Agricultural and Biological Sciences › Plant Science

Plant Pathogenic Bacteria Studies

Works Count: 43828

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Description

This cluster of papers focuses on the genomics, pathogenicity, and host interactions of plant pathogenic bacteria, particularly in the context of bacterial blight in rice and other crops. It covers topics such as type III secretion systems, effector proteins, resistance genes, and the molecular mechanisms underlying host specificity. The research also delves into the genomics and evolution of specific bacterial pathogens such as Pseudomonas syringae and Ralstonia solanacearum.

Keywords

Plant Pathogenic Bacteria; Genomics; Type III Secretion System; Bacterial Blight; Host Specificity; Effector Proteins; Rice Resistance Genes; Phyllosphere Pathogens; Pseudomonas syringae; Ralstonia solanacearum

Pseudomonasgenomes: diverse and adaptable

2011-03-03

Mark W. Silby , Craig Winstanley , Scott A. C. Godfrey +2 more

Members of the genus Pseudomonas inhabit a wide variety of environments, which is reflected in their versatile metabolic capacity and broad potential for adaptation to fluctuating environmental conditions. Here, we … Members of the genus Pseudomonas inhabit a wide variety of environments, which is reflected in their versatile metabolic capacity and broad potential for adaptation to fluctuating environmental conditions. Here, we examine and compare the genomes of a range of Pseudomonas spp. encompassing plant, insect and human pathogens, and environmental saprophytes. In addition to a large number of allelic differences of common genes that confer regulatory and metabolic flexibility, genome analysis suggests that many other factors contribute to the diversity and adaptability of Pseudomonas spp. Horizontal gene transfer has impacted the capability of pathogenic Pseudomonas spp. in terms of disease severity (Pseudomonas aeruginosa) and specificity (Pseudomonas syringae). Genome rearrangements likely contribute to adaptation, and a considerable complement of unique genes undoubtedly contributes to strain- and species-specific activities by as yet unknown mechanisms. Because of the lack of conserved phenotypic differences, the classification of the genus has long been contentious. DNA hybridization and genome-based analyses show close relationships among members of P. aeruginosa, but that isolates within the Pseudomonas fluorescens and P. syringae species are less closely related and may constitute different species. Collectively, genome sequences of Pseudomonas spp. have provided insights into pathogenesis and the genetic basis for diversity and adaptation.

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Molecular characterization of cloned avirulence genes from race 0 and race 1 of Pseudomonas syringae pv. glycinea

1987-12-01

Brian J. Staskawicz , Douglas Dahlbeck , N. T. Keen +1 more

A wide-host-range cosmid cloning vector, pLAFR3, was constructed and used to make cosmid libraries of partially digested Sau3A DNA from race 0 and race 1 of Pseudomonas syringae pv. glycinea. … A wide-host-range cosmid cloning vector, pLAFR3, was constructed and used to make cosmid libraries of partially digested Sau3A DNA from race 0 and race 1 of Pseudomonas syringae pv. glycinea. Two avirulence genes, avrB0 and avrC, cloned from race 0, elicited the hypersensitivity reaction (HR) on specific cultivars of soybean. Race 4 transconjugants containing avrB0 induced a dark brown necrotic HR within 24 h on the soybean cultivars Harosoy and Norchief, whereas race 4 transconjugants containing avrC induced a light brown necrotic HR within 48 h on the soybean cultivars Acme, Peking, Norchief, and Flambeau. An additional avirulence gene, avrB1, cloned from race 1, appeared to be identical to avrB0 from race 0. The avrB0 and avrC genes from race 0 were characterized by restriction enzyme mapping, Southern blot analysis, Tn5 transposon mutagenesis, and site-directed gene replacements. The effects of these three genes on the in planta bacterial growth of race 4 transconjugants have also been examined. The identification and cloning of avrB1 provides genetic evidence for a gene-for-gene interaction in the bacterial blight disease of soybean, as avrB1 from race 1 interacts with the soybean disease resistance locus, Rpg1.

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Specific genomic fingerprints of phytopathogenic Xanthomonas and Pseudomonas pathovars and strains generated with repetitive sequences and PCR

1994-07-01

Frank J. Louws , Dennis W. Fulbright , C. T. Stephens +1 more

DNA primers corresponding to conserved motifs in bacterial repetitive (REP, ERIC, and BOX) elements and PCR were used to show that REP-, ERIC-, and BOX-like DNA sequences are widely distributed … DNA primers corresponding to conserved motifs in bacterial repetitive (REP, ERIC, and BOX) elements and PCR were used to show that REP-, ERIC-, and BOX-like DNA sequences are widely distributed in phytopathogenic Xanthomonas and Pseudomonas strains. REP-, ERIC, and BOX-PCR (collectively known as rep-PCR) were used to generate genomic fingerprints of a variety of Xanthomonas and Pseudomonas isolates and to identify pathovars and strains that were previously not distinguishable by other classification methods. Analogous rep-PCR-derived genomic fingerprints were generated from purified genomic DNA, colonies on agar plates, liquid cultures, and directly from lesions on infected plants. REP, ERIC, and BOX-PCR-generated fingerprints of specific Xanthomonas and Pseudomonas strains were found to yield similar conclusions wtih regard to the identity of and relationship between these strains. This suggests that the distribution of REP-, ERIC, and BOX-like sequences in these strains is a reflection of their genomic structure. Thus, the rep-PCR technique appears to be a rapid, simple, and reproducible method to identify and classify Xanthomonas and Pseudomonas strains, and it may be a useful diagnostic tool for these important plant pathogens.

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Hypersensitive response-related death.

2000-01-01

Michèle C. Heath

Clusters of Resistance Genes in Plants Evolve by Divergent Selection and a Birth-and-Death Process

1998-11-01

Richard W. Michelmore , Blake C. Meyers

Classical genetic and molecular data show that genes determining disease resistance in plants are frequently clustered in the genome. Genes for resistance ( R genes) to diverse pathogens cloned from … Classical genetic and molecular data show that genes determining disease resistance in plants are frequently clustered in the genome. Genes for resistance ( R genes) to diverse pathogens cloned from several species encode proteins that have motifs in common. These motifs indicate that R genes are part of signal-transduction systems. Most of these R genes encode a leucine-rich repeat (LRR) region. Sequences encoding putative solvent-exposed residues in this region are hypervariable and have elevated ratios of nonsynonymous to synonymous substitutions; this suggests that they have evolved to detect variation in pathogen-derived ligands. Generation of new resistance specificities previously had been thought to involve frequent unequal crossing-over and gene conversions. However, comparisons between resistance haplotypes reveal that orthologs are more similar than paralogs implying a low rate of sequence homogenization from unequal crossing-over and gene conversion. We propose a new model adapted and expanded from one proposed for the evolution of vertebrate major histocompatibility complex and immunoglobulin gene families. Our model emphasizes divergent selection acting on arrays of solvent-exposed residues in the LRR resulting in evolution of individual R genes within a haplotype. Intergenic unequal crossing-over and gene conversions are important but are not the primary mechanisms generating variation.

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Chromosomal genetics of Pseudomonas

1979-03-01

B. W. Holloway , V. Krishnapillai , A F Morgan

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Principles and Applications of Methods for DNA-Based Typing of Microbial Organisms

1999-06-01

D Olive , Pamela Bean

Outbreaks of infectious disease often result from exposure to a common source of the etiologic agent. Generally, the etiologic agent causing an outbreak of infection is derived from a single … Outbreaks of infectious disease often result from exposure to a common source of the etiologic agent. Generally, the etiologic agent causing an outbreak of infection is derived from a single cell whose progeny are genetically identical or closely related to the source organism. In epidemiological terms, the organisms involved in the outbreak are clonally related; that is, they have a common origin. Clonally related organisms are members of the same species that share virulence factors, biochemical traits, and genomic characteristics. However, there is sufficient diversity at the species level that organisms isolated from different sources at different times and in different geographical regions may be differentiated or classified into subtypes or strains.

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Top 10 plant pathogenic bacteria in molecular plant pathology

2012-06-05

John W. Mansfıeld , Stéphane Genin , Shimpei Magori +7 more

SUMMARY Many plant bacteriologists, if not all, feel that their particular microbe should appear in any list of the most important bacterial plant pathogens. However, to our knowledge, no such … SUMMARY Many plant bacteriologists, if not all, feel that their particular microbe should appear in any list of the most important bacterial plant pathogens. However, to our knowledge, no such list exists. The aim of this review was to survey all bacterial pathologists with an association with the journal Molecular Plant Pathology and ask them to nominate the bacterial pathogens they would place in a ‘Top 10’ based on scientific/economic importance. The survey generated 458 votes from the international community, and allowed the construction of a Top 10 bacterial plant pathogen list. The list includes, in rank order: (1) Pseudomonas syringae pathovars; (2) Ralstonia solanacearum ; (3) Agrobacterium tumefaciens ; (4) Xanthomonas oryzae pv . oryzae ; (5) Xanthomonas campestris pathovars; (6) Xanthomonas axonopodis pathovars; (7) Erwinia amylovora ; (8) Xylella fastidiosa ; (9) Dickeya (dadantii and solani) ; (10) Pectobacterium carotovorum (and Pectobacterium atrosepticum ). Bacteria garnering honourable mentions for just missing out on the Top 10 include Clavibacter michiganensis ( michiganensis and sepedonicus ), Pseudomonas savastanoi and Candidatus Liberibacter asiaticus . This review article presents a short section on each bacterium in the Top 10 list and its importance, with the intention of initiating discussion and debate amongst the plant bacteriology community, as well as laying down a benchmark. It will be interesting to see, in future years, how perceptions change and which bacterial pathogens enter and leave the Top 10.

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Initiation of RPS2-Specified Disease Resistance in Arabidopsis Is Coupled to the AvrRpt2-Directed Elimination of RIN4

2003-02-01

Michael J. Axtell , Brian J. Staskawicz

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Common Virulence Factors for Bacterial Pathogenicity in Plants and Animals

1995-06-30

Laurence G. Rahme , Emily J. Stevens , Sean F. Wolfort +3 more

A Pseudomonas aeruginosa strain (UCBPP-PA14) is infectious both in an Arabidopsis thaliana leaf infiltration model and in a mouse full-thickness skin burn model. UCBPP-PA14 exhibits ecotype specificity for Arabidopsis , … A Pseudomonas aeruginosa strain (UCBPP-PA14) is infectious both in an Arabidopsis thaliana leaf infiltration model and in a mouse full-thickness skin burn model. UCBPP-PA14 exhibits ecotype specificity for Arabidopsis , causing a range of symptoms from none to severe in four different ecotypes. In the mouse model, UCBPP-PA14 is as lethal as other well-studied P. aeruginosa strains. Mutations in the UCBPP-PA14 toxA , plcS , and gacA genes resulted in a significant reduction in pathogenicity in both hosts, indicating that these genes encode virulence factors required for the full expression of pathogenicity in both plants and animals.

Breaking the Code of DNA Binding Specificity of TAL-Type III Effectors

2009-10-30

Jens Boch , Heidi Scholze , Sebastián Schornack +6 more

The pathogenicity of many bacteria depends on the injection of effector proteins via type III secretion into eukaryotic cells in order to manipulate cellular processes. TAL (transcription activator-like) effectors from … The pathogenicity of many bacteria depends on the injection of effector proteins via type III secretion into eukaryotic cells in order to manipulate cellular processes. TAL (transcription activator-like) effectors from plant pathogenic Xanthomonas are important virulence factors that act as transcriptional activators in the plant cell nucleus, where they directly bind to DNA via a central domain of tandem repeats. Here, we show how target DNA specificity of TAL effectors is encoded. Two hypervariable amino acid residues in each repeat recognize one base pair in the target DNA. Recognition sequences of TAL effectors were predicted and experimentally confirmed. The modular protein architecture enabled the construction of artificial effectors with new specificities. Our study describes the functionality of a distinct type of DNA binding domain and allows the design of DNA binding domains for biotechnology.

Genome sequence of the plant pathogen Ralstonia solanacearum

2002-01-01

Marcel Salanoubat , Stéphane Genin , François Artiguenave +7 more

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Initiation of Plant Disease Resistance by Physical Interaction of AvrPto and Pto Kinase

1996-12-20

Xiaoyan Tang , Reid D. Frederick , Jian‐Min Zhou +3 more

Resistance to bacterial speck disease in tomato occurs when the Pto kinase in the plant responds to expression of the avirulence gene avrPto in the Pseudomonas pathogen. Transient expression of … Resistance to bacterial speck disease in tomato occurs when the Pto kinase in the plant responds to expression of the avirulence gene avrPto in the Pseudomonas pathogen. Transient expression of an avrPto transgene in plant cells containing Pto elicited a defense response. In the yeast two-hybrid system, the Pto kinase physically interacted with AvrPto. Alterations of AvrPto or Pto that disrupted the interaction in yeast also abolished disease resistance in plants. The physical interaction of AvrPto and Pto provides an explanation of gene-for-gene specificity in bacterial speck disease resistance.

The complete genome sequence of the Arabidopsis and tomato pathogen Pseudomonas syringae pv. tomato DC3000

2003-08-19

C. Robin Buell , Vinita Joardar , Magdalen Lindeberg +7 more

We report the complete genome sequence of the model bacterial pathogen Pseudomonas syringae pathovar tomato DC3000 (DC3000), which is pathogenic on tomato and Arabidopsis thaliana . The DC3000 genome (6.5 … We report the complete genome sequence of the model bacterial pathogen Pseudomonas syringae pathovar tomato DC3000 (DC3000), which is pathogenic on tomato and Arabidopsis thaliana . The DC3000 genome (6.5 megabases) contains a circular chromosome and two plasmids, which collectively encode 5,763 ORFs. We identified 298 established and putative virulence genes, including several clusters of genes encoding 31 confirmed and 19 predicted type III secretion system effector proteins. Many of the virulence genes were members of paralogous families and also were proximal to mobile elements, which collectively comprise 7% of the DC3000 genome. The bacterium possesses a large repertoire of transporters for the acquisition of nutrients, particularly sugars, as well as genes implicated in attachment to plant surfaces. Over 12% of the genes are dedicated to regulation, which may reflect the need for rapid adaptation to the diverse environments encountered during epiphytic growth and pathogenesis. Comparative analyses confirmed a high degree of similarity with two sequenced pseudomonads, Pseudomonas putida and Pseudomonas aeruginosa , yet revealed 1,159 genes unique to DC3000, of which 811 lack a known function.

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Protein delivery into eukaryotic cells by type III secretion machines

2006-11-01

Jorge E. Galán , Hans Wolf‐Watz

A Receptor Kinase-Like Protein Encoded by the Rice Disease Resistance Gene, Xa21

1995-12-15

W. H. Song , Guo‐Liang Wang , Li-Li Chen +7 more

The rice Xa21 gene, which confers resistance to Xanthomonas oryzae pv. oryzae race 6, was isolated by positional cloning. Fifty transgenic rice plants carrying the cloned Xa21 gene display high … The rice Xa21 gene, which confers resistance to Xanthomonas oryzae pv. oryzae race 6, was isolated by positional cloning. Fifty transgenic rice plants carrying the cloned Xa21 gene display high levels of resistance to the pathogen. The sequence of the predicted protein, which carries both a leucine-rich repeat motif and a serine-threonine kinase-like domain, suggests a role in cell surface recognition of a pathogen ligand and subsequent activation of an intracellular defense response. Characterization of Xa21 should facilitate understanding of plant disease resistance and lead to engineered resistance in rice.

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Proposal of Burkholderia gen. nov. and Transfer of Seven Species of the Genus Pseudomonas Homology Group II to the New Genus, with the Type Species Burkholderia cepacia (Palleroni and Holmes 1981) comb. nov.

1992-12-01

Eiko Yabuuchi , Yoshimasa Kosako , Hiroshi Oyaizu +5 more

Abstract Based on the 16S rRNA sequences, DNA‐DNA homology values, cellular lipid and fatty acid composition, and phenotypic characteristics, a new genus Burkholderia is proposed for the RNA homology group … Abstract Based on the 16S rRNA sequences, DNA‐DNA homology values, cellular lipid and fatty acid composition, and phenotypic characteristics, a new genus Burkholderia is proposed for the RNA homology group II of genus Pseudomonas . Seven species in this group were transfered to the new genus. Thus seven new combinations, Burkholderia cepacia (Palleroni and Holmes 1981), Burkholderia mallei (Zopf 1885), Burkholderia pseudomallei (Whitmore 1913), Burkholderia caryophylli (Burkholder 1942), Burkholderia gladioli (Severini 1913), Burkholderia pickettii (Ralston et al 1973) and Burkholderia solanacearum (Smith 1896) were proposed.

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Harpin, Elicitor of the Hypersensitive Response Produced by the Plant Pathogen Erwinia amylovora

1992-07-03

Zhongmin Wei , Ron J. Laby , Cathy H. Zumoff +4 more

A proteinaceous elicitor of the plant defense reaction known as the hypersensitive response was isolated from Erwinia amylovora , the bacterium that causes fire blight of pear, apple, and other … A proteinaceous elicitor of the plant defense reaction known as the hypersensitive response was isolated from Erwinia amylovora , the bacterium that causes fire blight of pear, apple, and other rosaceous plants. The elicitor, named harpin, is an acidic, heat-stable, cell-envelope-associated protein with an apparent molecular weight of 44 kilodaltons. Harpin caused tobacco leaf lamina to collapse and caused an increase in the pH of bathing solutions of suspension-cultured tobacco cells. The gene encoding harpin ( hrpN ) was located in the 40-kilobase hrp gene cluster of E. amylovora , sequenced, and mutated with Tn 5 tac1. The hrpN mutants were not pathogenic to pear, did not elicit the hypersensitive response, and did not produce harpin.

A Simple Cipher Governs DNA Recognition by TAL Effectors

2009-10-30

Matthew Moscou , Adam J. Bogdanove

TAL Order Xanthomonas bacteria attack their plant hosts by delivering their own transcription-activator–like (TAL) proteins into the plant cell nucleus and alter the plant's gene regulation (see the Perspective by … TAL Order Xanthomonas bacteria attack their plant hosts by delivering their own transcription-activator–like (TAL) proteins into the plant cell nucleus and alter the plant's gene regulation (see the Perspective by Voytas and Joung ). Moscou and Bogdanove (p. 1501 , published online 29 October: see the cover) and Boch et al. (p. 1509 , published online 29 October) have now discovered how the similar but not identical repeats in the TAL proteins encode the specificity needed for the proteins to find their targets. Each repeat is specific for one DNA base pair, a specificity encoded by hypervariable amino acid positions. Combining several repeats with different amino acids in the hypervariable positions allowed the production of new effectors that targeted new DNA sites.

Physical interaction between RRS1-R, a protein conferring resistance to bacterial wilt, and PopP2, a type III effector targeted to the plant nucleus

2003-06-03

Laurent Deslandes , J. Olivier , Nemo Peeters +6 more

RRS1-R confers broad-spectrum resistance to several strains of the causal agent of bacterial wilt, Ralstonia solanacearum. Although genetically defined as recessive, this R gene encodes a protein whose structure combines … RRS1-R confers broad-spectrum resistance to several strains of the causal agent of bacterial wilt, Ralstonia solanacearum. Although genetically defined as recessive, this R gene encodes a protein whose structure combines the TIR-NBS-LRR domains found in several R proteins and a WRKY motif characteristic of some plant transcriptional factors and behaves as a dominant gene in transgenic susceptible plants. Here we show that PopP2, a R. solanacearum type III effector, which belongs to the YopJ/AvrRxv protein family, is the avirulence protein recognized by RRS1-R. Furthermore, an interaction between PopP2 and both RRS1-R and RRS1-S, present in the resistant Nd-1 and susceptible Col-5 Arabidopsis thaliana ecotypes, respectively, was detected by using the yeast split-ubiquitin two-hybrid system. This interaction, which required the full-length R protein, was not observed between the RRS1 proteins and PopP1, another member of the YopJ/AvrRxv family present in strain GMI1000 and that confers avirulence in Petunia. We further demonstrate that both the Avr protein and the RRS1 proteins colocalize in the nucleus and that the nuclear localization of the RRS1 proteins are dependent on the presence of PopP2.

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A Determinative Scheme for the Fluorescent Plant Pathogenic Pseudomonads

1966-12-01

R. A. Lelliott , E. Billing , Andrew Hayward

S ummary . The differential value of 15 characteristics was studied for the determination of plant pathogens in the fluorescent group of the genus Pseudomonas. All but 2 of the … S ummary . The differential value of 15 characteristics was studied for the determination of plant pathogens in the fluorescent group of the genus Pseudomonas. All but 2 of the 161 pathogenic cultures and the 15 nonpathogenic cultures examined could be placed in one of 5 groups on the basis of tests for: oxidase, potato soft rot, arginine dihydrolase, levan production and a hypersensitivity reaction in tobacco leaves. Tests for production of acid from sucrose, nitrate reductase and a lipase for margarine were useful as subsidiary determinants. Aesculin hydrolysis, gelatinase and tyrosinase tests, and the production of a blue fluorescent pigment were of little or no value at the group level, and hydrolysis of Tween 80 and the catalase reaction had no differential value. With the exception of Ps. tolaaii and two cultures of questionable pathogenicity, the pathogens studied could be separated readily from the few nonpathogens studied. A determinative scheme for plant pathogenic fluorescent pseudomonads is proposed to serve until the taxonomy of the group is better understood.

Xanthomonas oryzae pathovars: model pathogens of a model crop

2006-08-31

David Niño-Liu , Pamela C. Ronald , Adam J. Bogdanove

SUMMARY Xanthomonas oryzae pv. oryzae and Xanthomonas oryzae pv. oryzicola cause bacterial blight and bacterial leaf streak of rice (Oryza sativa), which constrain production of this staple crop in much … SUMMARY Xanthomonas oryzae pv. oryzae and Xanthomonas oryzae pv. oryzicola cause bacterial blight and bacterial leaf streak of rice (Oryza sativa), which constrain production of this staple crop in much of Asia and parts of Africa. Tremendous progress has been made in characterizing the diseases and breeding for resistance. X. oryzae pv. oryzae causes bacterial blight by invading the vascular tissue, while X. oryzae pv. oryzicola causes bacterial leaf streak by colonizing the parenchyma. In rice there are 29 major genes for resistance to bacterial blight, but so far only a few quantitative resistance loci for bacterial leaf streak. Over 30 races of X. oryzae pv. oryzae have been reported. Both pathogens exhibit genetic variation among isolates. Mechanisms of pathogenesis and resistance have begun to be elucidated. Members of the AvrBs3/PthA family of transcription activator-like effectors play a major role in the virulence of X. oryzae pv. oryzae and possibly X. oryzae pv. oryzicola. Cloning of six rice resistance genes for bacterial blight and one from maize effective against bacterial leaf streak has uncovered a diversity of structure and function, some shared by genes involved in defence in animals. This article reviews research that spans a century. It also presents a perspective on challenges for sustainable control, and opportunities that interactions of X. oryzae pathovars with rice present as models for understanding fundamental aspects of bacterial pathogenesis of plants and plant disease resistance, as well as other aspects of plant and microbial biology, with implications also for animal innate immunity.

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The rhizosphere as a reservoir for opportunistic human pathogenic bacteria

2005-08-24

Gabriele Berg , Leo Eberl , Anton Hartmann

Summary During the last years, the number of human infections caused by opportunistic pathogens has increased dramatically. One natural reservoir of opportunistic pathogens is the rhizosphere, the zone around roots … Summary During the last years, the number of human infections caused by opportunistic pathogens has increased dramatically. One natural reservoir of opportunistic pathogens is the rhizosphere, the zone around roots that is influenced by the plant. Due to a high content of nutrients, this habitat is a ‘microbial hot‐spot’, where bacterial abundances including those with strong antagonistic traits are enhanced. Various bacterial genera, including Burkholderia , Enterobacter , Herbaspirillum , Ochrobactrum , Pseudomonas , Ralstonia , Staphylococcus and Stenotrophomonas , contain root‐associated strains that can encounter bivalent interactions with both plant and human hosts. Mechanisms responsible for colonization of the rhizosphere and antagonistic activity against plant pathogens are similar to those responsible for colonization of human organs and tissues, and pathogenicity. Multiple resistances against antibiotics are not only found with clinical strains but also with strains isolated from the rhizosphere. High competition, the occurrence of diverse antibiotics in the rhizosphere, and enhanced horizontal gene transfer rates in this microenvironment appear to contribute to the high levels of natural resistances. While opportunistic bacteria from the rhizosphere have some properties in common, each of these emerging pathogens has its own features, which are discussed in detail for Burkholderia , Ochrobactrum and Stenotrophomonas .

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Bacteria in the Leaf Ecosystem with Emphasis onPseudomonas syringae—a Pathogen, Ice Nucleus, and Epiphyte

2000-09-01

Susan S. Hirano , Christen D. Upper

SUMMARY The extremely large number of leaves produced by terrestrial and aquatic plants provide habitats for colonization by a diversity of microorganisms. This review focuses on the bacterial component of … SUMMARY The extremely large number of leaves produced by terrestrial and aquatic plants provide habitats for colonization by a diversity of microorganisms. This review focuses on the bacterial component of leaf microbial communities, with emphasis on Pseudomonas syringae—a species that participates in leaf ecosystems as a pathogen, ice nucleus, and epiphyte. Among the diversity of bacteria that colonize leaves, none has received wider attention than P. syringae, as it gained notoriety for being the first recombinant organism (Ice − P. syringae) to be deliberately introduced into the environment. We focus on P. syringae to illustrate the attractiveness and somewhat unique opportunities provided by leaf ecosystems for addressing fundamental questions of microbial population dynamics and mechanisms of plant-bacterium interactions. Leaf ecosystems are dynamic and ephemeral. The physical environment surrounding phyllosphere microbes changes continuously with daily cycles in temperature, radiation, relative humidity, wind velocity, and leaf wetness. Slightly longer-term changes occur as weather systems pass. Seasonal climatic changes impose still a longer cycle. The physical and physiological characteristics of leaves change as they expand, mature, and senesce and as host phenology changes. Many of these factors influence the development of populations of P. syringae upon populations of leaves. P. syringae was first studied for its ability to cause disease on plants. However, disease causation is but one aspect of its life strategy. The bacterium can be found in association with healthy leaves, growing and surviving for many generations on the surfaces of leaves as an epiphyte. A number of genes and traits have been identified that contribute to the fitness of P. syringae in the phyllosphere. While still in their infancy, such research efforts demonstrate that the P. syringae-leaf ecosystem is a particularly attractive system with which to bridge the gap between what is known about the molecular biology of genes linked to pathogenicity and the ecology and epidemiology of associated diseases as they occur in natural settings, the field.

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Ecology of the Soft Rot Erwinias

1980-09-01

M. C. M. Pérombelon , A. Kelman

Beneficial microbes in the microbiome of plant roots improve plant health. Induced systemic resistance (ISR) emerged as an important mechanism by which selected plant growth–promoting bacteria and fungi in the … Beneficial microbes in the microbiome of plant roots improve plant health. Induced systemic resistance (ISR) emerged as an important mechanism by which selected plant growth–promoting bacteria and fungi in the rhizosphere prime the whole plant body for ...Read More

R<scp>ESISTANCE</scp>G<scp>ENE</scp>C<scp>OMPLEXES</scp>: Evolution and Utilization

2001-09-01

Scot H. Hulbert , Craig A. Webb , Shavannor M. Smith +1 more

▪ Abstract More than 30 genes have been characterized from different plant species that provide resistance to a variety of different pathogen and pest species. The structures of most are … ▪ Abstract More than 30 genes have been characterized from different plant species that provide resistance to a variety of different pathogen and pest species. The structures of most are consistent with a role in pathogen recognition and defense response signaling. Resistance genes are very abundant in plant genomes and most belong to tightly linked gene families. Evolution of R genes is driven by selection on allelic variation created by mutation and re-assorted by recombination between alleles and sometimes between different gene family members. Selection favors genes that can recognize pathogen avr gene products that are present in pathogen populations. Selection at linked gene families favors haplotypes with useful combinations of genes but a limited physiological cost to the plant. Future utilization of R genes will include transfer between related genera and identification or construction of genes that condition durable resistance to variable pathogens. Genes with durable resistance may interact with conserved pathogen elicitors or condition resistance responses that are independent of specific Avr gene interactions.

Identification of Pseudomonas syringae pathogens of Arabidopsis and a bacterial locus determining avirulence on both Arabidopsis and soybean.

1991-01-01

Maureen C. Whalen , Roger W. Innes , Andrew F. Bent +1 more

To develop a model system for molecular genetic analysis of plant-pathogen interactions, we studied the interaction between Arabidopsis thaliana and the bacterial pathogen Pseudomonas syringae pv tomato (Pst). Pst strains … To develop a model system for molecular genetic analysis of plant-pathogen interactions, we studied the interaction between Arabidopsis thaliana and the bacterial pathogen Pseudomonas syringae pv tomato (Pst). Pst strains were found to be virulent or avirulent on specific Arabidopsis ecotypes, and single ecotypes were resistant to some Pst strains and susceptible to others. In many plant-pathogen interactions, disease resistance is controlled by the simultaneous presence of single plant resistance genes and single pathogen avirulence genes. Therefore, we tested whether avirulence genes in Pst controlled induction of resistance in Arabidopsis. Cosmids that determine avirulence were isolated from Pst genomic libraries, and the Pst avirulence locus avrRpt2 was defined. This allowed us to construct pathogens that differed only by the presence or absence of a single putative avirulence gene. We found that Arabidopsis ecotype Col-0 was susceptible to Pst strain DC3000 but resistant to the same strain carrying avrRpt2, suggesting that a single locus in Col-0 determines resistance. As a first step toward genetically mapping the postulated resistance locus, an ecotype susceptible to infection by DC3000 carrying avrRpt2 was identified. The avrRpt2 locus from Pst was also moved into virulent strains of the soybean pathogen P. syringae pv glycinea to test whether this locus could determine avirulence on soybean. The resulting strains induced a resistant response in a cultivar-specific manner, suggesting that similar resistance mechanisms may function in Arabidopsis and soybean.

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Assembly and Function of Type III Secretory Systems

2000-10-01

Guy R. Cornelis , Frédérique Van Gijsegem

▪ Abstract Type III secretion systems allow Yersinia spp., Salmonella spp., Shigella spp., Bordetella spp., and Pseudomonas aeruginosa and enteropathogenic Escherichia coli adhering at the surface of a eukaryotic cell … ▪ Abstract Type III secretion systems allow Yersinia spp., Salmonella spp., Shigella spp., Bordetella spp., and Pseudomonas aeruginosa and enteropathogenic Escherichia coli adhering at the surface of a eukaryotic cell to inject bacterial proteins across the two bacterial membranes and the eukaryotic cell membrane to destroy or subvert the target cell. These systems consist of a secretion apparatus, made of ∼25 proteins, and an array of proteins released by this apparatus. Some of these released proteins are “effectors,” which are delivered into the cytosol of the target cell, whereas the others are “translocators,” which help the effectors to cross the membrane of the eukaryotic cell. Most of the effectors act on the cytoskeleton or on intracellular-signaling cascades. A protein injected by the enteropathogenic E. coli serves as a membrane receptor for the docking of the bacterium itself at the surface of the cell. Type III secretion systems also occur in plant pathogens where they are involved both in causing disease in susceptible hosts and in eliciting the so-called hypersensitive response in resistant or nonhost plants. They consist of 15–20 Hrp proteins building a secretion apparatus and two groups of effectors: harpins and avirulence proteins. Harpins are presumably secreted in the extracellular compartment, whereas avirulence proteins are thought to be targeted into plant cells. Although a coherent picture is clearly emerging, basic questions remain to be answered. In particular, little is known about how the type III apparatus fits together to deliver proteins in animal cells. It is even more mysterious for plant cells where a thick wall has to be crossed. In spite of these haunting questions, type III secretion appears as a fascinating trans-kingdom communication device.

A<scp>NTIBIOTIC</scp> U<scp>SE IN</scp> P<scp>LANT</scp> A<scp>GRICULTURE</scp>

2002-09-01

Patricia S. McManus , Virginia O. Stockwell , George W. Sundin +1 more

▪ Abstract Antibiotics have been used since the 1950s to control certain bacterial diseases of high-value fruit, vegetable, and ornamental plants. Today, the antibiotics most commonly used on plants are … ▪ Abstract Antibiotics have been used since the 1950s to control certain bacterial diseases of high-value fruit, vegetable, and ornamental plants. Today, the antibiotics most commonly used on plants are oxytetracycline and streptomycin. In the USA, antibiotics applied to plants account for less than 0.5% of total antibiotic use. Resistance of plant pathogens to oxytetracycline is rare, but the emergence of streptomycin-resistant strains of Erwinia amylovora, Pseudomonas spp., and Xanthomonas campestris has impeded the control of several important diseases. A fraction of streptomycin-resistance genes in plant-associated bacteria are similar to those found in bacteria isolated from humans, animals, and soil, and are associated with transfer-proficient elements. However, the most common vehicles of streptomycin-resistance genes in human and plant pathogens are genetically distinct. Nonetheless, the role of antibiotic use on plants in the antibiotic-resistance crisis in human medicine is the subject of debate.

Pseudomonas syringaePhytotoxins: Mode of Action, Regulation, and Biosynthesis by Peptide and Polyketide Synthetases

1999-06-01

Carol L. Bender , Francisco Alarcón-Chaidez , Dennis C. Gross

SUMMARY Coronatine, syringomycin, syringopeptin, tabtoxin, and phaseolotoxin are the most intensively studied phytotoxins of Pseudomonas syringae, and each contributes significantly to bacterial virulence in plants. Coronatine functions partly as a … SUMMARY Coronatine, syringomycin, syringopeptin, tabtoxin, and phaseolotoxin are the most intensively studied phytotoxins of Pseudomonas syringae, and each contributes significantly to bacterial virulence in plants. Coronatine functions partly as a mimic of methyl jasmonate, a hormone synthesized by plants undergoing biological stress. Syringomycin and syringopeptin form pores in plasma membranes, a process that leads to electrolyte leakage. Tabtoxin and phaseolotoxin are strongly antimicrobial and function by inhibiting glutamine synthetase and ornithine carbamoyltransferase, respectively. Genetic analysis has revealed the mechanisms responsible for toxin biosynthesis. Coronatine biosynthesis requires the cooperation of polyketide and peptide synthetases for the assembly of the coronafacic and coronamic acid moieties, respectively. Tabtoxin is derived from the lysine biosynthetic pathway, whereas syringomycin, syringopeptin, and phaseolotoxin biosynthesis requires peptide synthetases. Activation of phytotoxin synthesis is controlled by diverse environmental factors including plant signal molecules and temperature. Genes involved in the regulation of phytotoxin synthesis have been located within the coronatine and syringomycin gene clusters; however, additional regulatory genes are required for the synthesis of these and other phytotoxins. Global regulatory genes such as gacS modulate phytotoxin production in certain pathovars, indicating the complexity of the regulatory circuits controlling phytotoxin synthesis. The coronatine and syringomycin gene clusters have been intensively characterized and show potential for constructing modified polyketides and peptides. Genetic reprogramming of peptide and polyketide synthetases has been successful, and portions of the coronatine and syringomycin gene clusters could be valuable resources in developing new antimicrobial agents.

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Arabidopsis RIN4 Is a Target of the Type III Virulence Effector AvrRpt2 and Modulates RPS2-Mediated Resistance

2003-02-01

David Mackey , Youssef Belkhadir , José M. Alonso +2 more

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Xanthomonas AvrBs3 Family-Type III Effectors: Discovery and Function

2010-07-01

Jens Boch , Ulla Bonas

Xanthomonads are bacterial plant pathogens that cause diseases on many plant species, including important crops. Key to pathogenicity of most Xanthomonas pathovars is a Hrp-type III secretion (T3S) system that … Xanthomonads are bacterial plant pathogens that cause diseases on many plant species, including important crops. Key to pathogenicity of most Xanthomonas pathovars is a Hrp-type III secretion (T3S) system that translocates effector proteins into plant cells. Within the eukaryotic cell, the effectors are thought to perform a variety of tasks to support bacterial virulence, proliferation, and dissemination. We are only beginning to understand the host targets of different effectors. The largest effector family found in Xanthomonas spp. is the AvrBs3/PthA or TAL (transcription activator-like) family. TAL effectors act as transcriptional activators in the plant cell nucleus. Specificity of TAL effectors is determined by a novel modular DNA-binding domain. Here, we describe the discovery of TAL effectors and their structure, activity, and host targets.

Reclassification of Xanthomonas

1995-07-01

L. Vauterin , Bart Hoste , K. Kersters +1 more

A comprehensive DNA-DNA hybridization study was performed by using 183 strains of the genus Xanthomonas. This genus was shown to comprise 20 DNA homology groups which are considered genomic species. … A comprehensive DNA-DNA hybridization study was performed by using 183 strains of the genus Xanthomonas. This genus was shown to comprise 20 DNA homology groups which are considered genomic species. Four groups corresponded to the previously described species Xanthomonas albilineans, Xanthomonas fragariae, Xanthomonas oryzae, and Xanthomonas populi. The previously described species Xanthomonas campestris was heterogeneous and was divided into 16 DNA homology groups. One of these groups exhibited a high level of DNA homology with Xanthomonas axonopodis. The 62 pathovars represented in this study were allocated to appropriate species. Our results, together with previous taxonomic data, supported a comprehensive revision of the classification of the genus Xanthomonas. The species X. albilineans, X. fragariae, X. oryzae, and X. populi are not affected. The type species of the genus, X. campestris (Pammel 1895) Dowson 1939, is emended to include only the pathovars obtained from crucifers (i.e., X. campestris pv. aberrans, X. campestris pv. armoraciae, X. campestris pv. barbareae, X. campestris pv. campestris, X. campestris pv. incanae, and X. campestris pv. raphani). X. axonopodis Starr and Garces 1950 is emended to include 34 former X. campestris pathovars. The following species names are proposed: Xanthomonas arboricola sp. nov., including X. arboricola pv. corylina, X. arboricola pv. juglandis, X. arboricola pv. poinsettiicola (type C strains of the former X. campestris pathovar), X. arboricola pv. populi, and X. arboricola pv. pruni; Xanthomonas bromi sp. nov. for strains isolated from bromegrass; Xanthomonas cassavae (ex Wiehe and Dowson 1953) sp. nov., nom. rev.; Xanthomonas codiaei sp. nov., including type B strains of the former taxon X. campestris pv. poinsettiicola; Xanthomonas cucurbitae (ex Bryan 1926) sp. nov., nom. rev.; Xanthomonas hortorum sp. nov., including X. hortorum pv. hederae, X. hortorum pv. pelargonii, and X. hortorum pv. vitians; Xanthomonas hyacinthi (ex Wakker 1883) sp. nov., nom. rev.; Xanthomonas melonis sp. nov.; Xanthomonas pisi (ex Goto and Okabe 1958) sp. nov., nom. rev.; Xanthomonas sacchari sp. nov. for strains isolated from diseased sugarcane in Guadeloupe; Xanthomonas theicola sp. nov.; Xanthomonas translucens (ex Jones, Johnson, and Reddy 1917) sp. nov., nom. rev., including X. translucens pv. arrhenatheri, X. translucens pv. cerealis, X. translucens pv. graminis, X. translucens pv. hordei, X. translucens pv. phlei, X. translucens pv. phleipratensis, X. translucens pv. poae, X. translucens pv. secalis, X. translucens pv. translucens, and X. translucens pv. undulosa; Xanthomonas vasicola sp. nov., including X. vasicola pv. holcicola and X. vasicola pv. vasculorum (type B strains of the former taxon X. campestris pv. vasculorum); and Xanthomonas vesicatoria (ex Doidge 1920) sp. nov., nom. rev., which includes the type B strains of the former taxon X. campestris pv. vesicatoria. Differentiating characteristics were determined for the new species on the basis of metabolic activity on a range of carbon substrates by using the Biolog GN microplate system.

TYPE III SECRETION SYSTEM EFFECTOR PROTEINS: Double Agents in Bacterial Disease and Plant Defense

2004-07-29

James R. Alfano , Alan Collmer

Many phytopathogenic bacteria inject virulence effector proteins into plant cells via a Hrp type III secretion system (TTSS). Without the TTSS, these pathogens cannot defeat basal defenses, grow in plants, … Many phytopathogenic bacteria inject virulence effector proteins into plant cells via a Hrp type III secretion system (TTSS). Without the TTSS, these pathogens cannot defeat basal defenses, grow in plants, produce disease lesions in hosts, or elicit the hypersensitive response (HR) in nonhosts. Pathogen genome projects employing bioinformatic methods to identify TTSS Hrp regulon promoters and TTSS pathway targeting signals suggest that phytopathogenic Pseudomonas, Xanthomonas, and Ralstonia spp. harbor large arsenals of effectors. The Hrp TTSS employs customized cytoplasmic chaperones, conserved export components in the bacterial envelope (also used by the TTSS of animal pathogens), and a more specialized set of TTSS-secreted proteins to deliver effectors across the plant cell wall and plasma membrane. Many effectors can act as molecular double agents that betray the pathogen to plant defenses in some interactions and suppress host defenses in others. Investigations of the functions of effectors within plant cells have demonstrated the plasma membrane and nucleus as subcellular sites for several effectors, revealed some effectors to possess cysteine protease or protein tyrosine phosphatase activity, and provided new clues to the coevolution of bacterium-plant interactions.

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Role of Stomata in Plant Innate Immunity and Foliar Bacterial Diseases

2008-04-18

Maeli Melotto , William Underwood , Sheng Yang He

Pathogen entry into host tissue is a critical first step in causing infection. For foliar bacterial plant pathogens, natural surface openings, such as stomata, are important entry sites. Historically, these … Pathogen entry into host tissue is a critical first step in causing infection. For foliar bacterial plant pathogens, natural surface openings, such as stomata, are important entry sites. Historically, these surface openings have been considered as passive portals of entry for plant pathogenic bacteria. However, recent studies have shown that stomata can play an active role in limiting bacterial invasion as part of the plant innate immune system. As a counter-defense, the plant pathogen Pseudomonas syringae pv. tomato DC3000 uses the virulence factor coronatine to actively open stomata. In nature, many foliar bacterial disease outbreaks require high humidity, rain, or storms, which could favor stomatal opening and/or bypass stomatal defense by creating wounds as alternative entry sites. Further studies on microbial and environmental regulation of stomatal closure and opening could fill gaps in our understanding of bacterial pathogenesis, disease epidemiology, and microbiology of the phyllosphere.

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Type III Secretion Machines: Bacterial Devices for Protein Delivery into Host Cells

1999-05-21

Jorge E. Galán , Alan Collmer

Several Gram-negative pathogenic bacteria have evolved a complex protein secretion system termed type III to deliver bacterial effector proteins into host cells that then modulate host cellular functions. These bacterial … Several Gram-negative pathogenic bacteria have evolved a complex protein secretion system termed type III to deliver bacterial effector proteins into host cells that then modulate host cellular functions. These bacterial devices are present in both plant and animal pathogenic bacteria and are evolutionarily related to the flagellar apparatus. Although type III secretion systems are substantially conserved, the effector molecules they deliver are unique for each bacterial species. Understanding the biology of these devices may allow the development of novel prevention and therapeutic approaches for several infectious diseases.

Biology and Epidemiology of Bacterial Wilt Caused by Pseudomonas Solanacearum

1991-09-01

Andrew Hayward

Bacterial wilt caused by Pseudomonas solanacearum is widely distributed in tropical, subtropical and some warm temperate regions of the world, and is a major constraint on production of many crop … Bacterial wilt caused by Pseudomonas solanacearum is widely distributed in tropical, subtropical and some warm temperate regions of the world, and is a major constraint on production of many crop plants. Major sections of this review are on: phylogeny (particularly using molecular biology), properties, relationships and geographical distribution; host range; modes of dispersal and sources of inoculum (including root-to-root transmission, movement of soil and dissemination by farm implements, and insect transmission); some environmental interactions (temperature - the most important factor affecting the host-pathogen interaction as well as survival in soils, light intensity, soil moisture (preferably high), soil type, and synergism with nematodes); and control strategies, especially development of host-plant resistance, appropriate cropping systems, soil amendment, disease avoidance, integrated control, and biological control using antagonistic rhizobacteria and avirulent mutants. -P.J.Jarvis

Rapid In Situ Assay for Indoleacetic Acid Production by Bacteria Immobilized on a Nitrocellulose Membrane

1991-02-01

John M. Bric , Richard M. Bostock , Sara E. Silverstone

We have developed a new assay that differentiates between indoleacetic acid (IAA)-producing and -nonproducing bacteria on a colony plate lift. Medium supplemented with 5 mM L-tryptophan is inoculated with isolates … We have developed a new assay that differentiates between indoleacetic acid (IAA)-producing and -nonproducing bacteria on a colony plate lift. Medium supplemented with 5 mM L-tryptophan is inoculated with isolates of interest, overlaid with a nitrocellulose membrane, and then incubated until bacterial colonies reach 1 to 2 mm in diameter. The membrane is removed to a filter paper saturated with Salkowski reagent and incubated until distinct red haloes form around the colonies. The colorimetric reaction to IAA is limited to a region immediately surrounding each colony, is specific to isolates producing IAA, occurs within 1 h after the membrane is placed in the reagent, and is sensitive to as little as 50 pmol of IAA in a 2-mm 2 spot. We have used this assay for quantifying epiphytic and endophytic populations of IAA-producing isolates of Pseudomonas syringae subsp. savastanoi and for detecting IAA-producing colonies of other pseudomonads and Erwinia herbicola . The assay provides a rapid and convenient method to screen large numbers of bacteria.

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Type IV Pili and Twitching Motility

2002-09-04

John S. Mattick

Twitching motility is a flagella-independent form of bacterial translocation over moist surfaces. It occurs by the extension, tethering, and then retraction of polar type IV pili, which operate in a … Twitching motility is a flagella-independent form of bacterial translocation over moist surfaces. It occurs by the extension, tethering, and then retraction of polar type IV pili, which operate in a manner similar to a grappling hook. Twitching motility is equivalent to social gliding motility in Myxococcus xanthus and is important in host colonization by a wide range of plant and animal pathogens, as well as in the formation of biofilms and fruiting bodies. The biogenesis and function of type IV pili is controlled by a large number of genes, almost 40 of which have been identified in Pseudomonas aeruginosa. A number of genes required for pili assembly are homologous to genes involved in type II protein secretion and competence for DNA uptake, suggesting that these systems share a common architecture. Twitching motility is also controlled by a range of signal transduction systems, including two-component sensor-regulators and a complex chemosensory system.

Type III Protein Secretion Systems in Bacterial Pathogens of Animals and Plants

1998-06-01

Christoph J. Hueck

SUMMARY Various gram-negative animal and plant pathogens use a novel, sec-independent protein secretion system as a basic virulence mechanism. It is becoming increasingly clear that these so-called type III secretion … SUMMARY Various gram-negative animal and plant pathogens use a novel, sec-independent protein secretion system as a basic virulence mechanism. It is becoming increasingly clear that these so-called type III secretion systems inject (translocate) proteins into the cytosol of eukaryotic cells, where the translocated proteins facilitate bacterial pathogenesis by specifically interfering with host cell signal transduction and other cellular processes. Accordingly, some type III secretion systems are activated by bacterial contact with host cell surfaces. Individual type III secretion systems direct the secretion and translocation of a variety of unrelated proteins, which account for species-specific pathogenesis phenotypes. In contrast to the secreted virulence factors, most of the 15 to 20 membrane-associated proteins which constitute the type III secretion apparatus are conserved among different pathogens. Most of the inner membrane components of the type III secretion apparatus show additional homologies to flagellar biosynthetic proteins, while a conserved outer membrane factor is similar to secretins from type II and other secretion pathways. Structurally conserved chaperones which specifically bind to individual secreted proteins play an important role in type III protein secretion, apparently by preventing premature interactions of the secreted factors with other proteins. The genes encoding type III secretion systems are clustered, and various pieces of evidence suggest that these systems have been acquired by horizontal genetic transfer during evolution. Expression of type III secretion systems is coordinately regulated in response to host environmental stimuli by networks of transcription factors. This review comprises a comparison of the structure, function, regulation, and impact on host cells of the type III secretion systems in the animal pathogens Yersinia spp., Pseudomonas aeruginosa, Shigella flexneri, Salmonella typhimurium, enteropathogenic Escherichia coli, and Chlamydia spp. and the plant pathogens Pseudomonas syringae, Erwinia spp., Ralstonia solanacearum, Xanthomonas campestris, and Rhizobium spp.

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Comparison of the genomes of two Xanthomonas pathogens with differing host specificities

2002-05-01

A. C. R. da Silva , Jesus Aparecido Ferro , Fernando C. Reinach +7 more

Genomics and taxonomy in diagnostics for food security: soft-rotting enterobacterial plant pathogens

2015-11-16

Leighton Pritchard , R. Glover , Sonia Humphris +2 more

Whole genome comparisons provide a quantitative, objective basis for taxonomic classification of bacterial pathogens important to food security. Whole genome comparisons provide a quantitative, objective basis for taxonomic classification of bacterial pathogens important to food security.

Laboratory Guide for identification of plant pathogenic bacteria

1981-01-01

P. J. Keane

An improved technique for evaluating resistance of rice varieties to Xanthomonas oryzae

1973-01-01

H. E. Kauffman , A. P. K. Reddy , Sungj-ching Hsieh +1 more

Xanthomonas citri MinC Oscillates from Pole to Pole to Ensure Proper Cell Division and Shape

2017-07-18

André S. G. Lorenzoni , Giordanni Cabral Dantas , Tessa Bergsma +2 more

Xanthomonas citri (Xac) is the causal agent of citrus canker, a disease that affects citrus crops and causes economic impact worldwide. To further characterize cell division in this plant pathogen, … Xanthomonas citri (Xac) is the causal agent of citrus canker, a disease that affects citrus crops and causes economic impact worldwide. To further characterize cell division in this plant pathogen, we investigated the role of the protein MinC in cell division, chromosome segregation, and peptidoglycan incorporation by deleting the gene minC using allele exchange. Xac with minC deleted exhibited the classic Δmin phenotype observed in other bacteria deleted for min components: minicells and short filamentation. In addition we noticed the formation of branches, which is similar to what was previously described for Escherichia coli deleted for either min or for several low molecular weight penicillin-binding proteins. The branching phenotype was medium dependent and probably linked to gluconeogenic growth. We complemented the minC gene by integrating gfp-minC into the amy locus. Xac complemented strains displayed a wild-type phenotype. In addition, GFP-MinC oscillated from pole to pole, similar to MinCD oscillations observed in E. coli and more recently in Synechococcus elongatus. Further investigation of the branching phenotype revealed that in branching cells nucleoid organization, divisome formation and peptidoglycan incorporation were disrupted.

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Pseudomonas syringae: what it takes to be a pathogen

2018-02-26

Xiu‐Fang Xin , Brian H. Kvitko , Sheng Yang He

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Transfer of Two Burkholderia and An Alcaligenes Species to Ralstonia Gen. Nov.

1995-11-01

Eiko Yabuuchi , Yoshimasa Kosako , Ikuya Yano +2 more

Abstract Based on the results of phenotypic characterization, cellular lipid and fatty acid analysis, phylogenetic analysis of 16S rDNA nucleotide sequences and rRNA‐DNA hybridization, Burkholderia pickettii, Burkholderia solanacearum and Alcaligenes … Abstract Based on the results of phenotypic characterization, cellular lipid and fatty acid analysis, phylogenetic analysis of 16S rDNA nucleotide sequences and rRNA‐DNA hybridization, Burkholderia pickettii, Burkholderia solanacearum and Alcaligenes eutrophus are transferred to the new genus Ralstonia , and Ralstonia pickettii (Ralston, Palleroni and Doudoroff 1973) comb. nov., Ralstonia solanacearum (Smith 1896) comb, nov., and R. eutropha (Davis 1969) comb. nov. are proposed. The type species of the new genus is R. pickettii . Type strain of R. pickettii is ATCC 27511 T , of R. solanacearum is ATCC 10696 T , and of R. eutropha is ATCC 17697 T .

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PLANT DISEASE RESISTANCE GENES

1997-06-01

K. E. Hammond‐Kosack , Jonathan D. G. Jones

In "gene-for-gene" interactions between plants and their pathogens, incompatibility (no disease) requires a dominant or semidominant resistance (R) gene in the plant, and a corresponding avirulence (Avr) gene in the … In "gene-for-gene" interactions between plants and their pathogens, incompatibility (no disease) requires a dominant or semidominant resistance (R) gene in the plant, and a corresponding avirulence (Avr) gene in the pathogen. Many plant/pathogen interactions are of this type. R genes are presumed to (a) enable plants to detect Avr-gene-specified pathogen molecules, (b) initiate signal transduction to activate defenses, and (c) have the capacity to evolve new R gene specificities rapidly. Isolation of R genes has revealed four main classes of R gene sequences whose products appear to activate a similar range of defense mechanisms. Discovery of the structure of R genes and R gene loci provides insight into R gene function and evolution, and should lead to novel strategies for disease control.

Molecular biological methods for bacillus

1991-08-05

M.C.M. Smith

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Kasugamycin disrupts membrane transport and reduces virulence in Pectobacterium aroidearum to control konjac soft rot

2025-06-26

Chunlan Xiong , Xue Zhou , Yupei Tu +4 more | Phytopathology Research

Abstract Konjac ( Amorphophallus konjac ) is an important food crop and a traditional medicinal herb in China. However, bacterial soft rot poses a serious threat to konjac production and … Abstract Konjac ( Amorphophallus konjac ) is an important food crop and a traditional medicinal herb in China. However, bacterial soft rot poses a serious threat to konjac production and quality. In this study, we identified Pectobacterium aroidearum as the causative pathogen of soft rot in konjac and investigated the antibacterial effects of kasugamycin (KSM) against this bacterium. Our results show that KSM exhibits strong antibacterial activity, significantly reducing the virulence of P. aroidearum and providing both protective and curative effects against konjac soft rot. Further mechanistic analysis reveal that KSM disrupts key gene expression associated with membrane transport in P. aroidearum , leading to inhibited swimming motility, reduced production of virulence factors, and significant alterations in cell morphology. These findings highlight the antibacterial properties of KSM against P. aroidearum , offering valuable insights into its potential application for treating bacterial soft rot in konjac.

Temporal dynamics of GFP- labeled Xanthomonas campestris pv. campestris in cauliflower: contrasting responses in resistant and susceptible genotypes to elicitor application

2025-06-25

Neelam Geat , Dinesh Singh , Devendra Singh +3 more | Journal of Plant Pathology

Bacterial Pustule Disease in Soybean: Occurrence, Host–Pathogen Interactions and Management

2025-06-25

Suyan Wang , Yong‐hui Jiang , Zi‐Yao Huo +7 more | Plant Pathology

ABSTRACT Bacterial pustule (BP) is a recurrent soybean disease caused by Xanthomonas citri pv. glycines (Xcg; X. axonopodis pv. glycines ; X. campestris pv. glycines ), resulting in soybean yield … ABSTRACT Bacterial pustule (BP) is a recurrent soybean disease caused by Xanthomonas citri pv. glycines (Xcg; X. axonopodis pv. glycines ; X. campestris pv. glycines ), resulting in soybean yield reductions of up to 60% under favourable conditions. Here, we review the reports regarding the occurrence, pathogen–host interactions and management of Xcg for the first time. BP was first reported in Sudan in 1956, and since 2005 the disease has spread in northern Thailand, the Madhya Pradesh and Maharashtra states of India and South Korea. Flagella biosynthesis genes flgK and flgB , outer membrane protein OmpA and transcriptional regulator LcrX, along with type II and III effector systems, play a key role in Xcg virulence. While Xcg growth depends on sugar absorption, excessive protein concentrations activate programmed cell death. Control efficacies higher than 70% were detected when applying the commercial antibiotic oxytetracycline, the bacterial biocontrol agents Pseudomonas parafulva JBCS1880 and Curtobacterium sp. M84, or the natural metabolites biochanin A and thymol. Some soybean cultivars, such as Daepung, BRS 205 and SS2‐2, have shown moderate–high resistance levels to Xcg; however, none of the cultivars were screened against various Xcg races. Currently, BP management relies on the application of antibiotics that are toxic to humans or the use of soybean cultivars with partial resistance. Overall, Xcg is a worldwide recurrent soybean pathogen that causes significant economic damage in wet and warm weather (30°C–33°C). Further research into the Xcg infection mechanism is essential to identify potential targets for BP management.

Pseudomonas gessardii suppresses Xanthomonas vesicatoria through 4-Dodecylbenzene sulfonic acid interference with virulence proteins

2025-06-25

Riddha Dey , Seema Devi , J. Prasad +3 more | World Journal of Microbiology and Biotechnology

Adaptative and ancient co-evolution of integrons with Xanthomonas genomes

2025-06-24

Elena Colombi , Timothy M. Ghaly , Vaheesan Rajabal +3 more

ABSTRACT Integrons are genetic elements that facilitate gene acquisition. They have been extensively studied in clinical bacteria, but their evolutionary role in phytopathogens remains underexplored. Here, we analysed complete genomes … ABSTRACT Integrons are genetic elements that facilitate gene acquisition. They have been extensively studied in clinical bacteria, but their evolutionary role in phytopathogens remains underexplored. Here, we analysed complete genomes of Xanthomonas species to investigate the origin, distribution, and functional dynamics of integrons in this genus. We found that 93% of genomes harboured integrons. The integron-integrase gene intI was predominantly located downstream of ilvD , indicating an ancestral acquisition of integrons, predating diversification within the genus. Phylogenetic analyses support vertical inheritance of intI , with the exception of rare horizontal gene transfer events, notably in X. arboricola . Despite their widespread presence, full-length intI genes and active integron platforms are only retained in some species, especially X. campestris , which shows high integron gene cassette variability and functional integron activity. In contrast, species such as X. cissicola and X. phaseoli exhibit widespread inI inactivation, likely occurring early in their divergence, leading to more stable cassette arrays and conserved integron-associated phenotypes. The number and diversity of genes within cassette arrays varied significantly by species and, to a lesser extent, by the ecological context of plant host cultivation. While most cassettes encoded proteins without a known function, those with annotated roles were associated with stress response mechanism, competitive exclusion, and plant-associated functions. Together, our findings demonstrate that integrons in Xanthomonas likely originated from a single ancient acquisition event, preceding genus-wide speciation, and have co-evolved with Xanthomonas pathovars as they adapted to distinct plant hosts. IMPACT STATEMENT This study provides the first comprehensive genus-wide analysis of integron evolution and dynamics in Xanthomonas , a globally distributed and versatile plant pathogen. Integrons are genetic platforms that allow horizontal transfer of genes. They are well characterised in human pathogens where they mediate transfer of antibiotic resistance genes, but little is known about their role in plant associated bacteria. We showed that in Xanthomonas the integron platform was ancestrally acquired, yet integrons have undergone repeated lineage-specific inactivation events. Despite widespread erosion of integron activity, some species such as X. campestris maintain robust and functionally diverse integrons that continue to shape genome plasticity. Notably, high cassette diversity, combined with the presence of rare and often uncharacterized genes within these arrays (some potentially involved in environmental sensing or host interaction) suggest that integrons may serve as reservoirs of adaptive potential. Our findings reshape current views of integron function beyond antibiotic resistance and highlight their long-term role in microbial evolution, niche adaptation, and genome innovation in plant-associated bacteria. DATA SUMMARY The authors confirm all supporting data, code and protocols have been provided within the article or through supplementary data files.

Silica Cross-Linked Micelles as Pesticide Nanocarriers for Effective Treatment of Xanthomonas oryzae pv Oryzae Infection

2025-06-24

Yuting Cai , Wenjun Mu , Wenyan Ding +3 more | ACS Applied Nano Materials

Dickeya ananatis sp. nov., pectinolytic bacterium isolated from pineapple (Ananas comosus)

2025-06-24

Shefali Dobhal , Nicole Hugouvieux‐Cotte‐Pattat , Dario Arizala +4 more | INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY

Species clustering within Dickeya zeae has been recently identified as complex, encompassing validly published names, including Dickeya oryzae and Dickeya parazeae , with some strains potentially delineating new species. In … Species clustering within Dickeya zeae has been recently identified as complex, encompassing validly published names, including Dickeya oryzae and Dickeya parazeae , with some strains potentially delineating new species. In this study, genomes of strains isolated from bacterial heart rot of pineapple ( Ananas comosus var. comosus ) on Oahu, Hawaii, along with two strains from pineapple in Malaysia, were sequenced. Orthologous average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values among the sequenced genomes ranged from 98.93 to 99.9% and 91.8 to 99.9%, respectively, supporting the classification of seven strains within the same species. Comparisons of ANI and dDDH values between these seven strains and type strains of D. zeae , D. parazeae and D. oryzae ranged from 94.4–95.9% to 57.2–66.5%, respectively. These values fall below the proposed boundaries for species designation, supporting the delineation of a novel species. Phylogenetic analyses, including 16S rRNA, gapA , multi-locus sequence analysis of ten housekeeping genes, whole genome and pangenome analyses, were concordant and revealed a distinct monophyletic clade, separating these strains from other members of the D. zeae complex, with D. oryzae as the closest relative. Notably, a nitrogen fixation gene cluster comprising 28 genes, similar to the Klebsiella spp. nitrogenase gene cluster, was found in the genome of the 7 pineapple strains. Based on polyphasic approaches, including ANI, dDDH, biochemical, physiological and phylogenomic analyses, we propose the reclassification into a new species of the five pineapple strains from Hawaii A5391, A5410 T , A5611, A6136 and A6137, together with the two pineapple strains from Malaysia CFBP 1272 and CFBP 1278, previously classified as D. zeae . We propose the name Dickeya ananatis sp. nov. for this taxon, represented by the type strain A5410 T (=ICMP 25020 T =LMG 33197 T ).

Complete genome sequences of six Serratia strains with multiple resistance genes isolated from food products in Canada

2025-06-23

Mingsong Kang , Darrell Harjadi , Emily Hoover +3 more | Microbiology Resource Announcements

Serratia species are widespread, opportunistic Gram-negative microbes found in diverse environments, with some species posing risks to humans, potentially through food. In this announcement, we present six complete genome sequences … Serratia species are widespread, opportunistic Gram-negative microbes found in diverse environments, with some species posing risks to humans, potentially through food. In this announcement, we present six complete genome sequences of two strains for each of S. liquefaciens, S. fonticola, and S. nevei, respectively, isolated from food in Canada.

Isolation and characterization of Xanthomonas campestris pv. campestris from cabbage and its Inhibition using endophytic bacteria

2025-06-23

S Preethi , S. Umesha | Vegetos

Ficha de Pararrhopalites papaveroi

2025-06-23

Douglas Zeppelini Filho , Roniere Andrade de Brito , Diego de Medeiros Bento +2 more | Datasets - Sistema SALVE - ICMBio

Nano formulation development and antibacterial activity of cinnamon bark extract-chitosan composites against Burkholderia Glumae the causative agent of Bacterial Panicle Blight in rice

2025-06-20

Qamar Mohammed-Naji , Dzarifah Zulperi , Khairulmazmi Ahmad +1 more | PLoS ONE

Bacterial panicle blight (BPB) disease, caused by Burkholderia glumae , poses a significant threat to rice production. Conventional chemical control methods contribute to environmental concerns and resistance issues, necessitating the … Bacterial panicle blight (BPB) disease, caused by Burkholderia glumae , poses a significant threat to rice production. Conventional chemical control methods contribute to environmental concerns and resistance issues, necessitating the development of sustainable alternatives. This study aimed to formulate and evaluate cinnamon bark extract-chitosan (CBE- CS) nano formulations for antibacterial efficacy against Burkholderia glumae . First, the antibacterial activity of cinnamon bark extract (CBE) was assessed, revealing a minimum inhibitory concentration (MIC) of 6.25 μg/mL and a minimum bactericidal concentration (MBC) of 12.5 μg/mL. Morphological analysis using scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), and transmission electron microscopy (TEM) showed significant bacterial cell wall damage, cytoplasmic leakage, and structural degradation after treatment. Chemical characterization of CBE using gas chromatography-mass spectrometry (GC-MS) and Fourier transform infrared spectroscopy (FTIR) identified key active compounds, with (Z)-3- phenylacryldehyde as the major component (51.24%). Next, nano formulations of CBE-CS were developed, and their physicochemical properties were characterized, including particle size, zeta potential, encapsulation efficiency (33.9%), and loading capacity (48.78%). Antibacterial assessments demonstrated that the nano formulations effectively inhibited Burkholderia. glumae . Finally, greenhouse trials on rice seedlings confirmed the efficacy of these nano formulations in controlling BPB disease, showing significant bacterial suppression and improved plant health. These findings suggest that CBE-CS nanoparticles offer a promising, eco-friendly alternative for managing bacterial blight in rice, providing both effective antibacterial activity and enhanced plant protection.

Silent Invader: Probable Phreatobacter oligotrophus Sepsis in a Preterm Neonate

2025-06-20

Aliyyah Mohammad Khuzaini , Saarah Huurieyah Wan Rosli , Nadia Yazid +1 more | Pediatric Infectious Disease

Pectobacterium sinaloense sp. nov., a novel phytopathogenic species isolated from potato plants in Mexico

2025-06-20

Jose Luis Valdez-Lopez , Noe Leonardo Palafox-Leal , Glenda Santos-Lopez +7 more | bioRxiv (Cold Spring Harbor Laboratory)

ABSTRACT As part of a broader effort to survey and characterize the diversity of pectolytic bacteria affecting potato crops in Mexico, phytopathogenic strains were isolated from soft rot symptoms in … ABSTRACT As part of a broader effort to survey and characterize the diversity of pectolytic bacteria affecting potato crops in Mexico, phytopathogenic strains were isolated from soft rot symptoms in potato plants in Sinaloa. Among them, an atypical Pectobacterium -like strain, LFLA-215 T , could not be confidently assigned to any known species through biochemical or molecular methods. To clarify its taxonomic position and explore its genomic and functional features, whole-genome sequencing and comparative analyses were conducted, accompanied by biochemical, morphological and pathogenicity evaluations. The strain LFLA-215 T is Gram-stain-negative, with peritrichous flagella, catalase-positive, and oxidase-negative. Phylogenetic analyses based on the 16S rRNA operon, dnaJ , and 923 core genes, confirmed that strain LFLA-215 T belongs to the genus Pectobacterium . However, genomic similarity values with other Pectobacterium species, ranging from 87.73–93.53% (ANIb), 87.63–93.46% (ANIu), and 34.0–52.1% (isDDH), fell below species delineation thresholds. Pectobacterium colocasium LJ1 T showed the closest relationship to LFLA-215 T , whereas Pectobacterium parmentieri RNS 08-42-1A T was the most distantly related. Although LFLA-215 T fulfilled Koch’s postulates and demonstrated pathogenicity in potato plants, its virulence on tubers was comparatively lower than that of other known Pectobacterium strains, which could be related to the size and the reduction of the total number of genes when analyzed its complete genome reported here. Taken all together, our findings support the classification of strain LFLA-215 T as a novel species within the genus Pectobacterium , for which the name Pectobacterium sinaloense sp. nov. is proposed, with LFLA-215 T designated as the type strain.

The Fusion Gene BPI-LY, Encoding Human Bactericidal/Permeability-Increasing Protein Core Fragments and Lysozyme, Enhanced the Resistance of Transgenic Tomato Plants to Bacterial Wilt

2025-06-20

Lei Ni , Yue Zhang , Yafei Qin +7 more | Plants

Tomato bacterial wilt, caused by Ralstonia solanacearum (G−), is one of the most devastating plant diseases. Developing effective resistance against this pathogen remains a major challenge in plant disease management. … Tomato bacterial wilt, caused by Ralstonia solanacearum (G−), is one of the most devastating plant diseases. Developing effective resistance against this pathogen remains a major challenge in plant disease management. In this study, we constructed a fusion gene BPI-LY by combining the gene encoding the lipophilic functional domains of human bactericidal/permeability-increasing protein (BPI) with the gene of human lysozyme (LY). The recombinant gene BPI-LY was heterologously expressed in yeast and tomato. Preliminary in vitro assays in yeast demonstrated that BPI enhances LY’s antibacterial activity against G− bacteria. Furthermore, overexpression of BPI-LY in tomato delayed onset of the disease in the transgenic lines and lowered the degree of tissue damage and the number of bacteria present in the stems relative to those in the wild-type plant. Additionally, the expression levels of the SlSOD, SlPOD, SlPAL, SlPR5, SlPR10, and SlPR-NP24 genes were indirectly upregulated in the transgenic plants following R. solanacearum inoculation. Collectively, these findings demonstrate that BPI-LY enhances the resistance of transgenic tomato against bacterial wilt caused by R. solanacearum.

First report of Microdochium sp. causing leaf blight on garlic (Allium sativum L.) in India

2025-06-19

J. S. Remya , Jalaja S. Menon , M. Nafeesa +4 more | Journal of Mycopathological research

A simple and convenient method for antimicrobial susceptibility testing of plant pathogenic bacteria

2025-06-18

Mizue Tsuji , Takashi Fujikawa , Yasuhiro Inoue +1 more | Journal of General Plant Pathology

Molecular-Marker-Based Design for Breeding Indica–Japonica Hybrid Rice with Bacterial Blight Resistance

2025-06-18

Junjie Dong , Xinyue Zhang , Youfa Li +1 more | Genes

Background/Objectives: To overcome the limitations imposed by bacterial blight on widely adopted indica-japonica hybrid rice, this study employed molecular design breeding strategies to develop a resistant germplasm. Methods: Through conventional … Background/Objectives: To overcome the limitations imposed by bacterial blight on widely adopted indica-japonica hybrid rice, this study employed molecular design breeding strategies to develop a resistant germplasm. Methods: Through conventional backcross breeding combined with molecular-marker-assisted selection, the Xa23-carrying material XR39 was hybridized with the wide-compatibility restorer line R5315 harboring the S5n gene. Progeny selection integrated evaluations of agronomic traits, disease resistance identification, and test-crossing with sterile lines. Results: Five wide-compatibility restorer lines simultaneously incorporating the Xa23 and S5n genes were successfully developed, demonstrating outstanding bacterial blight resistance and restoration ability. The selected hybrid combinations, A3/RP1, A1/RP4, and A4/RP4, exhibited yield increases of 2.6-8.6% compared to the control. Conclusions: This study not only established a novel germplasm for developing bacterial blight-resistant indica-japonica hybrid rice varieties, but also established a model for gene design breeding for rice improvement.

Complete and nearly complete genome sequences of seven strains of Burkholderia glumae and B. gladioli isolated from rice panicles in Vietnam

2025-06-18

Đoàn Thị Kiều Tiên , Văn Quốc Giang , Pham Van Luc +5 more | Microbiology Resource Announcements

ABSTRACT Burkholderia gladioli and Burkholderia glumae are two of the main pathogens associated with bacterial panicle blight, a major disease of rice worldwide. Here, we present complete and nearly complete … ABSTRACT Burkholderia gladioli and Burkholderia glumae are two of the main pathogens associated with bacterial panicle blight, a major disease of rice worldwide. Here, we present complete and nearly complete genome assemblies of three B. glumae and four B. gladioli strains isolated from rice collected in the Mekong Delta area.

An Ethylicin Dosage Form - for Bacterial Wilt Disease Control

2025-06-17

Lei Yang , Dong Xiang , Guan Lin +4 more | Journal of Plant Biology

Tomato Bacterial Speck and Leaf Blight in Iran Caused by Two Members of the Pseudomonas syringae Complex

2025-06-17

Habibeh Hajian‐Maleki , Asma Rahmanzadeh , Masoud Shams‐Bakhsh +1 more | Plant Pathology

ABSTRACT Seed‐borne bacterial diseases caused by taxonomically diverse pathogens are economically important constraints threatening the tomato ( Solanum lycopersicum ) industry in both open‐field and greenhouse productions globally. While Xanthomonas … ABSTRACT Seed‐borne bacterial diseases caused by taxonomically diverse pathogens are economically important constraints threatening the tomato ( Solanum lycopersicum ) industry in both open‐field and greenhouse productions globally. While Xanthomonas euvesicatoria and Clavibacter michiganensis causing bacterial spot and bacterial canker diseases, respectively, are prevalent bacterial diseases of tomato, pathogenic members of the Pseudomonas syringae species complex occasionally play an important role in tomato health and productivity. Within the past few years, nationwide comprehensive field surveys and samplings were conducted in tomato‐producing areas in Iran to monitor the status of bacterial diseases of the crop in the country. Besides plenty of Xanthomonas and Clavibacter spp., nine gram‐negative, cream‐coloured bacterial strains were isolated from symptomatic tomato plants showing leaf speck and pith necrosis. The latter strains were identified as members of the P. syringae species complex based on phenotypic features, for example, colony morphology, pigmentation and LOPAT scheme. Precise phylogenetic position and taxonomic status of the strains were determined using the phylogeny of gyrB and rpoD gene sequences. Accordingly, three strains were identified as Pseudomonas viridiflava , while six strains were clustered in a monophyletic clade next to the pathotype strains of P. syringae pv. maculicola and P. syringae pv. apii within the phylogroup 01a of P. syringae sensu lato. All strains induced symptoms on tomato plants under greenhouse conditions resembling those observed in the field. Results of the present study highlight the probability of establishing P. syringae infection on tomato crops in Iran despite being less prevalent under natural conditions.

Molecular characterization and exploration of streptomycin resistance genes in Xanthomonas campestris pv. campestris isolates from diverse agro climatic regions of Karnataka state, southern India

2025-06-17

Beluvigi Lingaraj , T. S. Murali , K. Ajithkumar +4 more | European Journal of Plant Pathology

The NLR immune receptor Roq1 recognizes thePseudomonas syringaeHopAG1 effector via its Nudix domain

2025-06-17

Magdalena Górecka , Martyna Jonak , Marta Grech‐Baran +6 more | bioRxiv (Cold Spring Harbor Laboratory)

Plant nucleotide-binding leucine-rich repeat receptors (NLRs) sense directly or indirectly effectors - proteins employed by pathogens during infection. While indirect recognition can be initiated by unrelated effectors targeting the same … Plant nucleotide-binding leucine-rich repeat receptors (NLRs) sense directly or indirectly effectors - proteins employed by pathogens during infection. While indirect recognition can be initiated by unrelated effectors targeting the same cellular component, direct recognition is restricted by conformational constraints of the pathogen protein and corresponding receptor. Recognition of XopQ (Roq1) receptor confers resistance to bacteria expressing members of the highly conserved effector family comprising XopQ/HopQ1/RipB. The structure of the activated Roq1 was solved previously, revealing that LRR and C-JID domains of Roq1 are involved in XopQ binding. In this study, we found that Roq1 detects HopAG1, a member of a structurally different effector family. Presence of HopAG1 in Pseudomonas syringae reduced bacterial growth and symptoms development in wild-type but not in roq1 Nicotiana benthamiana plants. Moreover, HopAG1 co-immunoprecipitated with Roq1 indicating that both proteins associate. Based on deletion and structural analyses, we postulate that this interaction occurs via the Nudix domain of HopAG1 that binds to a similar receptor interface like XopQ. Nudix fold is predicted in multiple pathogen effectors suggesting that Roq1 may recognize effector families other than XopQ and HopAG1. Accordingly, it is also conceivable that other TNLs may detect a broader range of effector families than supposed.

Unified Classification of the Type III Secreted Effectors of Bacterial Plant Pathogens to Advance Phytopathology Research

2025-06-17

David Tsz Chung Chan , Viplav Agarwal , David A. Baltrus +1 more | Phytopathology

Many diverse bacterial phytopathogens deploy type III secreted effectors (T3SEs) to promote virulence by interrupting host immunity and other critical plant processes. However, the virulence of T3SEs has been countered … Many diverse bacterial phytopathogens deploy type III secreted effectors (T3SEs) to promote virulence by interrupting host immunity and other critical plant processes. However, the virulence of T3SEs has been countered on the host side through the evolution of a multitude of resistance genes (R-genes) capable of recognizing the presence of T3SEs and eliciting a response termed effector triggered immunity (ETI). This dynamic sets up an evolutionary arms race that has led to enormous diversification of both bacterial T3SEs and plant R-genes. Over the past decade, efforts to document and characterize the pangenome T3SE profiles of individual pathogens have generated indispensable resources that have facilitated collaborative research progress on these focal pathogens. However, despite the deeply integrated evolutionary history of T3SEs, the lack of concerted effort to synthesize T3SE conventions across diverse pathosystems has resulted in a lack of connectivity across the literature. Here, we catalogue the distribution of T3SEs across six of the most globally significant genera of bacterial phytopathogens. We show that the number of T3SEs per genome varies dramatically within and between genera, and that many T3SE families are present in multiple genera despite their sparse distributions across closely related strains. We also document all inter-genera evolutionary relationships for each T3SE family and propose integrated nomenclature conventions for all phytopathogen T3SEs. Ultimately, our expanded T3SE collection includes thousands of newly classified alleles, catalogues several previously unestablished homologies between distinct genera, and will enable more comprehensive studies on the implications of T3SE diversification for virulence and immunity.

Complete genome sequence of Xanthomonas euvesicatoria pv. polysciadis pathotype strain Pgu1 PT , a phytopathogenic bacterium isolated from Polyscias guilfoylei (geranium aralia)

2025-06-17

Chien-Fu Wu , Shin Lee , Yi-Chiao Huang +1 more | Microbiology Resource Announcements

ABSTRACT Here, we report the complete genome sequence of Xanthomonas euvesicatoria pv. polysciadis strain Pgu1 PT , a phytopathogenic bacterium causing necrotic leaf lesions on Polyscias guilfoylei in Taiwan. The … ABSTRACT Here, we report the complete genome sequence of Xanthomonas euvesicatoria pv. polysciadis strain Pgu1 PT , a phytopathogenic bacterium causing necrotic leaf lesions on Polyscias guilfoylei in Taiwan. The genome consists of a 5,129,423 bp circular chromosome (GC content: 64.8%) and a 53,818 bp circular plasmid (GC content: 62.1%).

Development of oil-in-water emulsion formulation of Clavibacter michiganensis subsp. michiganensis specific bacteriophage and biocontrol efficacy

2025-06-17

Duygu Bekircan Eski , Ardahan Eski , Cihan Darcan | Phytoparasitica

Monitoring the Occurrence and Distribution of Stewart’s Wilt of Maize in Iran

2025-06-17

Hosna Alvandi , Seied Mohsen Taghavi , Sadegh Zarei +6 more | Plant Disease

Stewart’s wilt of maize caused by the Gram-negative bacterium Pantoea stewartii subsp. stewartii is one of economically important diseases of the crop around the globe. The disease has not yet … Stewart’s wilt of maize caused by the Gram-negative bacterium Pantoea stewartii subsp. stewartii is one of economically important diseases of the crop around the globe. The disease has not yet been reported in Iran. Following preliminary observation of suspected symptoms on maize plants in Southeastern Iran in 2019, a four-year comprehensive field survey and sampling program was initiated across maize growing areas in the country to monitor the occurrence and distribution of the disease. During 2019-2022, 180 maize fields were surveyed from which 400 symptomatic and asymptomatic maize samples were collected. Among dozens of bacterial strains isolated from leaves and stems of maize plants, 22 strains phenotypically resembled those of Pantoea spp. Species-specific PCR and multilocus phylogenetic analyses using the sequences of atpD, gyrB, infB, and rpoB genes showed that P. stewartii subsp. stewartii is the causal agent of Stewart’s wilt in Iran. All strains induced leaf chlorosis and plant stunting on maize plants under greenhouse conditions 7-15 days post inoculation; confirmed with accomplishment of Koch's postulates. These 22 strains were isolated in Bushehr, Fars, Hormozgan, Kermanshah, Khuzestan, Kohgiluyeh-Boyer Ahmad, and Sistan-Baluchistan provinces. Results of the present study confirmed the occurrence of P. stewartii subsp. stewartii causing Stewart’s wilt of maize in Iran. Occurrence of Stewart’s wilt on maize in Iran can lead to yield reduction, trade restrictions, increased control costs, and threats to food security. Considering quarantine status of the pathogen in Iran, strict inspections are warranted to combat potential threats due to Stewart’s wilt epidemics in the country.

The TALE Effector PthA4 of Xanthomonas citri subsp. citri Indirectly Activates an Expansin Gene CsEXP2 and an Endoglucanase CsEG1 via CsLOB1 to Cause Citrus Canker Symptoms

2025-06-16

Rikky Rai , Nian Wang | Molecular Plant-Microbe Interactions

Citrus canker caused by Xanthomonas citri subsp. citri (Xcc) is an important citrus disease worldwide. PthA4 is the most important pathogenicity gene of Xcc and encodes a transcription activator like … Citrus canker caused by Xanthomonas citri subsp. citri (Xcc) is an important citrus disease worldwide. PthA4 is the most important pathogenicity gene of Xcc and encodes a transcription activator like effector (TALE) secreted by the type III secretion system. PthA4 is known to activate the expression of CsLOB1, the canker susceptibility gene and a transcription factor, to cause citrus canker symptoms. Extensive effort was made to identify downstream targets of CsLOB1 to investigate the mechanism underlying canker symptom development. However, none of identified CsLOB1 target genes have been confirmed to be involved in citrus canker development. Here, we first identified the direct targets of CsLOB1 by generating promoter-uidA (GUS) reporter fusion construct for the 13 genes highly induced by both PthA4 and CsLOB1 and monitored the reporter activity in N. benthamiana leaves co-expressing CsLOB1. Agrobacterium tumefaciens-mediated transient expression of CsLOB1 activated seven gene promoters in N. benthamiana including Cs7g18460, Orange1.1t00600, Cs6g17190, Cs7g32410 (CsEXP2), Cs2g27100, Cs2g20750 (CsEG1), and Cs9g17380. Next, we constructed dTALEs to target unique sequences in the promoters of the seven direct target genes of CsLOB1 and transformed them into XccpthA4::Tn5 mutant. Our results indicate that a combination of 5 and 7 dTALEs caused canker-like symptoms in the inoculated citrus leaves. In addition, dTALECsEXP2 and dTALECsEG1 caused water soaking and pustules, which are typical canker symptoms. Taken together, Xcc indirectly activates CsEXP2 and CsEG1 via PthA4-CsLOB1 to cause canker symptoms. Identification of direct targets of CsLOB1 provides alternative targets for genetic improvement of citrus against canker via genome editing.

The complete genome of Xanthomonas citri pv. mangiferaeindicae strain B3, isolated from diseased mango leaves in Guangxi, China

2025-06-16

Qiufei Ouyang , Cuifeng Yang , Lingling Lv +3 more | Microbiology Resource Announcements

ABSTRACT In this study, we sequenced the complete genome of Xanthomonas citri pv. mangiferaeindicae strain B3, isolated from mango leaves with black spot symptoms. The 5.29 Mb genome comprises one … ABSTRACT In this study, we sequenced the complete genome of Xanthomonas citri pv. mangiferaeindicae strain B3, isolated from mango leaves with black spot symptoms. The 5.29 Mb genome comprises one circular chromosome and two plasmids, with a GC content of 64.5%, shedding light on its virulence and antibiotic resistance mechanisms.

Pathogen-Informed Strategies for Durable Resistance in Rice: Lessons from Bacterial Blight

2025-06-16

Jagjeet Singh Lore , Dale Pinili , Dharminder Bhatia +7 more | Annual Review of Phytopathology

Bacterial blight (BB), caused by Xanthomonas oryzae pathovar oryzae ( Xoo ), is a major rice disease in Asia and Africa. Xoo possesses virulence factors for pathogenicity and race differentiation … Bacterial blight (BB), caused by Xanthomonas oryzae pathovar oryzae ( Xoo ), is a major rice disease in Asia and Africa. Xoo possesses virulence factors for pathogenicity and race differentiation that complicate resistance breeding of rice. The availability of 48 BB resistance ( R ) genes ( Xa/xa ) portends the selection of R genes for broad and durable resistance. To establish durable resistance, understanding the pathogen virulence spectrum and host resistance mechanisms is required. This review examines the global distribution and diversity of Xoo populations, highlights the different resistance mechanisms of 15 Xa/xa genes, and identifies the three effective resistance genes for 24 countries. The review proposes strategies for durable, broad-spectrum resistance to BB.

Characterizing the structural variations in the genome of the mandarin variety, <scp>IrM2</scp>, induced by gamma irradiation

2025-06-15

Upuli Nakandala , Agnelo Furtado , Ardashir Kharabian Masouleh +3 more | Plant Biotechnology Journal

Fruits with few or no seeds are favoured by consumers because they provide an improved eating experience alongside other important quality traits such as taste and shelf-life. Gamma irradiation has … Fruits with few or no seeds are favoured by consumers because they provide an improved eating experience alongside other important quality traits such as taste and shelf-life. Gamma irradiation has been widely used to induce favourable trait changes in plants, including a reduction in seediness. For this reason, it has been extremely important in the development of new commercial citrus cultivars. The variety IrM2 is a mutant derived from the mandarin variety, Murcott, by gamma irradiation. IrM2 has improved consumer and economic appeal due to its earlier fruit maturity time, low number of seeds and improved external skin colour compared with its progenitor. Here, we developed high-quality, haplotype-resolved genomes for Murcott and IrM2, using PacBio HiFi and Hi-C sequencing. The assemblies ranged from 329 to 344 Mb, with N50s of more than 30 Mb, and more than 98% assembly and annotation completeness for the four haplotypes. Duplications, inversions, translocations and INDELs were the predominant types of mutations found in IrM2. Two large heterozygous inversions (3.1 Mb in Chr3 and 8.6 Mb in Chr6) and one large heterozygous, non-reciprocal translocation (between Chr3 and Chr6) were prominent in IrM2 and may be the causes of the reduced seeds. Variations such as insertions and deletions were also found, resulting in additions and loss of genes in IrM2. The genes lost in IrM2 were associated with many processes, including hormone signalling, flowering, DNA transcription, reproduction, gene expression and transmembrane transport. These high-quality genomes contribute to a deeper understanding of how irradiation affects plant genomes.

Droplet Digital PCR for the Detection of Pseudomonas savastanoi pv. savastanoi in Asymptomatic Olive Plant Material

2025-06-14

Giuseppe Tatulli , Nicoletta Pucci , Elena Santilli +2 more | Plants

Olive knot disease, caused by Pseudomonas savastanoi pv. savastanoi, severely impacts olive tree yield and oil quality. Early and accurate detection of the bacterium’s presence, particularly in asymptomatic plants, is … Olive knot disease, caused by Pseudomonas savastanoi pv. savastanoi, severely impacts olive tree yield and oil quality. Early and accurate detection of the bacterium’s presence, particularly in asymptomatic plants, is crucial for effective disease management. This study aimed to develop an improved protocol for processing plant samples and adapting quantitative PCR to droplet digital PCR (ddPCR). For this purpose, four plant preparations—EW (external washing), PELLET (bacterial concentration), and enrichment in liquid media for 24 or 48 h (24hE, 48hE)—were tested using spiked samples. The ddPCR was set up and compared with qPCR to evaluate analytical sensitivity and specificity. Additionally, field samples from symptomatic and asymptomatic olive orchards were tested to evaluate the performance of the selected methods in naturally infected plants. ddPCR showed higher sensitivity than qPCR, particularly with the PELLET and 24hE preparations. The PELLET from the spiked sample preparation achieved a limit of detection of 10 CFU/mL for both molecular tests. The ddPCR, combined with the PELLET preparation, offers a highly sensitive and reliable tool for detecting P. savastanoi pv. savastanoi in asymptomatic olive material. This protocol shows great potential for improving early bacterial detection and disease prevention, thus aiding control strategies in nurseries and olive orchards, and supporting the production of certified plant propagation material.

Climate-Driven Insights: Predicting Black Pepper Yield and Quality with Long Short-term Memory Model

2025-06-13

H. M. P. A. Subasinghe , K. A. S. H. Kulathilake | International Journal on Advances in ICT for Emerging Regions (ICTer)

In the context of climate variability, predicting agricultural output remains a pressing challenge, particularly for high-value crops like black pepper in Sri Lanka, a leading spice exporter. This study introduces … In the context of climate variability, predicting agricultural output remains a pressing challenge, particularly for high-value crops like black pepper in Sri Lanka, a leading spice exporter. This study introduces a novel machine-learning approach to predict black pepper yield and quality, utilizing thirty years of detailed weather data from the Matale district. Employing Long Short-Term Memory (LSTM) networks, the complex dependencies between weather conditions—including rainfall, temperature, and humidity—and crop productivity are modelled. The analysis demonstrates that LSTM models can effectively forecast black pepper yield and quality by learning from historical weather patterns and corresponding crop performance data. The models achieved a mean absolute error of 18-20% for quality predictions and a mean squared error reflecting consistent model performance across different evaluations. By providing reliable yield and quality estimates, these models serve as valuable tools for farmers and policymakers to better plan and manage black pepper cultivation in response to anticipated climate conditions. Furthermore, the research highlights the potential for enhancing model accuracy by incorporating diverse regional data, thereby contributing to more resilient agricultural practices in the face of global climate change.

An Emerging Bacterial Leaf Disease in Rice Caused by Pantoea ananatis and Pantoea eucalypti in Northeast China

2025-06-13

Guohua Duan , Xin Liu , Shaoqi Zhang +5 more | Microorganisms

Rice production faces new challenges from emerging diseases due to intensive cultivation practices and climate warming in China. A new rice leaf bacterial disease has recently occurred in Northeast China. … Rice production faces new challenges from emerging diseases due to intensive cultivation practices and climate warming in China. A new rice leaf bacterial disease has recently occurred in Northeast China. The symptoms of the disease are similar to those of bacterial leaf blight. Disease lesions spread along leaf edges and are later dried up due to water loss. In this study, 17 bacterial isolates were identified as the causal agents of the new disease following Koch’s postulates. These strains are categorized into two groups based on colony morphology and molecular characterization. Phylogenetic analysis using the five housekeeping genes leuS, gyrB, fusA, pyrG, and rplB reveals that the two groups of the isolates belong to Pantoea ananatis and P. eucalypti, respectively. The new rice disease is caused by P. ananatis, P. eucalypti, or a combination of both bacterial species. A complete genome map has also been assembled for P. eucalypti. Meanwhile, some important virulence factors have been predicted based on gene annotation and determination of extracellular enzymes. Collectively, this study represents the first report of a new rice leaf disease caused by P. eucalypti and the first high-quality genome assembly of P. eucalypti that infects rice leaves.

Effects of the vfm quorum-sensing system on the phenotypic features and virulence of Dickeya zeae WH1

2025-06-13

Xiaojuan Tan , Yang Ting , Mengyin Wu +5 more | Biofilm

A critical role of sux cistron-mediated sucrose uptake for virulence of the rice blight pathogen Xanthomonas oryzae pv. oryzae

2025-06-12

Nora R. Zöllner , Juying Long , Congfeng Song +7 more | bioRxiv (Cold Spring Harbor Laboratory)

Abstract The virulence of Xanthomonas oryzae pv. oryzae , the causal agent of bacterial blight (BB) of rice, critically depends on the activation of SWEET sucrose uniporters of the host. … Abstract The virulence of Xanthomonas oryzae pv. oryzae , the causal agent of bacterial blight (BB) of rice, critically depends on the activation of SWEET sucrose uniporters of the host. To date, the role of SWEET-released sucrose for virulence remains unclear. We here identified the sux locus of Xoo , consisting of a LacI-type repressor (SuxR), an outer membrane TonB-like porin (SuxA), an inner membrane MFS H + -symporter (SuxC), and a cytosolic sucrose hydrolase (SuxB). Structural and functional analyses demonstrate that SuxB has exclusive sucrose hydrolase activity. Mutant analyses show that the transporter SuxC and the sucrose hydrolase are necessary for growth of bacteria on sucrose, while SuxA is not essential, likely due to the ability of other porins to transport sucrose across the outer membrane. Consistent with a role of SuxR as a sucrose repressor, transcriptome studies show sucrose-dependent regulation of the suxA/suxB genes. Besides a role of sucrose for reproduction, we found that sucrose promotes motility, EPS production, biofilm formation, and virulence. Notably, the SuxC sucrose H + -symporter and the sucrose hydrolase SuxB were required for full virulence of Xoo on indica and japonica rice varieties. Our findings indicate that pathogen-induced sucrose efflux via SWEETs provides sucrose to Xoo , that Xoo uses the sux gene cluster to acquire and utilize sucrose, and that sucrose promotes bacterial fitness and xylem colonization. Significance Statement Understanding disease mechanisms is critical for developing strategies to protect plants against infections. Bacterial blight, a major threat to global rice production, is caused by Xanthomonas oryzae pv. oryzae strains that hijack rice SWEET sucrose uniporters. Xanthomonas oryzae pv. oryzae deploys a set of molecular “keys”, TAL effectors, to trigger host sucrose release. Sugars could serve as nutrients for the bacteria or prime host defense. Here, we provide evidence that the pathogen’s ability to attack and grow depends on sucrose uptake. We explore how crucial virulence functions, such as motility, EPS production, and biofilm formation, depend on the activity of the sucrose utilization system, supporting a key role of sucrose for the nutrition of the bacteria in the xylem.

Ralstonia pseudosolanacearumLOV domain protein regulates environmental stress tolerance, iron homeostasis, and bacterial wilt virulence

2025-06-12

Bridget S. O’Banion , Mariama D. Carter , Juan Gallego +5 more | bioRxiv (Cold Spring Harbor Laboratory)

Abstract Bacteria use diverse sensors to integrate environmental stimuli into physiological responses that ensure fitness and survival. Ralstonia pseudosolanacearum ( Rps ), a soil-borne plant pathogen that causes bacterial wilt … Abstract Bacteria use diverse sensors to integrate environmental stimuli into physiological responses that ensure fitness and survival. Ralstonia pseudosolanacearum ( Rps ), a soil-borne plant pathogen that causes bacterial wilt disease, encodes a conserved LOV (light-oxygen-voltage) protein that mediates photoreception across the tree of life. However, Rps had a minimal LOV-dependent transcriptional response to light in culture. Clues from functional domains, the lov genomic neighborhood, and transcriptional analyses suggest that LOV shapes Rps biology in response to stress. Loss of LOV did not affect Rps biofilm or motility in vitro , but did influence expression of genes encoding for these phenotypes in planta . The Δlov mutant had reduced heat tolerance and broad metabolic dysregulation, leading to growth defects on several carbon sources but a growth advantage in ex vivo tomato xylem sap and in high-iron medium. In vitro , the Δlov mutant was more tolerant than wild type of redox stress and the antimicrobial phenolic caffeate, but Rps required lov for full virulence on tomato. LOV mediated attachment to the root surface, stem colonization, and overall symptom development. Together these findings reveal that LOV, which is highly conserved among plant pathogenic Ralstonia , modulates Rps stress response and virulence independently of light cues, but in a plant-dependent fashion. Importance Like other plant-associated microbes, the destructive crop pathogen Ralstonia pseudosolanacearum ( Rps ) must integrate a complex array of biotic and abiotic signals to successfully infect and colonize the roots and xylem vessels of its plant hosts. Rps encodes a large LOV domain protein. LOV proteins sense blue light in leaf colonizing microbes, but Rps inhabits soil, plant roots, and xylem where there is little blue light. Although deleting lov had only minor effects when the bacterium grew in culture, many genes were dysregulated when the Δlov mutant infected tomato plants. Functional experiments showed LOV has diverse light-independent roles in Rps , including modulating environmental stress tolerance and cellular iron and redox status. Most importantly, Rps needs LOV to grow normally in plants and cause bacterial wilt disease. Thus, LOV is a key sensor-regulator that controls Rps adaptation to the plant environment and virulence.

High-quality draft genome sequences of Pseudomonas guariconensis ABJ_B2_1 and Pseudomonas shirazica ABJ_A22_2_1

2025-06-12

Ahmed Olowo‐okere , Evelyn Skiebe , Gottfried Wilharm | Microbiology Resource Announcements

ABSTRACT We report the draft genome sequences of Pseudomonas guariconensis ABJ_B2_1 and Pseudomonas shirazica ABJ_A22_2_1, isolated from soil in Gwagwalada, Nigeria. The genomes were 4.98 Mb (40 contigs) and 5.71 … ABSTRACT We report the draft genome sequences of Pseudomonas guariconensis ABJ_B2_1 and Pseudomonas shirazica ABJ_A22_2_1, isolated from soil in Gwagwalada, Nigeria. The genomes were 4.98 Mb (40 contigs) and 5.71 Mb (112 contigs) in size, with GC contents of 62.68% and 62.63%, respectively.

Tailocin Tail Fiber Diversity Correlates with rfbD Variation in the Pseudomonas syringae Species Complex

2025-06-12

Chad Fautt , Kevin L. Hockett , Sandrine Delattre +2 more | ISME Communications

Abstract Community assembly dynamics are in part driven by competition between community members. Diverse bacteria can antagonize competitors through the production of toxic compounds, such as bacteriophage-derived tailocins. These toxins … Abstract Community assembly dynamics are in part driven by competition between community members. Diverse bacteria can antagonize competitors through the production of toxic compounds, such as bacteriophage-derived tailocins. These toxins are highly specific in their targeting, which is determined by interactions between the tailocin’s tail fiber and competitors’ lipopolysaccharide O-antigen moieties. Tailocins play a pivotal role in mediating microbial interactions among the economically significant plant pathogens within the Pseudomonas syringae species complex, with the potential to alter community structure and disease progression in host plants. Previous work looking at 45 P. syringae strains has demonstrated that at least two phylogenetic clades of tail fibers are encoded in the conserved tailocin region across the species complex, which roughly corresponds to two clusters of targeting activity. To better understand the full diversity of tail fibers associated with tailocins in the species complex, we screened 2161 publicly available genomes for their tailocin tail fiber content, predicted protein structures that represent the diversity of fibers, and investigated forces possibly driving the distribution of fibers throughout the species complex. Here we present evidence that, while the two previously described tail fiber clades are indeed widespread among virulent P. syringae strains, their distribution displays low congruency with with phylogeny. Instead, we found that the presence of one tail fiber or the other is strongly correlated with the allelic diversity of another gene, associated with lipopolysaccharide O-antigen structure, dTDP-4-dehydrorhamnose reductase. Our findings suggest the presence of two reciprocally targeting groups of strains distributed throughout the P. syringae species complex that transcend phylogenetic relationships.

Reclassification and Pathogenesis of Clavibacter Species: A Model Pathogen for Studying the Molecular Interactions Between Gram-Positive Bacteria and Plants

2025-06-12

In Woong Park , Eom‐Ji Oh , In Sun Hwang +1 more | Phytopathology

Phytopathogenic bacteria of the genus Clavibacter cause severe yield loss, resulting in significant economic damage to various commercial crops worldwide. These bacteria pose a significant risk to global crop productivity … Phytopathogenic bacteria of the genus Clavibacter cause severe yield loss, resulting in significant economic damage to various commercial crops worldwide. These bacteria pose a significant risk to global crop productivity due to their high transmissibility and the challenges of early detection. Although Clavibacter bacteria are important pathogens in agriculture, there is limited understanding of their virulence factors and their interactions with host plants. To provide a thorough understanding of the genus, we present the specific features of eight Clavibacter species, including their reclassification based on comparative genomic information, disease cycles, and virulence factors reported to date, including CAZymes, serine proteases, transcriptional regulators, and additional factors. Based on the reported virulence genes of C. michiganensis and C. capsici, the causal agents of bacterial canker in tomato and pepper respectively, we briefly propose an overview of the molecular interactions between these pathogens and plants. Overall, we hope that this review will broaden our understanding of the pathogenesis of Clavibacter and provide new perspectives on the relationships between Gram-positive phytopathogenic bacteria and their host plants.