIC CLASSIFICATION OF PLANT PATHOGENIC MYCOPLASMA-LIKE ORGANISMS OR PHYTOPLASMAS

1995-01-01

Bernd Schneider , E. Seemueller , Christine D. Smart +1 more

The genome sequence of the plant pathogen Xylella fastidiosa

2000-07-13

Andrew J.G. Simpson , Fernando C. Reinach , Paulo Arruda +7 more

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Current status of molecular classification of the phytoplasmas.

1998-03-01

E. Seemüller , Carmine Marcone , Ulrich M. Lauer +2 more

Phylogeny of mycoplasmalike organisms (phytoplasmas): a basis for their classification

1994-09-01

D. E. Gundersen , I M Lee , Stephen A. Rehner +2 more

A global phylogenetic analysis using parsimony of 16S rRNA gene sequences from 46 mollicutes, 19 mycoplasmalike organisms (MLOs) (new trivial name, phytoplasmas), and several related bacteria placed the MLOs definitively … A global phylogenetic analysis using parsimony of 16S rRNA gene sequences from 46 mollicutes, 19 mycoplasmalike organisms (MLOs) (new trivial name, phytoplasmas), and several related bacteria placed the MLOs definitively among the members of the class Mollicutes and revealed that MLOs form a large discrete monophyletic clade, paraphyletic to the Acholeplasma species, within the Anaeroplasma clade. Within the MLO clade resolved in the global mollicutes phylogeny and a comprehensive MLO phylogeny derived by parsimony analyses of 16S rRNA gene sequences from 30 diverse MLOs representative of nearly all known distinct MLO groups, five major phylogenetic groups with a total of 11 distinct subclades (monophyletic groups or taxa) could be recognized. These MLO subclades (roman numerals) and designated type strains were as follows: i, Maryland aster yellows AY1; ii, apple proliferation AP-A; iii, peanut witches'-broom PnWB; iv, Canada peach X CX; v, rice yellow dwarf RYD; vi, pigeon pea witches'-broom PPWB; vii, palm lethal yellowing LY; viii, ash yellows AshY; ix, clover proliferation CP; x, elm yellows EY; and xi, loofah witches'-broom LfWB. The designations of subclades and their phylogenetic positions within the MLO clade were supported by a congruent phylogeny derived by parsimony analyses of ribosomal protein L22 gene sequences from most representative MLOs. On the basis of the phylogenies inferred in the present study, we propose that MLOs should be represented taxonomically at the minimal level of genus and that each phylogenetically distinct MLO subclade identified should represent at least a distinct species under this new genus.

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Xylella fastidiosa gen. nov., sp. nov: Gram-Negative, Xylem-Limited, Fastidious Plant Bacteria Related to Xanthomonas spp.

1987-04-01

J.M. Wells , B. C. Raju , H Y Hung +3 more

Twenty-five phenotypically and genotypically similar strains of a fastidious, xylem-limited bacterium were isolated from 10 plant disease sources including Pierce's disease of grapevines, phony disease of peach, periwinkle wilt, and … Twenty-five phenotypically and genotypically similar strains of a fastidious, xylem-limited bacterium were isolated from 10 plant disease sources including Pierce's disease of grapevines, phony disease of peach, periwinkle wilt, and leaf scorches of almond, plum, elm, sycamore, oak, and mulberry. The cells were single (occasionally filamentous), nonmotile, aflagellate straight rods (0.25 to 0.35 by 0.9 to 3.5 μm). They were gram negative, catalase positive, and oxidase negative, utilized hippurate, and produced gelatinase and often beta-lactamase but not beta-galactosidase, coagulase, lipase, amylase, phosphatase, indole, or H2S. The bacteria were strict aerobes with optimum growth at 26 to 28°C and pH 6.5 to 6.9 and had doubling times of 0.45 to 1.98 days in periwinkle wilt broth. Monoclonal antibodies prepared against the Pierce's disease bacterium reacted with all strains. DNA composition was 51 to 53 mol% guanine plus cytosine, and strains were at least 85% related in DNA hybridization. Sequencing of 16S ribosomal ribonucleic acid related them to the xanthomonads. These bacteria form a distinct group, and the name Xylella fastidiosa is proposed, establishing a new genus with one species in the gamma subgroup of the eubacteria. Strain PCE-RR (ATCC 35879) is designated as the type strain.

Compendium of citrus diseases.

2000-01-01

J. O. Whiteside , S. M. Garnsey , L. W. Timmer

Compendium of citrus diseases , Compendium of citrus diseases , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی Compendium of citrus diseases , Compendium of citrus diseases , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Reductive evolution suggested from the complete genome sequence of a plant-pathogenic phytoplasma

2003-12-07

Kenro Oshima , Shigeyuki Kakizawa , Hisashi Nishigawa +7 more

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Living with Genome Instability: the Adaptation of Phytoplasmas to Diverse Environments of Their Insect and Plant Hosts

2006-05-03

Xiaodong Bai , Jianhua Zhang , Adam D. Ewing +7 more

ABSTRACT Phytoplasmas (“ Candidatus Phytoplasma,” class Mollicutes ) cause disease in hundreds of economically important plants and are obligately transmitted by sap-feeding insects of the order Hemiptera, mainly leafhoppers and … ABSTRACT Phytoplasmas (“ Candidatus Phytoplasma,” class Mollicutes ) cause disease in hundreds of economically important plants and are obligately transmitted by sap-feeding insects of the order Hemiptera, mainly leafhoppers and psyllids. The 706,569-bp chromosome and four plasmids of aster yellows phytoplasma strain witches' broom (AY-WB) were sequenced and compared to the onion yellows phytoplasma strain M (OY-M) genome. The phytoplasmas have small repeat-rich genomes. This comparative analysis revealed that the repeated DNAs are organized into large clusters of potential mobile units (PMUs), which contain tra5 insertion sequences (ISs) and genes for specialized sigma factors and membrane proteins. So far, these PMUs appear to be unique to phytoplasmas. Compared to mycoplasmas, phytoplasmas lack several recombination and DNA modification functions, and therefore, phytoplasmas may use different mechanisms of recombination, likely involving PMUs, for the creation of variability, allowing phytoplasmas to adjust to the diverse environments of plants and insects. The irregular GC skews and the presence of ISs and large repeated sequences in the AY-WB and OY-M genomes are indicative of high genomic plasticity. Nevertheless, segments of ∼250 kb located between the lplA and glnQ genes are syntenic between the two phytoplasmas and contain the majority of the metabolic genes and no ISs. AY-WB appears to be further along in the reductive evolution process than OY-M. The AY-WB genome is ∼154 kb smaller than the OY-M genome, primarily as a result of fewer multicopy sequences, including PMUs. Furthermore, AY-WB lacks genes that are truncated and are part of incomplete pathways in OY-M.

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Sequencing of diverse mandarin, pummelo and orange genomes reveals complex history of admixture during citrus domestication

2014-06-08

Guohong Albert Wu , Simon Prochnik , Jerry Jenkins +7 more

Genome sequences of nine species of citrus, including oranges, pummelos and mandarins, reveal pathways of domestication and provide resources for breeding. Cultivated citrus are selections from, or hybrids of, wild … Genome sequences of nine species of citrus, including oranges, pummelos and mandarins, reveal pathways of domestication and provide resources for breeding. Cultivated citrus are selections from, or hybrids of, wild progenitor species whose identities and contributions to citrus domestication remain controversial. Here we sequence and compare citrus genomes—a high-quality reference haploid clementine genome and mandarin, pummelo, sweet-orange and sour-orange genomes—and show that cultivated types derive from two progenitor species. Although cultivated pummelos represent selections from one progenitor species, Citrus maxima, cultivated mandarins are introgressions of C. maxima into the ancestral mandarin species Citrus reticulata. The most widely cultivated citrus, sweet orange, is the offspring of previously admixed individuals, but sour orange is an F1 hybrid of pure C. maxima and C. reticulata parents, thus implying that wild mandarins were part of the early breeding germplasm. A Chinese wild 'mandarin' diverges substantially from C. reticulata, thus suggesting the possibility of other unrecognized wild citrus species. Understanding citrus phylogeny through genome analysis clarifies taxonomic relationships and facilitates sequence-directed genetic improvement.

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Citrus phylogeny and genetic origin of important species as investigated by molecular markers

2000-06-01

Elisabetta Nicolosi , Ziniu Deng , Alessandra Gentile +3 more

Detection of the Apple Proliferation and Pear Decline Phytoplasmas by PCR Amplification of Ribosomal and Nonribosomal DNA

1995-01-01

K.‐H. Lorenz

Ribosomal and nonribosomal sequences were analyzed to design polymerase chain reaction (PCR) primers for detection and identification of the phytoplasmas that cause apple proliferation (AP) and pear decline (PD). A … Ribosomal and nonribosomal sequences were analyzed to design polymerase chain reaction (PCR) primers for detection and identification of the phytoplasmas that cause apple proliferation (AP) and pear decline (PD). A ribosomal primer pair (fU5/rU3) was developed that initiated amplification of the target DNA from all 42 samples from PD-infected pear trees and 36 samples from AP-infected apple trees. These primers also amplified rDNA in all other taxonomically different phytoplasma strains that were tested. A pair of group-specific primers (fO1/rO1) derived from the 16S rRNA gene was identified for detection of the closely related phytoplasmas associated with AP, PD, and European stone fruit yellows. PCR detection of the PD agent with primer pairs fU5/rU3 and fO1/rO1 was considerably more sensitive than microscopic detection using the 4'-6-diamidino-2-phenylindole fluorescence method. A more specific ribosomal primer pair (fPD/rO1) amplified phytoplasma rDNA in all samples from infected pear trees but showed some cross-amplification of AP rDNA. Restriction enzyme analysis of the PCR products obtained with primer pairs fO1/rO1 and fPD/rO1 distinguished the AP and PD phytoplasmas. One pair of ribosomal (fPD/rPDS) primers specifically amplified DNA of the PD phytoplasma but from only about 80% of the infected pear trees. Three pairs of nonribosomal primers amplified phytoplasmal DNA from AP- or PD-infected trees or from both phytoplasmas but failed to detect all strains of either of the two pathogens. These results show that is not possible to detect all strains of the AP and PD phytoplasmas, respectively, with pathogen-specific primers.

Development of a Polymerase Chain Reaction Protocol for Detection ofXylella fastidiosain Plant Tissue

1994-01-01

Gerald V. Minsavage

A 7.4-kb EcoRl fragment of genomic DNA of Xylella fastidiosa strain PCE-RR (ATCC 35879) was used as a probe and was conserved in 18 strains of Xylella. The nucleotide sequence … A 7.4-kb EcoRl fragment of genomic DNA of Xylella fastidiosa strain PCE-RR (ATCC 35879) was used as a probe and was conserved in 18 strains of Xylella. The nucleotide sequence of a 1.0-kb internal EcoRV portion of the fragment was determined, and oligonucleotides were selected for primers that amplified genomic DNA specific to X. fastidiosa in 33 strains tested by the polymerase chain reaction (PCR). Plant extracts for PCR -and enzyme-linked immunosorbent assay (ELISA) were obtained by maceration of grape petioles and by vacuum extraction of citrus stems. Known cell numbers of X. fastidiosa were added to the plant extracts contained in a succinate-citrate-phosphate buffer prior to assay [...]

Phytoplasma protein effector SAP11 enhances insect vector reproduction by manipulating plant development and defense hormone biosynthesis

2011-11-07

Akiko Sugio , Heather N. Kingdom , Allyson M. MacLean +2 more

Phytoplasmas are insect-transmitted phytopathogenic bacteria that can alter plant morphology and the longevity and reproduction rates and behavior of their insect vectors. There are various examples of animal and plant … Phytoplasmas are insect-transmitted phytopathogenic bacteria that can alter plant morphology and the longevity and reproduction rates and behavior of their insect vectors. There are various examples of animal and plant parasites that alter the host phenotype to attract insect vectors, but it is unclear how these parasites accomplish this. We hypothesized that phytoplasmas produce effectors that modulate specific targets in their hosts leading to the changes in plant development and insect performance. Previously, we sequenced and mined the genome of Aster Yellows phytoplasma strain Witches’ Broom (AY-WB) and identified 56 candidate effectors. Here, we report that the secreted AY-WB protein 11 (SAP11) effector modulates plant defense responses to the advantage of the AY-WB insect vector Macrosteles quadrilineatus . SAP11 binds and destabilizes Arabidopsis CINCINNATA (CIN)-related TEOSINTE BRANCHED1, CYCLOIDEA, PROLIFERATING CELL FACTORS 1 and 2 (TCP) transcription factors, which control plant development and promote the expression of lipoxygenase ( LOX ) genes involved in jasmonate (JA) synthesis. Both the Arabidopsis SAP11 lines and AY-WB–infected plants produce less JA on wounding. Furthermore, the AY-WB insect vector produces more offspring on AY-WB–infected plants, SAP11 transgenic lines, and plants impaired in CIN-TCP and JA synthesis. Thus, SAP11-mediated destabilization of CIN-TCPs leads to the down-regulation of LOX2 expression and JA synthesis and an increase in M. quadrilineatus progeny. Phytoplasmas are obligate inhabitants of their plant host and insect vectors, in which the latter transmits AY-WB to a diverse range of plant species. This finding demonstrates that pathogen effectors can reach beyond the pathogen–host interface to modulate a third organism in the biological interaction.

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Pathogenic Mycoplasmas: Cultivation and Vertebrate Pathogenicity of a New Spiroplasma

1977-03-04

Joseph G. Tully , Robert F. Whitcomb , H. FRED CLARK +1 more

A spiroplasma recovered from allantoic fluids of chick embryos infected with the tick-derived suckling mouse cataract agent was grown in continuous passage on a new artificial culture medium. The cultured … A spiroplasma recovered from allantoic fluids of chick embryos infected with the tick-derived suckling mouse cataract agent was grown in continuous passage on a new artificial culture medium. The cultured organisms induced typical ocular and other disease symptoms in susceptible animals, and were reisolated from involved host tissues. Although spiroplasmas have been previously recognized as plant and insect pathogens, this is the first spiroplasma shown to multiply at 37 degrees C and to be pathogenic for vertebrates.

Revised Classification Scheme of Phytoplasmas based on RFLP Analyses of 16S rRNA and Ribosomal Protein Gene Sequences

1998-10-01

I.-M. LEE , Dawn E. Gundersen‐Rindal , Robert E. Davis +1 more

RFLP analyses of 16S rDNA nested PCR products from 34 phytoplasma strains with 17 restriction enzymes delineated distinct pattern types. Based on similarity coefficients derived from RFLP analyses, the 34 … RFLP analyses of 16S rDNA nested PCR products from 34 phytoplasma strains with 17 restriction enzymes delineated distinct pattern types. Based on similarity coefficients derived from RFLP analyses, the 34 representative phytoplasma strains were differentiated into 14 major groups (termed 16Sr groups) and 32 sub-groups. The similarity coefficients of RFLP patterns between distinct groups were 90% or below. By including additional groups and sub-groups from which RFLP analyses were not performed but for which 16S rDNA sequence data were available to predict restriction sites, a total of 14 groups and 41 sub-groups were proposed. By combined RFLP analyses of 16S rRNA and ribosomal protein gene sequences, thus far, a total of 46 subgroups have been recognized. The phytoplasma 16Sr groups were consistent with the phylogenetic groups (subclades) defined by phylogenetic analysis of near-full-length 16S rRNA gene sequences, indicating that the RFLP-based groups are phylogenetically valid. The approach using RFLP analyses of PCR-amplified 16S rDNA (and ribosomal protein gene sequences) provides a simple, reliable and rapid means for differentiation and classification of unknown phytoplasmas.

Quantitative real-time PCR for detection and identification of Candidatus Liberibacter species associated with citrus huanglongbing

2006-01-19

Wenbin Li , John S. Hartung , Laurène Lévy

Assessing genetic diversity and population structure in a citrus germplasm collection utilizing simple sequence repeat markers (SSRs)

2006-04-19

Noelle A. Barkley , Mikeal L. Roose , Robert Krueger +1 more

Asian citrus psyllid, <scp>D</scp>iaphorina citri, vector of citrus huanglongbing disease

2012-12-07

David G. Hall , Matthew L. Richardson , El‐Desouky Ammar +1 more

Abstract The Asian citrus psyllid ( ACP ), D iaphorina citri K uwayama ( H emiptera: P syllidae), is an important pest of citrus because it transmits phloem‐limited bacteria [ … Abstract The Asian citrus psyllid ( ACP ), D iaphorina citri K uwayama ( H emiptera: P syllidae), is an important pest of citrus because it transmits phloem‐limited bacteria [ C andidatus L iberibacter spp., notably C a . L . asiaticus ( LAS )] associated with huanglongbing ( HLB ; citrus greening disease), currently considered the world's most serious disease of citrus. Asian citrus psyllid transmits LAS in a persistent manner and, although the rate of LAS transmission by ACP individuals usually is low, HLB can spread rapidly in a citrus grove and the geographic range of the disease is expanding, threatening citrus industries in new areas. Intensive chemical control of ACP is the primary management strategy currently advocated for HLB , but this strategy is costly, unsustainable, and generally ineffective. The scientific community is searching aggressively for solutions to HLB on many fronts, but it could still be years before solutions are found and implemented. Plant resistance to LAS is one area of research being pursued, whereby traits that confer resistance are identified and incorporated into citrus germplasm through conventional or transgenic methods. It remains to be seen if a solution to HLB can be found that specifically targets ACP , but research on ACP has been stepped up in a number of areas, notably on ACP – LAS –plant interactions, on host plant resistance to ACP , and on molecular methods of silencing ACP genes to induce mortality or to block its ability to transmit HLB ‐causing bacteria. Advancements in these and other research areas may depend greatly on a better understanding of basic ACP biology and vector–pathogen–host plant interactions at the molecular, cellular, and community levels. Here, we present an updated review of ACP and HLB with an emphasis on the problem in Florida.

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Phytoplasma: Phytopathogenic Mollicutes

2000-10-01

Ing‐Ming Lee , Robert E. Davis , Dawn E. Gundersen‐Rindal

▪ Abstract During the past decade, research has yielded new knowledge about the plant and insect host ranges, geographical distribution, and phylogenetic relationships of phytoplasmas, and a taxonomic system has … ▪ Abstract During the past decade, research has yielded new knowledge about the plant and insect host ranges, geographical distribution, and phylogenetic relationships of phytoplasmas, and a taxonomic system has emerged in which distinct phytoplasmas are named as separate “Candidatus phytoplasma species.” In large part, this progress has resulted from the development and use of molecular methods to detect, identify, and classify phytoplasmas. While these advances continue, research has recently begun on the phytoplasma genome, how phytoplasmas cause disease, the role of mixed phytoplasmal infections in plant diseases, and molecular/genetic phenomena that underlie symptom development in plants. These and other recent advances are laying the foundation for future progress in understanding the mechanisms of phytoplasma pathogenicity, organization of the phytoplasma genome, evolution of new phytoplasma strains and emergence of new diseases, bases of insect transmissibility and specificity of transmission, and plant gene expression in response to phytoplasmal infection, as well as the design of novel approaches to achieve effective control of phytoplasmal diseases.

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Current Epidemiological Understanding of Citrus Huanglongbing

2010-07-01

T. R. Gottwald

Huanglongbing (HLB) is the most destructive citrus pathosystem worldwide. Previously known primarily from Asia and Africa, it was introduced into the Western Hemisphere in 2004. All infected commercial citrus industries … Huanglongbing (HLB) is the most destructive citrus pathosystem worldwide. Previously known primarily from Asia and Africa, it was introduced into the Western Hemisphere in 2004. All infected commercial citrus industries continue to decline owing to inadequate current control methods. HLB increase and regional spatial spread, related to vector populations, are rapid compared with other arboreal pathosystems. Disease dynamics result from multiple simultaneous spatial processes, suggesting that psyllid vector transmission is a continuum from local area to very long distance. Evolutionarily, HLB appears to have originated as an insect endosymbiont that has moved into plants. Lack of exposure of citrus to the pathogen prior to approximately 100 years ago did not provide sufficient time for development of resistance. A prolonged incubation period and regional dispersal make eradication nonviable. Multiple asymptomatic infections per symptomatic tree, incomplete systemic distribution within trees, and prolonged incubation period make detection difficult and greatly complicate disease control.

Comparison of two aerial imaging platforms for identification of Huanglongbing-infected citrus trees

2013-01-17

Francisco García-Ruiz , Sindhuja Sankaran , Joe Mari Maja +3 more

PCR detection of the two«Candidatus»liberobacter species associated with greening disease of citrus

1996-02-01

Sandrine Jagoueix , Joseph M. Bové , M. Garnier

INSECT VECTORS OF PHYTOPLASMAS

2005-09-22

Phyllis G. Weintraub , LeAnn Beanland

▪ Abstract Plant diseases caused by, or associated with, phytoplasmas occur in hundreds of commercial and native plants, causing minor to extensive damage. Insect vectors, primarily leafhoppers, planthoppers, and psyllids, … ▪ Abstract Plant diseases caused by, or associated with, phytoplasmas occur in hundreds of commercial and native plants, causing minor to extensive damage. Insect vectors, primarily leafhoppers, planthoppers, and psyllids, have been identified for relatively few phytoplasma diseases, limiting the capacity of managers to make informed decisions to protect crops and endangered indigenous plants. In the past two decades our knowledge of insect vector–phytoplasma interactions has increased dramatically, allowing researchers to make more accurate predictions about the nature and epidemiology of phytoplasma diseases. These better-characterized systems also may provide clues to the identity of insect vectors of other phytoplasma-associated diseases. We review the literature addressing the ecology of insect vectors, phytoplasma-insect ecological and molecular interactions, vector movement and dispersal, and possible management strategies with an emphasis on research from the past 20 years.

Complete Genome Sequence of Citrus Huanglongbing Bacterium, ‘CandidatusLiberibacter asiaticus’ Obtained Through Metagenomics

2009-07-09

Yongping Duan , Lijuan Zhou , David G. Hall +7 more

Citrus huanglongbing is the most destructive disease of citrus worldwide. It is spread by citrus psyllids and is associated with a low-titer, phloem-limited infection by any of three uncultured species … Citrus huanglongbing is the most destructive disease of citrus worldwide. It is spread by citrus psyllids and is associated with a low-titer, phloem-limited infection by any of three uncultured species of α-Proteobacteria, ‘Candidatus Liberibacter asiaticus’, ‘Ca. L. americanus’, and ‘Ca. L. africanus’. A complete circular ‘Ca. L. asiaticus’ genome has been obtained by metagenomics, using the DNA extracted from a single ‘Ca. L. asiaticus’–infected psyllid. The 1.23-Mb genome has an average 36.5% GC content. Annotation revealed a high percentage of genes involved in both cell motility (4.5%) and active transport in general (8.0%), which may contribute to its virulence. ‘Ca. L. asiaticus’ appears to have a limited ability for aerobic respiration and is likely auxotrophic for at least five amino acids. Consistent with its intracellular nature, ‘Ca. L. asiaticus’ lacks type III and type IV secretion systems as well as typical free-living or plant-colonizing extracellular degradative enzymes. ‘Ca. L. asiaticus’ appears to have all type I secretion system genes needed for both multidrug efflux and toxin effector secretion. Multi-protein phylogenetic analysis confirmed ‘Ca. L. asiaticus’ as an early-branching and highly divergent member of the family Rhizobiaceae. This is the first genome sequence of an uncultured α-proteobacteria that is both an intracellular plant pathogen and insect symbiont.

Ultrasensitive detection of phytoplasmas by nested-PCR assays using two universal primer pairs.

1996-12-04

D. E. Gundersen , I. M. Lee

‘Candidatus Phytoplasma asteris’, a novel phytoplasma taxon associated with aster yellows and related diseases

2004-07-01

I.-M. Lee , Dawn E. Gundersen‐Rindal , Robert E. Davis +3 more

Aster yellows (AY) group (16SrI) phytoplasmas are associated with over 100 economically important diseases worldwide and represent the most diverse and widespread phytoplasma group. Strains that belong to the AY … Aster yellows (AY) group (16SrI) phytoplasmas are associated with over 100 economically important diseases worldwide and represent the most diverse and widespread phytoplasma group. Strains that belong to the AY group form a phylogenetically discrete subclade within the phytoplasma clade and are related most closely to the stolbur phytoplasma subclade, based on analysis of 16S rRNA gene sequences. AY subclade strains are related more closely to their culturable relatives, Acholeplasma spp., than any other phytoplasmas known. Within the AY subclade, six distinct phylogenetic lineages were revealed. Congruent phylogenies obtained by analyses of tuf gene and ribosomal protein ( rp ) operon gene sequences further resolved the diversity among AY group phytoplasmas. Distinct phylogenetic lineages were identified by RFLP analysis of 16S rRNA, tuf or rp gene sequences. Ten subgroups were differentiated, based on analysis of rp gene sequences. It is proposed that AY group phytoplasmas represent at least one novel taxon. Strain OAY, which is a member of subgroups 16SrI-B, rp I-B and tuf I-B and is associated with evening primrose ( Oenothera hookeri ) virescence in Michigan, USA, was selected as the reference strain for the novel taxon ‘ Candidatus Phytoplasma asteris’. A comprehensive database of diverse AY phytoplasma strains and their geographical distribution is presented.

Association of Bactericera cockerelli (Homoptera: Psyllidae) with “Zebra Chip,” a New Potato Disease in Southwestern United States and Mexico

2007-06-01

Joseph E. Munyaneza , J. M. Crosslin , J. E. Upton

A new defect of potato, Solanum tuberosum L., "zebra chip," so named for the characteristic symptoms that develop in fried chips from infected potato tubers, has recently been documented in … A new defect of potato, Solanum tuberosum L., "zebra chip," so named for the characteristic symptoms that develop in fried chips from infected potato tubers, has recently been documented in several southwestern states of the United States, in Mexico, and in Central America. This defect is causing millions of dollars in losses to both potato producers and processors. Zebra chip plant symptoms resemble those caused by potato purple top and psyllid yellows diseases. Experiments were conducted to elucidate the association between the psyllid Bactericera cockerelli (Sulc) (Homoptera: Psyllidae) and zebra chip by exposing clean potato plants to this insect under greenhouse and field conditions. Potato plants and tubers exhibiting zebra chip symptoms were tested for phytoplasmas by polymerase chain reaction. Potato psyllids collected from infected potato fields also were tested. Results indicated that there was an association between the potato psyllid and zebra chip. Plants exposed to psyllids in the greenhouse and field developed zebra chip. In the greenhouse, 25.8 and 59.2% of tubers exhibited zebra chip symptoms in the raw tubers and fried chips, respectively. In the field, 15 and 57% of tubers showed symptoms in raw tubers and chips, respectively. No zebra chip was observed in tubers from plants that had not been exposed to psyllids, either in the greenhouse or field. No phytoplasmas were detected from potato plants or tubers with zebra chip symptoms, suggesting that these pathogens are not involved in zebra chip. Of the 47 samples of potato psyllids tested, only two tested positive for the Columbia Basin potato purple top phytoplasma.

T<scp>HE</scp>B<scp>IOLOGY OF</scp>X<scp>YLEM</scp>F<scp>LUID</scp>–F<scp>EEDING</scp>I<scp>NSECT</scp>V<scp>ECTORS OF</scp>X<scp>YLELLA FASTIDIOSA</scp><scp>AND</scp>T<scp>HEIR</scp>R<scp>ELATION TO</scp>D<scp>ISEASE</scp>E<scp>PIDEMIOLOGY</scp>

2004-01-01

Richard A. Redak , Alexander H. Purcell , João Roberto Spotti Lopes +3 more

▪ Abstract Xylophagous leafhopppers are common and abundant insects of tropical and subtropical environments and play important ecological roles in these ecosystems. The feeding biology of these insects is unique … ▪ Abstract Xylophagous leafhopppers are common and abundant insects of tropical and subtropical environments and play important ecological roles in these ecosystems. The feeding biology of these insects is unique in terms of their high feeding rates and a digestive physiology that allows them to assimilate amino acids, organic acids, and sugars at approximately 99% efficiency. For those species well studied, fluctuations in plant xylem chemistry and tension appear to determine the diurnal and seasonal use of their host plants. Relatively few species of xylem fluid–feeding leafhoppers are considered important pests in commercial agriculture, as they transmit the bacterial plant pathogen Xylella fastidiosa. X. fastidiosa induces diseases of grapevines, citrus, coffee, almond, alfalfa, stone fruits, landscape ornamentals, and native hardwoods for which there is no cure. Two Xylella diseases, citrus variegated chlorosis (CVC) and Pierce's disease (PD) of grapevines, have emerged as important issues within the past decade. In Brazil, CVC became important in the early 1990s and has now expanded throughout many citrus-growing areas of South America and threatens to spread to North America. The recent establishment of the exotic glassy-winged sharpshooter (Homalodisca coagulata) in California now threatens much of the United States' wine grape, table grape, and almond production. The spread of H. coagulata throughout southern California and the spread of CVC northward from Argentina through Brazil exemplifies the biological risks from exotic species. The occurrence and epidemiology of leafhopper-vectored Xylella diseases are discussed.

FASTIDIOUS XYLEM-LIMITED BACTERIAL PLANT PATHOGENS

1996-09-01

Alexander H. Purcell , D. L. Hopkins

Numerous bacteria have been isolated from within plants, and many reported from xylem, but only three species of xylem-limited bacteria (XLB) that are fastidious in cultural requirements, are plant pathogens, … Numerous bacteria have been isolated from within plants, and many reported from xylem, but only three species of xylem-limited bacteria (XLB) that are fastidious in cultural requirements, are plant pathogens, and exclusively occupy xylem, have been well characterized. Two XLB, Xylella fastidiosa and Pseudomonas syzygii, are transmitted by sucking insects that feed on xylem sap but are not transmitted mechanically from plant to plant. In contrast, Clavibacter xyli is mechanically transmitted to plants by cutting tools. All of these XLB occupy a highly specialized yet diverse ecological niche: the water-conducting systems of an extremely wide range of plant hosts. A variety of detection methods are available as diagnostic aids; each method has advantages and disadvantages; no single method is best for all uses. Molecular and genetic comparisons of strains of XLB lag behind progress being made for many other plant-pathogenic bacteria, but such studies are needed to answer important questions: (a) How do XLB move from cell to cell within plants? (b) What are the physiological and genetic bases of plant host specificity for XLB? (c) Why are only xylem-feeding specialists vectors of X. fastidiosa (and probably P. syzygii), when many leafhoppers feed regularly (but not continuously) on xylem?

Citrus Huanglongbing: The Pathogen and Its Impact

2007-01-01

T. R. Gottwald , John V. da Graça , Renato Beozzo Bassanezi

Citrus Huanglongbing, aka greening disease, has been the subject of several reviews in recent years. In this article, the author presents a concise compilation of the main features and symptoms … Citrus Huanglongbing, aka greening disease, has been the subject of several reviews in recent years. In this article, the author presents a concise compilation of the main features and symptoms of the disease, the causal organisms and the vectors including impacts for Florida and Brazil, two relatively new areas where the disease has been discovered, as well as implications for California, Texas, and Arizona citrus industries, which are threatened by the close proximity to the new Florida epidemic, and the rest of the western hemisphere. Accepted for publication 19 June 2007. Published 6 September 2007.

Phytoplasma-specific PCR primers based on sequences of the 16S-23S rRNA spacer region

1996-08-01

Christine D. Smart , Bernd Schneider , C. L. Blomquist +6 more

In order to develop a diagnostic tool to identify phytoplasmas and classify them according to their phylogenetic group, we took advantage of the sequence diversity of the 16S-23S intergenic spacer … In order to develop a diagnostic tool to identify phytoplasmas and classify them according to their phylogenetic group, we took advantage of the sequence diversity of the 16S-23S intergenic spacer regions (SRs) of phytoplasmas. Ten PCR primers were developed from the SR sequences and were shown to amplify in a group-specific fashion. For some groups of phytoplasmas, such as elm yellows, ash yellows, and pear decline, the SR primer was paired with a specific primer from within the 16S rRNA gene. Each of these primer pairs was specific for a specific phytoplasma group, and they did not produce PCR products of the correct size from any other phytoplasma group. One primer was designed to anneal within the conserved tRNA(Ile) and, when paired with a universal primer, amplified all phytoplasmas tested. None of the primers produced PCR amplification products of the correct size from healthy plant DNA. These primers can serve as effective tools for identifying particular phytoplasmas in field samples.

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Biology and Management of Asian Citrus Psyllid, Vector of the Huanglongbing Pathogens

2013-01-07

Elizabeth E. Grafton‐Cardwell , Lukasz L. Stelinski , Philip A. Stansly

The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), is the most important pest of citrus worldwide because it serves as a vector of “Candidatus Liberibacter” species (Alphaproteobacteria) that cause … The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), is the most important pest of citrus worldwide because it serves as a vector of “Candidatus Liberibacter” species (Alphaproteobacteria) that cause huanglongbing (citrus greening disease). All commercially cultivated citrus is susceptible and varieties tolerant to disease expression are not yet available. Onset of disease occurs following a long latent period after inoculation, and thus the pathogen can spread widely prior to detection. Detection of the pathogen in Brazil in 2004 and Florida in 2005 catalyzed a significant increase in research on D. citri biology. Chemical control is the primary management strategy currently employed, but recently documented decreases in susceptibility of D. citri to several insecticides illustrate the need for more sustainable tools. Herein, we discuss recent advances in the understanding of D. citri biology and behavior, pathogen transmission biology, biological control, and chemical control with respect to “Candidatus Liberibacter asiaticus.” Our goal is to point toward integrated and biologically relevant management of this pathosystem.

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‘Candidatus Phytoplasma’, a taxon for the wall-less, non-helical prokaryotes that colonize plant phloem and insects

2004-07-01

The trivial name 'phytoplasma' has been adopted to collectively name wall-less, non-helical prokaryotes that colonize plant phloem and insects, which were formerly known as mycoplasma-like organisms. Although phytoplasmas have not … The trivial name 'phytoplasma' has been adopted to collectively name wall-less, non-helical prokaryotes that colonize plant phloem and insects, which were formerly known as mycoplasma-like organisms. Although phytoplasmas have not yet been cultivated in vitro, phylogenetic analyses based on various conserved genes have shown that they represent a distinct, monophyletic clade within the class Mollicutes. It is proposed here to accommodate phytoplasmas within the novel genus 'Candidatus (Ca.) Phytoplasma'. Given the diversity within 'Ca. Phytoplasma', several subtaxa are needed to accommodate organisms that share <97.5% similarity among their 16S rRNA gene sequences. This report describes the properties of 'Ca. Phytoplasma', a taxon that includes the species 'Ca. Phytoplasma aurantifolia' (the prokaryote associated with witches'-broom disease of small-fruited acid lime), 'Ca. Phytoplasma australiense' (associated with Australian grapevine yellows), 'Ca. Phytoplasma fraxini' (associated with ash yellows), 'Ca. Phytoplasma japonicum' (associated with Japanese hydrangea phyllody), 'Ca. Phytoplasma brasiliense' (associated with hibiscus witches'-broom in Brazil), 'Ca. Phytoplasma castaneae' (associated with chestnut witches'-broom in Korea), 'Ca. Phytoplasma asteris' (associated with aster yellows), 'Ca. Phytoplasma mali' (associated with apple proliferation), 'Ca. Phytoplasma phoenicium' (associated with almond lethal disease), 'Ca. Phytoplasma trifolii' (associated with clover proliferation), 'Ca. Phytoplasma cynodontis' (associated with Bermuda grass white leaf), 'Ca. Phytoplasma ziziphi' (associated with jujube witches'-broom), 'Ca. Phytoplasma oryzae' (associated with rice yellow dwarf) and six species-level taxa for which the Candidatus species designation has not yet been formally proposed (for the phytoplasmas associated with X-disease of peach, grapevine flavescence dorée, Central American coconut lethal yellows, Tanzanian lethal decline of coconut, Nigerian lethal decline of coconut and loofah witches'-broom, respectively). Additional species are needed to accommodate organisms that, despite their 16S rRNA gene sequence being >97.5% similar to those of other 'Ca. Phytoplasma' species, are characterized by distinctive biological, phytopathological and genetic properties. These include 'Ca. Phytoplasma pyri' (associated with pear decline), 'Ca. Phytoplasma prunorum' (associated with European stone fruit yellows), 'Ca. Phytoplasma spartii' (associated with spartium witches'-broom), 'Ca. Phytoplasma rhamni' (associated with buckthorn witches'-broom), 'Ca. Phytoplasma allocasuarinae' (associated with allocasuarina yellows), 'Ca. Phytoplasma ulmi' (associated with elm yellows) and an additional taxon for the stolbur phytoplasma. Conversely, some organisms, despite their 16S rRNA gene sequence being <97.5% similar to that of any other 'Ca. Phytoplasma' species, are not presently described as Candidatus species, due to their poor overall characterization.

Living in two Worlds: The Plant and Insect Lifestyles ofXylella fastidiosa

2008-04-18

Subhadeep Chatterjee , Rodrigo P. P. Almeida , Steven E. Lindow

Diseases caused by Xylella fastidiosa have attained great importance worldwide as the pathogen and its insect vectors have been disseminated. Since this is the first plant pathogenic bacterium for which … Diseases caused by Xylella fastidiosa have attained great importance worldwide as the pathogen and its insect vectors have been disseminated. Since this is the first plant pathogenic bacterium for which a complete genome sequence was determined, much progress has been made in understanding the process by which it spreads within the xylem vessels of susceptible plants as well as the traits that contribute to its acquisition and transmission by sharpshooter vectors. Athough this pathogen shares many similarities with Xanthomonas species, such as its use of a small fatty acid signal molecule to coordinate virulence gene expression, the traits that it utilizes to cause disease and the manner in which they are regulated differ substantially from those of related plant pathogens. Its complex lifestyle as both a plant and insect colonist involves traits that are in conflict with these stages, thus apparently necessitating the use of a gene regulatory scheme that allows cells expressing different traits to co-occur in the plant.

Xylella fastidiosa: Cause of Pierce's Disease of Grapevine and Other Emergent Diseases

2002-10-01

D. L. Hopkins , Alexander H. Purcell

Construction of an interactive online phytoplasma classification tool, iPhyClassifier, and its application in analysis of the peach X-disease phytoplasma group (16SrIII)

2009-07-21

Yanan Zhao , Wei Wei , I.-M. Lee +3 more

Phytoplasmas, the causal agents of numerous plant diseases, are insect-vector-transmitted, cell-wall-less bacteria descended from ancestral low-G+C-content Gram-positive bacteria in the Bacillus–Clostridium group. Despite their monophyletic origin, widely divergent phytoplasma lineages … Phytoplasmas, the causal agents of numerous plant diseases, are insect-vector-transmitted, cell-wall-less bacteria descended from ancestral low-G+C-content Gram-positive bacteria in the Bacillus–Clostridium group. Despite their monophyletic origin, widely divergent phytoplasma lineages have evolved in adaptation to specific ecological niches. Classification and taxonomic assignment of phytoplasmas have been based primarily on molecular analysis of 16S rRNA gene sequences because of the inaccessibility of measurable phenotypic characters suitable for conventional microbial characterization. In the present study, an interactive online tool, iPhyClassifier, was developed to expand the efficacy and capacity of the current 16S rRNA gene sequence-based phytoplasma classification system. iPhyClassifier performs sequence similarity analysis, simulates laboratory restriction enzyme digestions and subsequent gel electrophoresis and generates virtual restriction fragment length polymorphism (RFLP) profiles. Based on calculated RFLP pattern similarity coefficients and overall sequence similarity scores, iPhyClassifier makes instant suggestions on tentative phytoplasma 16Sr group/subgroup classification status and 'Candidatus Phytoplasma' species assignment. Using iPhyClassifier, we revised and updated the classification of strains affiliated with the peach X-disease phytoplasma group. The online tool can be accessed at http://www.ba.ars.usda.gov/data/mppl/iPhyClassifier.html.

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Insecticide resistance in field populations of Asian citrus psyllid in Florida

2011-05-02

Siddharth Tiwari , Rajinder S. Mann , Michael E. Rogers +1 more

Abstract BACKGROUND: Asian citrus psyllid (ACP), Diaphorina citri , is a major pest of citrus because it vectors the putative causal agent of huanglongbing disease. Insecticides are currently the basis … Abstract BACKGROUND: Asian citrus psyllid (ACP), Diaphorina citri , is a major pest of citrus because it vectors the putative causal agent of huanglongbing disease. Insecticides are currently the basis of psyllid management programs, and the number of annual insecticide applications has increased significantly. In this paper, a series of investigations of insecticide resistance among field populations of adult and immature ACP in Florida is described. RESULTS: In 2009, the highest level of resistance for adult ACP, as compared with the laboratory susceptible (LS) population, was found with imidacloprid with an LD 50 resistance ratio (RR 50 ) of 35 in one population. This was followed by chlorpyriphos (RR 50 = 17.9, 13.3, 11.8 and 6.9), thiamethoxam (RR 50 = 15 and 13), malathion (RR 50 = 5.4 and 5.0) and fenpropathrin (RR 50 = 4.8). In 2010, mortality of adults from all five sites sampled was lower than with the LS population at three diagnostic concentrations of each insecticide tested. Among nymph populations, indications of resistance were observed with carbaryl (RR 50 = 2.9), chlorpyriphos (RR 50 = 3.2), imidacloprid (RR 50 = 2.3 and 3.9) and spinetoram (RR 50 = 4.8 and 5.9). General esterase, glutathione S‐transferase and monooxygenase levels were also elevated in field‐collected adult and nymph ACP as compared with the LS population. CONCLUSION: The present results suggest that varying levels of insecticide susceptibility exist in ACP populations across the citrus‐growing areas of Florida. Increased levels of detoxifying enzymes in these populations may partially explain these differences. The present results indicate that insecticide resistance may become an emerging problem for ACP control if effective resistance management is not practiced. Copyright © 2011 Society of Chemical Industry

The Phloem-Limited Bacterium of Greening Disease of Citrus Is a Member of the Subdivision of the Proteobacteria

1994-07-01

Sandrine Jagoueix , Joseph M. Bové , M. Garnier

Using the PCR, we amplified the 16S ribosomal DNAs (rDNAs) of an Asian strain and an African strain of the uncultured, gram-negative, walled, phloem-limited bacterium-like organism (BLO) associated with citrus … Using the PCR, we amplified the 16S ribosomal DNAs (rDNAs) of an Asian strain and an African strain of the uncultured, gram-negative, walled, phloem-limited bacterium-like organism (BLO) associated with citrus greening disease. We evaded coamplification of chloroplast 16S rDNA by using restriction enzymes; the chloroplast 16S rDNA was sensitive to BclI digestion and resistant to EcoRI digestion, while the 16S rDNA of the BLO was resistant to BclI digestion and sensitive to EcoRI digestion. The 16S rDNA of the African BLO strain was amplified from BclI-digested DNA extracted from infected periwinkle leaf midribs. The Asian strain was isolated from plant extract by using a specific monoclonal antibody coated onto the surface of a PCR tube. The 16S rDNAs of the two BLO strains were cloned and sequenced. Comparisons with sequences of 16S rDNAs obtained from the GenBank data base revealed that the two citrus greening disease BLOs belong to the alpha subdivision of the class Proteobacteria. Even though their closest relatives are members of the alpha-2 subgroup, these BLOs are distinct from this subgroup as we observed only 87.5% homology between the 16S rDNAs examined. Therefore, the two BLOs which we studied probably are members of a new lineage in the α subdivision of the Proteobacteria. We propose the trivial name "liberobacter" for this new group of bacteria and will wait until additional characteristics have been determined before we propose a formal name.

Phytoplasmas: bacteria that manipulate plants and insects

2008-04-30

Saskia A. Hogenhout , Kenro Oshima , El‐Desouky Ammar +3 more

Superkingdom Prokaryota; Kingdom Monera; Domain Bacteria; Phylum Firmicutes (low-G+C, Gram-positive eubacteria); Class Mollicutes; Candidatus (Ca.) genus Phytoplasma.Ca. Phytoplasma comprises approximately 30 distinct clades based on 16S rRNA gene sequence analyses … Superkingdom Prokaryota; Kingdom Monera; Domain Bacteria; Phylum Firmicutes (low-G+C, Gram-positive eubacteria); Class Mollicutes; Candidatus (Ca.) genus Phytoplasma.Ca. Phytoplasma comprises approximately 30 distinct clades based on 16S rRNA gene sequence analyses of approximately 200 phytoplasmas. Phytoplasmas are mostly dependent on insect transmission for their spread and survival. The phytoplasma life cycle involves replication in insects and plants. They infect the insect but are phloem-limited in plants. Members of Ca. Phytoplasma asteris (16SrI group phytoplasmas) are found in 80 monocot and dicot plant species in most parts of the world. Experimentally, they can be transmitted by approximately 30, frequently polyphagous insect species, to 200 diverse plant species.In plants, phytoplasmas induce symptoms that suggest interference with plant development. Typical symptoms include: witches' broom (clustering of branches) of developing tissues; phyllody (retrograde metamorphosis of the floral organs to the condition of leaves); virescence (green coloration of non-green flower parts); bolting (growth of elongated stalks); formation of bunchy fibrous secondary roots; reddening of leaves and stems; generalized yellowing, decline and stunting of plants; and phloem necrosis. Phytoplasmas can be pathogenic to some insect hosts, but generally do not negatively affect the fitness of their major insect vector(s). In fact, phytoplasmas can increase fecundity and survival of insect vectors, and may influence flight behaviour and plant host preference of their insect hosts.The most common practices are the spraying of various insecticides to control insect vectors, and removal of symptomatic plants. Phytoplasma-resistant cultivars are not available for the vast majority of affected crops.

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Computer-simulated RFLP analysis of 16S rRNA genes: identification of ten new phytoplasma groups

2007-08-01

Wei Wei , Robert E. Davis , Ing‐Ming Lee +1 more

Phytoplasmas are cell wall-less bacteria that cause numerous plant diseases. As no phytoplasma has been cultured in cell-free medium, phytoplasmas cannot be differentiated and classified by the traditional methods which … Phytoplasmas are cell wall-less bacteria that cause numerous plant diseases. As no phytoplasma has been cultured in cell-free medium, phytoplasmas cannot be differentiated and classified by the traditional methods which are applied to culturable prokaryotes. Over the past decade, the establishment of a phytoplasma classification scheme based on 16S rRNA restriction fragment length polymorphism (RFLP) patterns has enabled the accurate and reliable identification and classification of a wide range of phytoplasmas. In the present study, we expanded this classification scheme through the use of computer-simulated RFLP analysis, achieving rapid differentiation and classification of phytoplasmas. Over 800 publicly available phytoplasma 16S rRNA gene sequences were aligned using the CLUSTAL_X program and the aligned 1.25 kb fragments were exported to pDRAW32 software for in silico restriction digestion and virtual gel plotting. Based on distinctive virtual RFLP patterns and calculated similarity coefficients, phytoplasma strains were classified into 28 groups. The results included the classification of hundreds of previously unclassified phytoplasmas and the delineation of 10 new phytoplasma groups representing three recently described and seven novel putative 'Candidatus Phytoplasma' taxa.

Diversity of Endophytic Bacterial Populations and Their Interaction with Xylella fastidiosa in Citrus Plants

2002-09-25

Welington Luiz Araújo , Joelma Marcon , Walter Maccheroni +3 more

Citrus variegated chlorosis (CVC) is caused by Xylella fastidiosa, a phytopathogenic bacterium that can infect all Citrus sinensis cultivars. The endophytic bacterial communities of healthy, resistant, and CVC-affected citrus plants … Citrus variegated chlorosis (CVC) is caused by Xylella fastidiosa, a phytopathogenic bacterium that can infect all Citrus sinensis cultivars. The endophytic bacterial communities of healthy, resistant, and CVC-affected citrus plants were studied by using cultivation as well as cultivation-independent techniques. The endophytic communities were assessed in surface-disinfected citrus branches by plating and denaturing gradient gel electrophoresis (DGGE). Dominant isolates were characterized by fatty-acid methyl ester analysis as Bacillus pumilus, Curtobacterium flaccumfaciens, Enterobacter cloacae, Methylobacterium spp. (including Methylobacterium extorquens, M. fujisawaense, M. mesophilicum, M. radiotolerans, and M. zatmanii), Nocardia sp., Pantoea agglomerans, and Xanthomonas campestris. We observed a relationship between CVC symptoms and the frequency of isolation of species of Methylobacterium, the genus that we most frequently isolated from symptomatic plants. In contrast, we isolated C. flaccumfaciens significantly more frequently from asymptomatic plants than from those with symptoms of CVC while P. agglomerans was frequently isolated from tangerine (Citrus reticulata) and sweet-orange (C. sinensis) plants, irrespective of whether the plants were symptomatic or asymptomatic or showed symptoms of CVC. DGGE analysis of 16S rRNA gene fragments amplified from total plant DNA resulted in several bands that matched those from the bacterial isolates, indicating that DGGE profiles can be used to detect some endophytic bacteria of citrus plants. However, some bands had no match with any isolate, suggesting the occurrence of other, nonculturable or as yet uncultured, endophytic bacteria. A specific band with a high G+C ratio was observed only in asymptomatic plants. The higher frequency of C. flaccumfaciens in asymptomatic plants suggests a role for this organism in the resistance of plants to CVC.

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A New Huanglongbing Species, “ Candidatus Liberibacter psyllaurous,” Found To Infect Tomato and Potato, Is Vectored by the Psyllid Bactericera cockerelli (Sulc)

2008-08-02

Allison K. Hansen , John T. Trumble , Richard Stouthamer +1 more

A new huanglongbing (HLB) "Candidatus Liberibacter" species is genetically characterized, and the bacterium is designated "Candidatus Liberibacter psyllaurous." This bacterium infects the psyllid Bactericera cockerelli and its solanaceous host plants … A new huanglongbing (HLB) "Candidatus Liberibacter" species is genetically characterized, and the bacterium is designated "Candidatus Liberibacter psyllaurous." This bacterium infects the psyllid Bactericera cockerelli and its solanaceous host plants potato and tomato, potentially resulting in "psyllid yellowing." Host plant-dependent HLB transmission and variation in psyllid infection frequencies are found.

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KEYS TO THE FAMILIES OF CICADOMORPHA AND SUBFAMILIES AND TRIBES OF CICADELLIDAE (HEMIPTERA: AUCHENORRHYNCHA)

2005-12-01

Chris H. Dietrich

Illustrated keys to adults reflecting the current higher classification are provided for families of Cicadomorpha (cicadas, spittlebugs, leafhoppers, and treehoppers) and for subfamilies and tribes of Cicadellidae (leafhoppers), excluding Deltocephalinae. … Illustrated keys to adults reflecting the current higher classification are provided for families of Cicadomorpha (cicadas, spittlebugs, leafhoppers, and treehoppers) and for subfamilies and tribes of Cicadellidae (leafhoppers), excluding Deltocephalinae. The following families (and superfamilies) are recognized: Cicadidae and Tettigarctidae (Cicadoidea); Aphrophoridae, Cercopidae, Clastopteridae, Epipygidae, and Machaerotidae (Cercopoidea); Aetalionidae, Cicadellidae, Melizoderidae, Membracidae, Myerslopiidae (Membracoidea). The higher classification of Cicadellidae is currently undergoing revision, but a provisional key to subfamilies and tribes (except Deltocephalinae) is provided. Two new synonymies are proposed: Signoretiinae Baker, 1915 equals Phlogisinae Linnavuori, 1979, new synonym; Iassini Walker, 1870, equals Hyalojassini Evans, 1972, new synonym.

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Xylella Fastidiosa: Xylem-Limited Bacterial Pathogen of Plants

1989-09-01

D. L. Hopkins

Strains of Xylella fastidiosa have been associated with diseases that cause tremendous losses in many economically important plants, including grapevine, alfalfa, peach, plum, almond, elm, sycamore, oak, maple, and possibly … Strains of Xylella fastidiosa have been associated with diseases that cause tremendous losses in many economically important plants, including grapevine, alfalfa, peach, plum, almond, elm, sycamore, oak, maple, and possibly citrus (24, 28, 32, 35, 42, 43, 49, 57, 70, 72, 73, 78). This Gram-negative, xylem-limited bacterium (XLB) was first discovered associ ated with Pierce's disease (PD) of grapevine in 1973 (28, 42) and was first grown in axenic culture in 1978 (12). While there has been considerable progress in the study of this bacterium over the past 15 years, our knowledge of X. fastidiosa is still very limited. Much of the research to date has been of the descriptive type, involving symptom description and fulfillment of Koch's postulates. However, a few excellent fundamental studies have been done with X. faslidiosa and the diseases that it causes. Since it was the first to be cultured, more research has been done with the PD of grapevine strain of X. fastidiosa than with other strains. Pierce's disease may also be the most economically significant, especially in the southeastern USA where it is endemic and is the principal factor preventing the development of a grape industry based on the high-quality Vilis vinifera and V. labrusca grapes (33). Phony peach disease in the southeastern USA and plum leaf scald in Japanese plum on the delta of the Parana River, Argentina, are also responsible for severe losses (46, 49). X.fastidiosa causes serious leaf scorch and tree decline diseases in many different urban trees (32, 50, 51). X. fastidiosa may also be involved in some of the current forest decline problems that are of unkown etiology. These diseases in urban shade

ASIAN CITRUS PSYLLIDS (STERNORRHYNCHA: PSYLLIDAE) AND GREENING DISEASE OF CITRUS: A LITERATURE REVIEW AND ASSESSMENT OF RISK IN FLORIDA

2004-09-01

Susan E. Halbert , K. L. Manjunath

The Asian citrus psyllid, Diaphorina citri Kuwayama, was discovered in Florida in 1998. It can be one of the most serious pests of citrus if the pathogens that cause citrus … The Asian citrus psyllid, Diaphorina citri Kuwayama, was discovered in Florida in 1998. It can be one of the most serious pests of citrus if the pathogens that cause citrus greening disease (huanglongbing) are present. Citrus greening recently has been reported in Brazil by Fundecitrus, Brazil. The establishment of D. citri in Florida increases the possibility that the disease may become established. Diaphorina citri can be separated from about 13 other species of psyllids reported on citrus. The biology of D. citri makes it ideally suited to the Florida climate. Only two species, D. citri and Trioza erytreae (del Guercio), have been implicated in spread of citrus greening, a disease caused by highly fastidious phloem-inhabiting bacteria. The disease is characterized by blotchy mottle on the leaves, and misshapen, poorly colored off-tasting fruit. In areas where the disease is endemic, citrus trees may live for only 5-8 years and never bear usable fruit. The disease occurs throughout much of Asia and Africa south of the Sahara Desert, on several small islands in the Indian Ocean, and in the Saudi Arabian Peninsula. Transmission of citrus greening occurs primarily via infective citrus psyllids and grafting. It is transmissible experimentally through dodder and might be transmitted by seed from infected plants and transovarially in psyllid vectors. Citrus greening disease is restricted to Citrus and close citrus relatives because of the narrow host range of the psyllid vectors. Management of citrus greening disease is difficult and requires an integrated approach including use of clean stock, elimination of inoculum via voluntary and regulatory means, use of pesticides to control psyllid vectors in the citrus crop, and biological control of psyllid vectors in non-crop reservoirs. There is no place in the world where citrus greening disease occurs that it is under completely successful management. Eradication of citrus greening disease may be possible if it is detected early. Research is needed on rapid and robust diagnosis, disease epidemiology, and psyllid vector control.

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THE STRUCTURE OF A CHYMOTRYPTIC PEPTIDE FROM PSEUDOMONAS CYTOCHROME C-551

1963-11-01

WR GRAY , BS HARTLEY

Research Article| November 01 1963 THE STRUCTURE OF A CHYMOTRYPTIC PEPTIDE FROM PSEUDOMONAS CYTOCHROME C-551 WR GRAY; WR GRAY Search for other works by this author on: This Site PubMed … Research Article| November 01 1963 THE STRUCTURE OF A CHYMOTRYPTIC PEPTIDE FROM PSEUDOMONAS CYTOCHROME C-551 WR GRAY; WR GRAY Search for other works by this author on: This Site PubMed Google Scholar BS HARTLEY BS HARTLEY Search for other works by this author on: This Site PubMed Google Scholar Biochem J (1963) 89 (2): 379–380. https://doi.org/10.1042/bj0890379 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn Email Cite Icon Cite Get Permissions Citation WR GRAY, BS HARTLEY; THE STRUCTURE OF A CHYMOTRYPTIC PEPTIDE FROM PSEUDOMONAS CYTOCHROME C-551. Biochem J 1 November 1963; 89 (2): 379–380. doi: https://doi.org/10.1042/bj0890379 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsBiochemical Journal Search Advanced Search © 1963 The Biochemical Society1963 Article PDF first page preview Close Modal You do not currently have access to this content.

A checklist of the current valid species of the subfamily Triatominae Jeannel, 1919 (Hemiptera, Reduviidae) and their geographical distribution, with nomenclatural and taxonomic notes

2003-05-30

Cléber Galvão , R. U. Carcavallo , Dayse da Silva Rocha +1 more

A checklist of the 137 current valid species placed in the subfamily Triatominae and their geographical distribution is presented. Confirmed and doubtful synonyms are given, as are nomenclatural and taxonomic … A checklist of the 137 current valid species placed in the subfamily Triatominae and their geographical distribution is presented. Confirmed and doubtful synonyms are given, as are nomenclatural and taxonomic comments.

CARBAMYL PHOSPHATE, THE CARBAMYL DONOR IN ENZYMATIC CITRULLINE SYNTHESIS1

1955-02-01

Mary Jones , Leonard B. Spector , Fritz Lipmann

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCARBAMYL PHOSPHATE, THE CARBAMYL DONOR IN ENZYMATIC CITRULLINE SYNTHESIS1M. E. Jones, L. Spector, and F. LipmannCite this: J. Am. Chem. Soc. 1955, 77, 3, 819–820Publication Date (Print):February … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCARBAMYL PHOSPHATE, THE CARBAMYL DONOR IN ENZYMATIC CITRULLINE SYNTHESIS1M. E. Jones, L. Spector, and F. LipmannCite this: J. Am. Chem. Soc. 1955, 77, 3, 819–820Publication Date (Print):February 1, 1955Publication History Published online1 May 2002Published inissue 1 February 1955https://pubs.acs.org/doi/10.1021/ja01608a101https://doi.org/10.1021/ja01608a101research-articleACS PublicationsRequest reuse permissionsArticle Views208Altmetric-Citations307LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Genomics of the origin and evolution of Citrus

2018-02-01

Guohong Albert Wu , Javier Terol , Victoria Ibáñez +7 more

The genus Citrus, comprising some of the most widely cultivated fruit crops worldwide, includes an uncertain number of species. Here we describe ten natural citrus species, using genomic, phylogenetic and … The genus Citrus, comprising some of the most widely cultivated fruit crops worldwide, includes an uncertain number of species. Here we describe ten natural citrus species, using genomic, phylogenetic and biogeographic analyses of 60 accessions representing diverse citrus germ plasms, and propose that citrus diversified during the late Miocene epoch through a rapid southeast Asian radiation that correlates with a marked weakening of the monsoons. A second radiation enabled by migration across the Wallace line gave rise to the Australian limes in the early Pliocene epoch. Further identification and analyses of hybrids and admixed genomes provides insights into the genealogy of major commercial cultivars of citrus. Among mandarins and sweet orange, we find an extensive network of relatedness that illuminates the domestication of these groups. Widespread pummelo admixture among these mandarins and its correlation with fruit size and acidity suggests a plausible role of pummelo introgression in the selection of palatable mandarins. This work provides a new evolutionary framework for the genus Citrus. The origin, evolution and domestication of Citrus and the genealogy of the most important wild and cultivated citrus varieties. Citrus fruits are one of the most cultivated crops worldwide, yet the evolutionary relationships among citrus species remain uncertain. Daniel Rokhsar, Manuel Talon and colleagues analyse the genomes of 60 accessions that represent a diverse range of citrus species, including 30 newly sequenced citrus genomes. They characterize the diversity and evolution of citrus at the species level and identify interspecific citrus hybrids and admixtures—genetic mixing between previously isolated populations—that could be the result of human activities such as migration and agriculture. The authors identify 10 progenitor species and suggest that citrus originated in southeast Asia, diversifying during the late Miocene epoch through a rapid southeast Asian radiation that correlated with a changing climate, including the weakening of the monsoons. They also find extensive relatedness among mandarins and sweet oranges, showing a complex history of admixture during the domestication of these groups.

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The Effect of Candidatus Liberibacter solanacearum Infection on Phytohormones in Carrots and Their Role in Disease Symptoms

2025-06-25

Nofar Assoline , Orit Dror , Atalya Keshet-Sitton +4 more | Phytopathology

Candidatus Liberibacter solanacearum (Lso), haplotype D, is an insect-transmitted, phloem-limited bacterium that induces developmental abnormalities in carrots, including witches’ broom and hairy root symptoms. We hypothesize that these symptoms result … Candidatus Liberibacter solanacearum (Lso), haplotype D, is an insect-transmitted, phloem-limited bacterium that induces developmental abnormalities in carrots, including witches’ broom and hairy root symptoms. We hypothesize that these symptoms result from Lso-induced hormonal imbalances. To investigate this, we analyzed the spatial and temporal distribution of Lso in carrot plants and assessed its effects on hormone-related gene expression and phytohormone levels. Our findings revealed that Lso first accumulates in the shoot apical meristem before spreading to root tissues, aligning with phloem flow dynamics. Transcriptomic and biochemical analyses indicated that cytokinin (CK) biosynthesis and response genes were upregulated, while gibberellin biosynthesis genes were downregulated. In contrast, no significant changes were observed in auxin biosynthesis or signaling. Hormone quantification further demonstrated increased CK levels in lateral roots and decreased CK levels in the root meristem of infected plants, with no detectable changes in auxin levels. Additionally, salicylic acid (SA) and jasmonic acid (JA) were significantly elevated following Lso infection, suggesting a persistent plant defense response. To validate the role of CK and auxin in symptom development, we applied synthetic growth regulators to infected and uninfected plants. CK treatment exacerbated witches’ broom symptoms, while auxin application mitigated this phenotype but enhanced lateral root formation. These results suggest that Lso manipulates phytohormone homeostasis to induce disease symptoms, offering a potential avenue for symptom mitigation through targeted hormone applications. Our findings provide novel insights into the role of plant hormones in Lso pathogenesis and highlight new strategies for managing carrot yellows disease.

High-Sensitivity RT-LAMP Assay Enables Rapid, Field-Deployable Detection of Candidatus Liberibacter Asiaticus in Crude DNA Extracts from Citrus Phyllosphere and Psyllid Vectors

2025-06-24

Ummad ud din Umar , Syed Muhammad Zaka , Muhammad Tahir +4 more | Deleted Journal

Lantana camara L.: a potential biocontrol agent against phytoplasma infection in chili plants

2025-06-24

Smriti Mall , Apoorva Srivastava , Gargee Singh | International Journal of Phytoremediation

Phytoplasma, a phytopathogenic mollicute, poses a major threat to global agriculture with no effective control strategies currently available. Lantana camara L., an invasive weed, contains bioactive compounds with promising antimicrobial … Phytoplasma, a phytopathogenic mollicute, poses a major threat to global agriculture with no effective control strategies currently available. Lantana camara L., an invasive weed, contains bioactive compounds with promising antimicrobial potential. This study investigates its potential, by utilizing the bioactive potential of green unripe berry extract from Lantana camara L., to mitigate phytoplasma infections in chili plants (Capsicum annuum). Phytoplasma infection in symptomatic chili plants was confirmed by nested PCR. Treatment with optimized L. camara extract led to significant recovery from little leaf disease. GC-MS analysis of Lantana camara L. green unripe berries identified six bioactive compounds with potential phytoplasma-inhibitory and antibacterial properties. To further explore their therapeutic potential, molecular docking studies were performed against the target protein SAP05 effector complexed with AtRpn10 (PDB ID: 8JTL) which is a known effector protein associated with phytoplasma pathogenicity. Among the docked compounds, Carsalam showed the strongest binding affinity (-7.2 kcal/mol) by interacting with Lys56 (C) residue. Other compounds like 5-(4-Chlorobenzyl)-1H-tetrazole and Cyclohexylmethylphosphonic acid also exhibited strong binding and targeted critical residues involved in protein function. These findings suggest L. camara has the potential to inhibit phytoplasma, marking a preliminary step toward sustainable phytoplasma management and an alternative to chemical treatments.

First report of Xylella fastidiosa subsp. multiplex associated with bacterial leaf scorch on American elderberry (Sambucus canadensis L.) in Oklahoma

2025-06-23

Mustafa Ojonuba Jibrin , Jennifer Olson , Yasmin Cavalcante de Andrade +1 more | Plant Disease

American black elderberry, Sambucus canadensis L., is a woody deciduous shrub rich in antioxidants belonging to the Adoxaceae and is native to North America (Lee and Finn, 2007; Osman et … American black elderberry, Sambucus canadensis L., is a woody deciduous shrub rich in antioxidants belonging to the Adoxaceae and is native to North America (Lee and Finn, 2007; Osman et al. 2023). S. canadensis L. is considered a homotypic synonym of Sambucus nigra subsp. canadensis (L.) Bolli), the European elderberry (Bolli, 1994). In Oklahoma, elderberries are usually harvested from wild growing plants, but recent efforts have seen an upsurge in acreage in elderberry production (Carroll, 2017). In 2024, mild to severe leaf scorch symptoms were observed on all the elderberry plants (about 5 plants within 1-3 meters of each other) in the Oklahoma State University Native Plant Corridor collections in Stillwater campus. Leaf scorch symptoms were characterized by tan to brown, irregularly shaped necrotic lesions along the leaf margins which eventually spread to the entire leaflet resulting in curling of the leaflet and defoliation . Symptomatic leaves were collected from all the five elderberry plants for pathogen identification. Samples were processed within three days. The petiole and midrib of ten elderberry leaves showing symptoms were freeze-dried for 24 hours. Thereafter, samples were ground to powder in a Genogrinder for 3 minutes. DNA was extracted from ground petiole and midrib using NucleoSpin Plant II kit (Machereey-Nagel, Duren, Germany) following the manufacturer's protocol. The ten DNA samples were tested for the presence/ absence of Xylella fastidiosa (Xf) using Q-PCR, with positive control (DNA of Xf subsp. multiplex (Xfm) strain M12 and Xf subsp. fastidiosa (Xff) strain M23 and negative control (water). SYBR-green real-time PCR with primer sets Teme150fc/Teme454rg (more specific to Xff) and Dixon454fa/Dixon1261rg (more specific to Xfm) (Chen et al., 2005), yielding Ct values ranging from 23.71-30.55 and 14.63-28.6 for both primer sets respectively, as contrasting to no Ct in control, suggesting Xfm infection (lower Ct values). For a whole genome level evaluation, next generation sequencing was carried out on one sample, STW-2 (Ct = 14.63 for Dixon454fa/Dixon1261rg), using the Illumina NovaSeqX Plus platform as described previously (Bock et al. 2025). A total of 180 M paired reads (150 bp each) was generated with a mapping rate of 11.09% to Xfm M12 (NC_010513.1) and 10.72% to Xff M23 (NC_010577.1) using Bowtie2 (Langmead and Salzberg, 2012), suggesting the Xfm identity. A BLAST search using the top 5 and bottom 5 reads in the mapped read data against the NCBI (National Center for Biotechnology Information) core-nr database showed that all the top hits were Xfm (query coverage = 100%, Percentage Identity = 100%). The assembled draft genome of STW-2 (GenBank accession number JBNVQL000000000) has an average nucleotide index (ANI) of 99.7 to M12 and 98.0 to M23. All three analyses (PCR, whole genome read-mapping, and NCBI BLAST search) confirmed the association of Xfm to STW-2. Xff was previously isolated from an elderberry plant growing in a grape vineyard in Florida and was reported to cause mild symptoms on grapevines (Hopkins, 2005). This is the first report of Xfm associated with bacterial leaf scorch on elderberry. This finding is therefore important in understanding epidemiology and management of Xfm in the increasingly important elderberry production landscape and potential spread to other horticultural plants in Oklahoma.

Amphicercidus (Hemiptera, Aphidinae, Macrosiphini) species in China: two synonyms and two new records

2025-06-23

Ying Xu , Jing Chen , Bakhtiyor Kholmatov +2 more | ZooKeys

Amphicercidus Oestlund, 1923 is distinguished from other aphid genera by a body in life heavily covered with white wax powder, antennal segment III rather long and with numerous secondary rhinaria, … Amphicercidus Oestlund, 1923 is distinguished from other aphid genera by a body in life heavily covered with white wax powder, antennal segment III rather long and with numerous secondary rhinaria, body dorsal setae long and pointed, the second hind tarsal segment longer than the ultimate rostral segment, siphunculi as long stout cylinders, and cauda broad and short. Based on the examination of Chinese specimens, two species were found to be synonyms of Amphicercidus japonicus (Hori, 1927): Amphicercidus forsythiae Zhang, Zhong & Zhang, 1992, syn. nov. and Amphicercidus sinilonicericola Zhang, 1980, syn. nov. Additionally, Amphicercidus pulverulens (Gillette, 1911) and Amphicercidus tuberculatus David, Narayanan & Rajasingh, 1971 are reported here as new records for China. Additionally, Lonicera (Caprifoliaceae) is a new host plant record for Amphicercidus pulverulens . The DNA barcodes for A. japonicus , A. pulverulens and A. tuberculatus have been obtained, with the barcodes of A. pulverulens and A. tuberculatus being acquired for the first time. Keys to Chinese species in this genus are presented.

Missing data and model selection in phylogenomics: A re‐evaluation of Cicadomorpha (Hemiptera: Auchenorrhyncha) superfamily level relationships

2025-06-22

Bin Yan , Chris H. Dietrich , Xiaofei Yu +6 more | Journal of Systematics and Evolution

Abstract Cicadomorpha, the most diverse infraorder of hemipteran insects, is a group of plant sap‐sucking insects consisting of three monophyletic superfamilies: Cercopoidea, Cicadoidea, and Membracoidea. This study aims to resolve … Abstract Cicadomorpha, the most diverse infraorder of hemipteran insects, is a group of plant sap‐sucking insects consisting of three monophyletic superfamilies: Cercopoidea, Cicadoidea, and Membracoidea. This study aims to resolve the controversy surrounding the phylogenetic relationships between these superfamilies, specifically whether Cercopoidea is more closely related to Cicadoidea (topology H1) or Membracoidea (topology H2). To tackle this issue, we assembled four matrices, including three amino acid datasets and one nucleotide dataset, and performed comprehensive phylogenomic analyses using both coalescent and concatenation methods. Our results showed that the amino acid matrix with low ratio of missing data‐based analyses strongly supported topology H2, indicating that Cercopoidea is sister to Membracoidea. However, the other three matrices yielded conflicting results. Interestingly, when site‐heterogeneous models were used, the results flipped, and the datasets that previously supported topology H1 supported topology H2. Further analyses, including model comparisons, tree topology tests, and phylogenetic analyses without an outgroup, also supported the conclusion that Cercopoidea is more closely related to Membracoidea. The study highlights the importance of modeling among site compositional heterogeneity in phylogenomic analyses to mitigate systematic errors. Additionally, we noted that datasets with high missing data ratios may lead to conflicting phylogenetic relationships. Our study provides strong evidence that Cercopoidea is sister to Membracoidea and highlights the importance of careful methodological considerations in phylogenetic analyses.

A Case Study for Visual Detection of a Systemic Disease: Optimizing Identification of Phony Peach Disease Based on Statistical and Machine Learning Models

2025-06-22

Weiqi Luo , Kendall A. Johnson , Clive H. Bock +3 more | Phytopathology

Phony peach disease (PPD), caused by Xylella fastidiosa subsp. multiplex (Xfm), poses a significant threat to commercial peach orchards in Georgia. Early and accurate detection is essential for effective disease … Phony peach disease (PPD), caused by Xylella fastidiosa subsp. multiplex (Xfm), poses a significant threat to commercial peach orchards in Georgia. Early and accurate detection is essential for effective disease management, yet visual assessment remains the primary approach for diagnosing PPD symptoms due to the high cost and logistical challenges of qPCR-based detection of Xfm. We evaluated the accuracy of visual PPD assessment and examined the factors influencing rater performance, symptom reliability, and optimal survey deployment strategies with CART/Random Forest analyses and simulations. Internode length was the most reliable symptom for PPD identification in two peach cultivars, consistently outperforming other physical traits such as canopy flatness and shape. Primer pair C06Xf-bamA had the greatest relative sensitivity, making it the preferred choice for qPCR confirmation. Principal component analysis suggested that rater experience significantly improved agreement with qPCR results and repeated assessments of the same orchards further enhanced consistency for raters. Simulations results suggested that deploying two experienced raters may provide the highest detection diagnostic accuracy for survey purposes, particularly when qPCR-based pathogen detection is unavailable. Last, PPD-affected trees, through PCR verification and visual identification, exhibited higher mortality rates than Xfm-negative trees, reinforcing the need for early detection and removal to limit disease spread. These findings underscore the importance of strategic rater deployment, targeted symptom selection, and integrating molecular diagnostics when feasible.

Molecular Identification and Genotyping of Phytoplasmas Infecting Medicinal and Aromatic Plants in Northern Italy

2025-06-21

Camilla Barbieri , Abdelhameed Moussa , Alessandro Passera +3 more | Microorganisms

During field surveys carried out in 2021 at two farms in Lombardy (North Italy), leaf samples were collected from 113 plants (both symptomatic and asymptomatic) belonging to 18 medicinal and … During field surveys carried out in 2021 at two farms in Lombardy (North Italy), leaf samples were collected from 113 plants (both symptomatic and asymptomatic) belonging to 18 medicinal and aromatic species. Amplification and nucleotide sequence analyses of the 16S rRNA gene revealed the presence of ‘Candidatus Phytoplasma solani’ (subgroup 16SrXII-A) in 69 plants (61% infection rate) belonging to 14 of the 18 examined species. Among the 14 infected species, only Nepeta cataria L. exhibited symptoms including leaf and stem reddening. Molecular typing analyses showed that ‘Ca. P. solani’ strains identified in this study constitute a genetically homogeneous population, carrying the stamp gene sequence variant St5 and the new vmp1 gene sequence variant Vm93. Phylogenetic analyses showed that ‘Ca. P. solani’ strain St5/Vm93 belongs to the cluster b-II, associated with the bindweed-related pathosystem. In silico-translated Vmp1 protein sequence alignment suggested that ‘Ca. P. solani’ strain St5/Vm93 could be generated by recombination events between ‘Ca. P. solani’ strains co-infecting the same host. The results suggested future research investigating the diffusion and the ecology of ‘Ca. P. solani’ strain St5/Vm93 in agroecosystems (including other crops), and its effect on the composition of biologically active compounds in aromatic and medicinal plants.

Dependence of the Abundance of Reed Glass-Winged Cicadas (Pentastiridius leporinus (Linnaeus, 1761)) on Weather and Climate in the Upper Rhine Valley, Southwest Germany

2025-06-19

Sai Kiran Kakarla , Eric Schall , Anna Dettweiler +7 more | Agriculture

The planthopper Pentastiridius leporinus, commonly called reed glass-winged cicada, transmits the pathogens “Candidatus Arsenophonus phytopathogenicus” and “Candidatus Phytoplasma solani”, which are infesting sugar beet and, most recently, also potato in … The planthopper Pentastiridius leporinus, commonly called reed glass-winged cicada, transmits the pathogens “Candidatus Arsenophonus phytopathogenicus” and “Candidatus Phytoplasma solani”, which are infesting sugar beet and, most recently, also potato in the Upper Rhine valley area of Germany. They cause the “Syndrome Basses Richesses” associated with reduced yield and sugar content in sugar beet, leading to substantial monetary losses to farmers in the region. No effective solutions exist currently. This study uses statistical models to understand to what extent the abundance of cicadas depends on climate regions during the vegetation period (April–October). We further investigated what influence temperature and precipitation have on the abundance of the cicadas in sugar beet fields. Furthermore, we investigated the possible impacts of future climate on cicada abundance. Also, 22 °C and 8 mm/day were found to be the optimal temperature and precipitation conditions for peak male cicada flight activity, while 28 °C and 8 mm/day were the optimum for females. By the end of the 21st century, daily male cicada abundance is projected to increase significantly under the worst-case high greenhouse gas emission scenario RCP8.5 (RCP-Representative Concentration Pathways), with confidence intervals suggesting a possible 5–15-fold increase compared to current levels. In contrast, under the low-emission scenario RCP2.6, male cicada populations are projected to be 60–70% lower than RCP8.5. An understanding of the influence of changing temperature and precipitation conditions is crucial for predicting the spread of this pest to different regions of Germany and other European countries.

An outbreak of beet leafhopper-transmitted virescence agent and Spiroplasma citri in cabbage (Brassica oleracea var. capitata) and Brussels sprouts (B. oleracea var. gemmifera) grown in the Columbia Basin of Oregon

2025-06-18

Hannah M. Rivedal , Todd N. Temple , Scott B. Lukas +3 more | Plant Health Progress

Mollicutes transmitted by beet leafhoppers (Circulifer tenellus) can be yield-limiting in a range of crops including hemp, potatoes, carrots and cole crops (Brassica oleracea). In 2021, both Candidatus Phytoplasma trifolii, … Mollicutes transmitted by beet leafhoppers (Circulifer tenellus) can be yield-limiting in a range of crops including hemp, potatoes, carrots and cole crops (Brassica oleracea). In 2021, both Candidatus Phytoplasma trifolii, a beet leafhopper-transmitted virescence agent, and Spiroplasma citri were detected in cole crops in Morrow County Oregon. This report details the molecular identification efforts for both pathogens. The confirmation of both mycoplasmas in cabbage and Brussels sprouts in the Columbia Basin may have management implications for vegetable and hemp producers in the region.

Foliar Spray of Macronutrient Influences Fruit Quality of Sugar Belle® Mandarin Grown in Florida Sandy Soil

2025-06-18

Sailesh Shrestha , Laura Waldo , Arnold W. Schumann | Agronomy

Sugar Belle® mandarin is considered tolerant to Huanglongbing (HLB); however, recent reports have raised concerns about its fruit quality, noting issues such as reduced fruit size, thin peel, poor coloration, … Sugar Belle® mandarin is considered tolerant to Huanglongbing (HLB); however, recent reports have raised concerns about its fruit quality, noting issues such as reduced fruit size, thin peel, poor coloration, decreased firmness, and suboptimal juice quality. Two-year field experiments were conducted to improve external and internal fruit characteristics through foliar application of potassium (K) in five-year-old Sugar Belle mandarin grown in Florida sandy soil. The experiment consisted of foliar K supply (17 kg/ha) via Potassium Nitrate (PN, 4.7 kg/ha N), Dipotassium Phosphate (DKP, 12.7 kg/ha P2O5), PN with boron (PNB, 0.84 kg/ha B) at different application times (May, July, September), including one-time Gibberellic acid spray (GA@10 mg/L) and control treatments. PN application during July (PNJ) or two applications of PN with B during May and July (PNBMJ) resulted in a larger fruit size (>65 mm). Results showed that PN application before fall (May or July) resulted in a significantly thicker peel (2.3 mm), 1.15 fold more than the control and GA treatment. Fruit puncture resistance force was significantly higher (33.1 N) with GA treatment (p = 0.07), followed by PNBMJ (32.6 N). Meanwhile, K spray positively influenced juice qualities and peel color, regardless of application time or source. However, GA treatment significantly reduced juice quality and peel color. These findings highlighted the benefits of foliar K supply as PN to improve fruit qualities in HLB-affected citrus grown in sandy soil.

Morphological-based phylogeny and revision of Ciminius Metcalf and Bruner, 1936 (Hemiptera, Cicadellidae)

2025-06-18

LUÍSA ALASMAR , Alexandre Cruz Domahovski , Rodney Ramiro Cavichioli | Arthropod Systematics & Phylogeny

In a morphological-based analysis using implied weighting for 23 taxa and 50 characters, we provided a phylogenetic study for Ciminius . The genus was recovered as monophyletic with a high … In a morphological-based analysis using implied weighting for 23 taxa and 50 characters, we provided a phylogenetic study for Ciminius . The genus was recovered as monophyletic with a high support. We also provided a taxonomic revision, with description of three new species, increasing the diversity of Ciminius from seven to ten species: the Neotropical C. albolineatus , C. callosa , C. platensis , C. yana , C. autumnalis sp. nov. , C. dissidens sp. nov. , C. sesamum sp. nov. , and the Nearctic C. hartii , C. sidanus , and C. taosus . A new monotypic genus, Arcanus gen. nov. , recovered as sister to Ciminius is described. Tylozygus Fieber, the new genus, and Ciminius were recovered forming a clade here nominated as Articulate Stem Clade, due to its unique connective morphology amongst all Cicadellini. The immature stages of Ciminius sp. are described and a key to males, an occurrence map, and notes of parasitism and submacroptery are provided. We discussed the Ciminius relationships according to our analysis, the genus distribution, and the taxonomic problems about C. callosa .

Spittlebugs vs predators: the importance of incidental vibrations for the detection of threats by insect vectors of Xylella fastidiosa

2025-06-17

Giada Spadavecchia , Erica Tinelli , Rachele Nieri +6 more | Journal of Pest Science

Phylogenomic and super‐pangenome analyses unveil the genetic landscape of tomato evolution and domestication

2025-06-15

Jingyin Yu , Qionglin Chen , Yuan Lü +7 more | Plant Biotechnology Journal

Summary The tomato ( Solanum lycopersicum L.), a principal fruit crop, exhibits significant genetic diversity shaped by domestication and breeding. Analysis of the gene‐based super‐pangenome, a catalogue of all genes … Summary The tomato ( Solanum lycopersicum L.), a principal fruit crop, exhibits significant genetic diversity shaped by domestication and breeding. Analysis of the gene‐based super‐pangenome, a catalogue of all genes across diverse genome‐sequenced tomatoes, has not yet been fully explored. Here, we present a comprehensive analysis of the gene‐based super‐pangenome across 61 genetically diverse tomato varieties, revealing 59 066 orthologous groups, thereby providing a detailed genetic framework for understanding the evolution of tomatoes. Our phylogenetic analysis recalibrates the position of S. galapagense , challenging existing paradigms of tomato evolution. Identification of genes linked to key agronomic traits such as fruit size, ripening and stress tolerance, along with their presence/absence variation among accessions, offers a rich source of genetic markers for breeding programs. The study also highlights the impact of whole‐genome triplication (WGT) and tandem gene duplication (TD) events on gene family expansion, particularly in distant wild relatives. The analysis of the LRR‐RLK gene family, important for plant development and defence, reveals substantial sequence diversity and conservation. Rapidly evolving genes and those under positive selection, such as HAI3, CYP711A1/MAX1, WRKY9 and CNGC15, are implicated in stress tolerance and defence mechanisms. The identification of these genes, along with specific pathogenesis‐related genes in distant wild relatives, suggests potential strategies to improve fruit shelf life, fruit set and stress tolerance in elite tomato cultivar breeding. Additionally, we have developed the tomatoPangenome platform, integrating genomic and pangenomic data, gene families and tools, to support sustainable production of high‐quality, climate‐resilient tomatoes and advance selective breeding for future food security.

Origin, Divergence and Migration Routes of Psyllids of the Cacopsylla pruni Complex (Hemiptera: Psylloidea) Inferred by Approximate Bayesian Computation Methods

2025-06-14

Margaux Darnis , Virginie Ravigné , Nicolas Sauvion | Journal of Biogeography

ABSTRACT Aim Population genetics is essential to decipher the evolutionary history of pests and insect vectors from both a theoretical point of view and to predict and mitigate the future … ABSTRACT Aim Population genetics is essential to decipher the evolutionary history of pests and insect vectors from both a theoretical point of view and to predict and mitigate the future of epidemics. We attempt to shed light on the evolutionary history and phylogeography of two cryptic psyllid species (namely, A and B) of the Cacopsylla pruni complex, vectors of ‘C andidatus Phytoplasma prunorum’. The bacterium is known to cause the European stone fruit yellows (ESFY), a disease affecting Prunus trees and causing significant crop losses. Analyses were conducted to decipher the origin, order and time of divergence, as well as the migration routes of the species complex on the scale of their current distribution area. Location Western Palearctic. Time Period Late Tertiary (i.e., the Neogene: 23.030–2.588 Mya) to today. Taxon Psyllids, jumping plantlice. Methods Our study was conducted on a dataset of 97 geolocated sampling points, representing a total of 1245 individuals from all across the Western Palearctic. We used mitochondrial and nuclear gene data to infer the population genetic diversity and structure of the complex and to reconstruct a dated phylogenetic tree of the Psyllinae family in order to subsequently perform Approximate Bayesian Computation analyses. Results Both species have diverged in what is now France from a common ancestor, around 20.19 Mya, before expanding into Spain around 6.61 Mya for species A and Eastern Europe around 6.36 Mya for species B. Then species B seems to have moved to Corsica during the Messinian salinity crisis (5.96–5.33 Mya) from French or Italian B populations. Main Conclusions No apparent admixture was found between both species after their divergence from France, which would indicate an absence of gene flow between them at the point when they recolonised common ecological niches. This strong genetic differentiation confirms previous work on reproductive barriers between the two species.

Multilocus Sequence Typing of “Candidatus Phytoplasma Solani” and Detection of <scp>RNA</scp> Viruses Infecting Cucurbits in the Marmara Region, Türkiye

2025-06-10

Filiz Randa Zelyüt , Ali Karanfil | Plant Pathology

ABSTRACT The stolbur disease associated with “ Candidatus Phytoplasma solani” (CaPsol) is very common in Europe and the Mediterranean regions and adversely affects perennial or annual plants but is rarely … ABSTRACT The stolbur disease associated with “ Candidatus Phytoplasma solani” (CaPsol) is very common in Europe and the Mediterranean regions and adversely affects perennial or annual plants but is rarely reported on cucurbits. We report the first multilocus genetic characterisation of CaPsol strains infecting cucurbit plants and the presence of some RNA viruses prevalent in cucurbits. Between 2019 and 2020, 156 symptomatic and nine asymptomatic plant samples were collected during surveys in cucurbit‐growing areas. Symptomatic plants exhibited leaf deformation, growth retardation, yellowing, flower deformation and other virus‐like symptoms. Molecular testing detected potyviruses, tobamoviruses and Cucumis melo endornavirus (CmEV) as single and double infections in 108 samples, but CaPsol was determined only in seven plants as a single infection. CaPsol strains infecting squash and watermelon in the Marmara region of Türkiye were genetically characterised by describing their tuf, vmp1 and stamp gene sequences. All cucurbit‐associated CaPsol strains were of the tuf ‐b1 genotype and five different stamp genotypes previously reported in other crops and wild plant reservoirs in Europe. Cucurbit CaPsol strains had vmp1 gene sequences corresponding to RFLP types V4 and V14, previously detected in the Mediterranean basin. These strains were not novel cucurbit‐specific genotypes but shared similarities with genotypes from diverse plant hosts across Europe. This indicated that CaPsol is not restricted to cucurbits and may persist in alternative plant hosts. Thus, disease management should include monitoring alternative plant reservoirs, rather than focusing solely on cucurbit production areas. Viral infections showed significantly higher prevalence compared to phytoplasma infections in the region.

Spread of <scp>Xylella fastidiosa</scp> in Majorca Island Agroecosystems: Interaction Between Insect Vectors, Woody Hosts and Bacterial Subspecies

2025-06-08

Miquel Llompart , Miquela Alomar , J Q Rolando Ortega +4 more | Plant Pathology

ABSTRACT Xylella fastidiosa (XF) is a gram‐negative bacterium naturally transmitted by xylem sap‐feeding insects that causes serious plant diseases. Since 2016, three subspecies of XF have been identified in Majorca: … ABSTRACT Xylella fastidiosa (XF) is a gram‐negative bacterium naturally transmitted by xylem sap‐feeding insects that causes serious plant diseases. Since 2016, three subspecies of XF have been identified in Majorca: fastidiosa , multiplex , and pauca . Only the Aphrophoridae Philaenus spumarius (PS) and Neophilaenus campestris (NC) have been reported as potential insect vectors for XF in Majorca and the Balearic Islands. This study aims to understand the spread of XF and propose effective and feasible strategies for its control. Eight plots were studied from 2019 to 2021: four almond orchards and four vineyards. The crops and the surrounding vegetation were sampled for XF, phytoplasmas, and potential vectors. DNA from plants and insects was extracted and amplified by three quantitative PCR (qPCR) methods, allowing subspecies identification. The results confirmed the prevalence of PS on the island, with also the presence of NC at lower levels. During the summer months, PS captures were mainly in the wild woody vegetation surrounding the crops. Of the total PS captures, 22.83% tested positive for XF, while 12.24% of NC specimens also tested positive for XF. Phytoplasma detection was also performed on captured Auchenorrhyncha insect species and plants, with all samples testing negative. These results confirm that PS is the main vector of XF on Majorca Island, both in terms of captures and the percentage of positive insects for XF. PS remains infective primarily on wild hosts throughout the summer, making it a difficult target for insecticide treatments on the crops.

Extracellular Vesicles From Xylella fastidiosa Carry sRNAs and Genomic Islands, Suggesting Roles in Recipient Cells

2025-06-01

Alessa Ruf , Patrick Blumenkamp , Christina Ludwig +7 more | Journal of Extracellular Vesicles

ABSTRACT Xylella fastidiosa ( Xf ) is a Gram‐negative bacterial plant pathogen responsible for severe diseases in a variety of economically important crops. A critical aspect of its virulence is … ABSTRACT Xylella fastidiosa ( Xf ) is a Gram‐negative bacterial plant pathogen responsible for severe diseases in a variety of economically important crops. A critical aspect of its virulence is the production of extracellular vesicles (EVs). In this study, we discovered that DNA‐binding proteins and nonribosomal RNA‐binding proteins are abundant in the corona of Xf ‐EVs. DNA‐seq revealed enrichment of three genomic islands (GIs) in EVs, which carry molecular signatures indicative of horizontal gene transfer (HGT). The most abundant GI encodes five homologous small RNAs designated sXFs . RNA sequencing revealed a distinct pattern of noncoding RNAs enriched in EVs, including four island‐encoded sXFs . One of the sXF ’s stem‐loops contains motifs for binding the RNA chaperone Hfq, which is also abundant in EVs. Predicted target analysis suggests that sXFs play a role in regulation of natural competence in bacteria. Additionally, sXF plant target prediction identifies a coiled‐coil nucleotide‐binding domain leucine‐rich repeat receptor ( CNL ) immune gene that is downregulated following Xf infection and Xf ‐EV treatment. We propose a model where Xf releases nucleic acid carrying EVs with two functions: one to deliver RNA‐related cargo that regulates gene expression in both bacterial and plant cells, and another to deliver DNA‐related cargo for the genetic transfer of genomic islands. We highlight island‐encoded sXFs as potential virulence factors and vesiduction as a mechanism of HGT of sXFs in Xf . Taken together, our data on Xf ‐EV cargoes provide a molecular framework for understanding the virulence of Xf .

AI-identified peptides boost jasmonate-mediated natural resistance against citrus Huanglongbing

2025-06-01

Zhibo Zhao , Sheng Du , Daowen Wang +2 more | Science Bulletin

The invasive leafhopper Amrasca biguttula (Ishida, 1913) in our garden: first report in Martinique (Hemiptera, Cicadellidae)

2025-06-01

Eddy Dumbardon-Martial , Chloé Pierre | Bulletin de la Société entomologique de France

Présence de la cicadelle invasive Amrasca biguttula dans notre jardin : premier signalement en Martinique (Hemiptera, Cicadellidae). La cicadelle du coton Amrasca biguttula (Ishida, 1913) a été récemment signalée à … Présence de la cicadelle invasive Amrasca biguttula dans notre jardin : premier signalement en Martinique (Hemiptera, Cicadellidae). La cicadelle du coton Amrasca biguttula (Ishida, 1913) a été récemment signalée à Puerto-Rico et à Barbade (les Antilles). La présence de cette espèce invasive en Martinique laisse penser qu’elle est établie dans les îles de la Caraïbe depuis plusieurs années. Il est probable que cet insecte constitue un risque sanitaire important pour les cultures maraîchères de Martinique.

Das Rätsel um Xylella fastidiosa und die Immunität des Olivenbaums

2025-06-01

Silke Robatzek , Natalie do Valle Capelli , Constance Tisserant | BIOspektrum

Novel insights showing SecA protein localization and distribution of phytoplasma in insect vector Empoasca paraparvipenis

2025-06-01

Kai Qiao , Fan Su , Huang Wei-yi +4 more | International Journal of Biological Macromolecules

How Xylella fastidiosa subsp. pauca influences endophytic communities and plant physiology in resistant and susceptible olive tree cultivars

2025-06-01

Marzia Vergine , Federico Vita , Mariarosaria De Pascali +6 more | Plant Stress

Anatomical and dual transcriptomic analysis reveals the interaction of “Candidatus Liberibacter asiaticus” and citrus host in new shoots at different growth stage

2025-06-01

Jiaming Li , Jinghan Chen , Wenxia Huang +5 more | Horticultural Plant Journal

Complete genome sequence data of Xylella fastidiosa subspecies multiplex ST88 and ST89 indicate distinct introductions in France

2025-06-01

Amandine Cunty , Jessica Dittmer , Déborah Merda +7 more | Data in Brief

Diagnosis of ‘Ca. Phytoplasma mali’ infection, and nutrient deficiencies in Malus domestica trees via in vivo spectroscopy

2025-06-01

Cameron Cullinan , Anna Scomparin , Massimo Tagliavini +1 more | Acta Horticulturae

SmartGrape – toward early detection of invasive cicada-borne grapevine diseases through in-field spectroscopy and plant volatile sensing

2025-06-01

L. Bertschinger , Meredith C. Schuman , L. Reichert +7 more | Acta Horticulturae

Host plants of Pochazia shantungensis (Hemiptera: Ricaniidae) in Wakayama Prefecture, Japan

2025-05-31

Masahiro Iguchi , Hiroshi Kodama | Annual Report of The Kansai Plant Protection Society

Molecular Characterization and DNA Barcoding of Black Gram Pod Borers from Andhra Pradesh, India

2025-05-31

Debasree Bhowmik , M. Rajasri , K. Devaki +1 more | Legume Research - An International Journal

Background: Four different pod borers species viz., Spotted pod borer (Maruca vitrata), Tobacco cutworm (Spodoptera litura), Gram blue butterfly (Euchrysops cnejus) and Banner moth (Eublemma dimidialis) were collected from black … Background: Four different pod borers species viz., Spotted pod borer (Maruca vitrata), Tobacco cutworm (Spodoptera litura), Gram blue butterfly (Euchrysops cnejus) and Banner moth (Eublemma dimidialis) were collected from black gram fields of Tirupati district, Andhra Pradesh. Methods: Molecular characterization of mtCOI sequences of the four black gram pod borer species were deposited in NCBI and accession numbers were allotted, M. vitrata (PP938848), S. litura (PP938758), E. cnejus (PP938841) and E. dimidialis (PP938850) respectively. DNA barcodes were generated and BINs were allotted for four different pod borers and available at BOLD public database. Result: The phylogenetic analysis of all the pod borers together revealed that the pod borer species were distinctly separated at genus level and were grouped into congeneric clusters. The DNA barcode of E. dimidialis (BOLD:AAB6502) was generated for the first time from India and the DNA barcode of E. cnejus (BOLD:AAD0845) was generated for the first time from Andhra Pradesh, India.

The Psylloidea (Hemiptera) of Portugal (mainland, Azores and Madeira): checklist and new distributional and host records

2025-05-29

Beatriz Duarte , Daniel Burckhardt , David Ouvrard +3 more | Zootaxa

The occurrence of 71 species of Psylloidea in Portugal (mainland and islands) is documented based on a critical review of literature sources and the examination of recently collected and museum … The occurrence of 71 species of Psylloidea in Portugal (mainland and islands) is documented based on a critical review of literature sources and the examination of recently collected and museum material. The following 17 species are reported from Portugal for the first time: Acizzia acaciaebaileyanae, Aphalara polygoni, Arytaina genistae, Arytainilla delarbrei, Bactericera nigricornis, B. substriola, B. trisignata, Cacopsylla alaterni, C. perrieri, Colposcenia tamaricis, Livia mediterranea, Livilla maculipennis, Macrohomotoma gladiata, Psylla foersteri, Psyllopsis fraxinicola, Trioza centranthi and T. eugeniae. Among the literature records reviewed, four are questionably assigned to particular psyllid genera or species, two probably refer to psyllids and six probably do not concern psyllids. Five species records in the literature are erroneous even though some of the species may occur in Portugal. The following synonymies are proposed: Bactericera Puton, 1876, = Phylloplecta Riley, 1884, syn. nov., = Sinitrioza Yang & Li, in Li & Yang, 1984, syn. nov. These synonymies entail following new or revived combinations: Bactericera chunghsingica Lauterer, Yang & Fang, 1988, comb. rev.; B. occidentalis (Tuthill, 1939) comb. nov.; B. rubicola (Tuthill, 1943) comb. nov.; B. rubisuga (Yang & Li, in Li & Yang, 1984) comb. nov.; B. stylifera (Patch, 1912) comb. nov.; B. tripunctata (Fitch, 1851) comb. nov. and B. trisignata (Löw, 1886) comb. rev. While the fauna of Madeira is relatively well documented, this is not the case for that of the Azores and particularly of the mainland.

First Report of 'Candidatus Phytoplasma trifolii'-related strain Association with Little Leaf and Declining Disease of Pulasan (Nephelium mutabile Blume) in Kerala, India

2025-05-29

A. Sajeena , Shivani Gupta , Govind P. Rao +5 more | Plant Disease

Pulasan (Nephelium mutabile Blume; family Sapindaceae) is a tropical fruit known for its high orilagin, ascorbic acid and thiamine content, known for its potent antioxidant and anti-inflammatory properties. Native to … Pulasan (Nephelium mutabile Blume; family Sapindaceae) is a tropical fruit known for its high orilagin, ascorbic acid and thiamine content, known for its potent antioxidant and anti-inflammatory properties. Native to Southeast Asia, pulasan is extensively cultivated in Malaysia, Thailand, Indonesia, Sri Lanka, India and Philippines (Afzaal et al., 2023). In India, pulasan is cultivated in tropics, where it is cherished as a homestead crop. A recent survey conducted in September 2024 at Pangode village (8°45'23.22"N 76°58'48.68"E), Thiruvananthapuram, Kerala, showed little leaf symptoms along with drying of side branches along with stunted growth in pulasan trees (variety P15). Only two pulasan trees were recorded with symptoms out of 20 trees examined in the campus. To investigate the molecular identity of the phytoplasma, leaf samples from two symptomatic and asymptomatic trees were collected and subjected to total DNA extraction by DNA extraction kit (Qiazen). The extracted DNA was amplified using nested PCR assays with universal primers P1/Tint (Smart et al., 1996) followed by 3Fwd/3Rev (Manimekalai et al., 2010) specific for the 16S rRNA gene and tuf gene-specific primer pairs fTufl/rTufl (Schneider et al., 1997). The PCR assays yielded amplicons of ~1.3 kb and ~1.1 kb for the 16S rRNA and tuf genes, respectively, from all the symptomatic leaf samples, whereas no amplification was observed from any asymptomatic samples. One sequence of each gene of pulasan phytoplasma strain (PK-1) were deposited into the GenBank database [(Acc Nos. PQ865399 (16S rRNA gene) and PQ877893 (tuf gene)]. BLASTn analysis of the both gene sequences of the PK strains revealed a 99.62% sequence identity with eggplant little leaf (Acc. No. MW273757; 16S rRNA gene) and 100% sequence similarity with Cucurbita pepo phytoplasma (Acc. No. KX358589; tuf gene) belongs to the clover proliferation phytoplasma subgroup. Phylogenetic analysis using MEGA 11 employing the Maximum likelihood method, demonstrated that the PK phytoplasma strains clustered within the 16SrVI-D subgroup-related strains. The virtual RFLP pattern generated for the 16S rRNA gene of PK phytoplasma strain through pDRAW analysis was found identical to the reference pattern of 16VI-D subgroup (Periwinkle little leaf phytoplasma; GenBank Acc. No. AF228053). Sequence comparison analysis confirmed the presence of a 'Candidatus Phytoplasma trifolii'-related strain associated with pulasan showing little leaf disease and stunting in India. While, phytoplasma associations have been reported in various fruit species globally (Fiore et al., 2018; Mitra et al., 2023), this study represents the first documented case of a phytoplasma disease infecting pulasan worldwide. Notably, 'Ca. P. trifolii' (16SrVI-D subgroup) has previously been identified associated with several economically important agricultural and horticultural crops worldwide (Zhao and Wei, 2020; Rao, 2021). The results of this study revealed that pulasan trees serve as an alternative natural reservoir for the ‘Candidatus Phytoplasma trifolii’ (16SrVI-D) phytoplasma strain, may potentially facilitate its dissemination to other crops through insect vectors. Considering the significant phytosanitary concerns, epidemiological factors and economic impact of pulasan in Southeast Asia for its global export potential, the detection of phytoplasma-associated disease in pulasan is noteworthy as it not only poses a potential threat to cultivation and productivity but may also have broader implications for regional trade and biosecurity protocols.

Multicenter Retrospective Study of Spiroplasma ixodetis Infantile Cataract in 8 Countries in Europe

2025-05-28

Luc Van Os , Nathalie Cassoux , Symira Cholidis +7 more | Emerging infectious diseases

Spiroplasma ixodetis has been reported to cause the rare combination of cataract and uveitis in infants. Through a retrospective analysis of available literature and additional unpublished cases, we identified 28 … Spiroplasma ixodetis has been reported to cause the rare combination of cataract and uveitis in infants. Through a retrospective analysis of available literature and additional unpublished cases, we identified 28 eyes from 18 infants from 8 countries in Europe with cataracts and intraocular inflammation. The cataracts were bilateral in 55.6%, unilateral in 44.4%, and progressive in 46.4% of patients. Granulomatous anterior uveitis was found in all infants. Presence of S. ixodetis was supported by PCR (positive in 89.3% of eyes tested), transmission electron microscopy (positive in 90% of eyes tested), or culture of aspirated lens material (positive in 87.5% of eyes tested). Treatment with macrolide antimicrobial drugs, corticosteroids, and lensectomy appeared to be effective. Two patients had a recurrence of the uveitis after lens extraction and needed prolonged treatment. To increase awareness of S. ixodetis, we suggest its inclusion with the organisms of the TORCH acronym.

Genomic footprint of a shared Type 5 prophage in 'Candidatus Liberibacter asiaticus' and 'Candidatus Liberibacter africanus', two destructive bacterial pathogens of citrus huanglongbing

2025-05-28

Frédéric Labbé , C. Boyer , Fernando Clavijo-Coppens +4 more | bioRxiv (Cold Spring Harbor Laboratory)

Huanglongbing (HLB) is a bacterial disease that affects citrus trees and is considered the most severe citrus disease in the world. The three HLB-associated 'Ca. Liberibacter' species harbor prophage regions … Huanglongbing (HLB) is a bacterial disease that affects citrus trees and is considered the most severe citrus disease in the world. The three HLB-associated 'Ca. Liberibacter' species harbor prophage regions which have been described to play critical roles in their evolution and biology. In this study, we assembled and characterized the accessory genome of the first circular de novo 'Candidatus Liberibacter asiaticus' (CLas) assembly (V1R1) from Réunion, one of the sparse areas worldwide hosting CLas and 'Ca. Liberibacter africanus' (CLaf). This 1,272 Mb-long whole-genome harbored 1,129 coding sequences and two complete prophages, including a 37,934 bp-long Type 1 prophage, frequently present in CLas genomes, and a 40,501 bp-long undescribed CLas prophage designated as P-V1R1-5. Comparative genomic approaches suggested that P-V1R1-5 have all the genetic elements to produce new viral particles and revealed that it likely belongs to a new CLas Type 5 prophage. While being reported for the first time in a CLas strain, P-V1R1-5-like prophages were previously identified in CLaf genomes, making it the first evidence of shared prophage-like sequence among HLB-associated 'Ca, Liberibacter' species. Using PCR amplifications targeting P-V1R1-5, we also showed that 85.7% of the tested CLas strains from Réunion and all tested CLaf strains from Madagascar and Réunion harbored a Type 5-like prophage. The identification of CLas Type 5-like prophages not only expanded our knowledge of CLas genomic diversity in Réunion, but also provided new insights into the role of horizontally transferred elements in the evolution of the sympatric HLB-associated bacteria.

A list of the Fulgoroidea (Homoptera) of southern Illinois.

1980-01-01

Sw Wilson , J. E. McPherson