Plant disease resistance genes function in highly specific pathogen recognition pathways. RPS2 is a gene of Arabidopsis thaliana that confers against Pseudomonas syringae bacteria express avirulence avrRpt2 . was isolated by the use positional cloning strategy. The derived amino acid sequence contains leucine-rich repeat, membrane-spanning, leucine zipper, and P loop domains. product defense signal transduction postulated to involve nucleotide triphosphate binding protein-protein...

Using physical and genetic data, we have demonstrated that Rhizobium meliloti SU47 has a symbiotic megaplasmid, pRmeSU47b, in addition to the previously described nod-nif megaplasmid pRmeSU47a. This plasmid includes four loci involved exopolysaccharide (exo) synthesis as well two thiamine biosynthesis. Mutations at exo been shown result formation of nodules which lack infection threads (Inf-) fail fix nitrogen (Fix-). Thus, both megaplasmids contain genes nitrogen-fixing root nodules. other...

The Pseudomonas syringae type III effector AvrRpt2 promotes bacterial virulence on Arabidopsis thaliana plants lacking a functional RPS2 gene (rps2 mutant plants). To investigate the mechanisms underlying activity of AvrRpt2, we examined phenotypes transgenic A. rps2 seedlings constitutively expressing AvrRpt2. These exhibited reminiscent mutants with altered auxin physiology, including longer primary roots, increased number lateral and sensitivity to exogenous auxin. They also had levels...

SUMMARY Successful pathogen infection likely involves the suppression of general antimicrobial host defences. One Pseudomonas syringae virulence factor proposed to act in this manner is coronatine (COR), a phytotoxin believed function as an analogue one or more jasmonates, family plant growth regulators. COR biosynthetic (COR(-)) mutants P. pv. tomato strain DC3000 exhibit reduced on Arabidopsis thaliana and tomato. In present study, three genetically biochemically defined COR(-) were used...

Summary A new allele of the coronatine‐insensitive locus ( COI1 ) was isolated in a screen for Arabidopsis thaliana mutants with enhanced resistance to bacterial pathogen Pseudomonas syringae . This mutant, designated coi1‐20 , exhibits robust several P. isolates but remains susceptible virulent pathogens Erisyphe and cauliflower mosaic virus. Resistance strain Pst DC3000 plants is correlated hyperactivation PR‐1 expression accumulation elevated levels salicylic acid (SA) following...

A molecular genetic approach was used to identify and characterize plant genes that control bacterial disease resistance in Arabidopsis. screen for mutants with altered the pathogen Pseudomonas syringae pv. tomato (Pst) expressing avirulence gene avrRpt2 resulted isolation of four susceptible rps (resistance P. syringae) mutants. The lost specifically strains as they retained Pst avrB or avrRpm1. Genetic analysis indicated each mutants, susceptibility due a single mutation mapping same locus...

Differential gene expression in the mother cell chamber of sporulating cells Bacillus subtilis is determined part by an RNA polymerase sigma factor called σ K (or 27 ). The was assigned as product sporulation spoIVCB on basis partial amino-terminal amino acid sequence purified protein. now shown to be a truncated capable specifying only terminal half . carboxyl specified another gene, spoIIIC , which becomes joined inframe at intermediate stage site-specific recombination within 5-base pair...

Plant pathogen resistance is mediated by a large repertoire of ( R ) genes, which are often clustered in the genome and show high degree genetic variation. Here, we that an Arabidopsis thaliana -gene cluster also subject to epigenetic We describe heritable but metastable variant bal overexpresses -like gene At4g16890 from on Chromosome 4. The transgenics overexpressing dwarfed constitutively activate salicylic acid (SA)-dependent defense response pathway. Overexpression related occurs ssi1 s...

Many plant pathogens suppress antimicrobial defenses using virulence factors that modulate endogenous host defenses. The Pseudomonas syringae phytotoxin coronatine (COR) is believed to promote by acting as a jasmonate analog, because COR-insensitive 1 (coi1) Arabidopsis thaliana and tomato mutants are impaired in signaling exhibit reduced susceptibility P. syringae. To further investigate the role of disease development, we analyzed several jasmonate-insensitive A. for pv. strain DC3000...

The roles of the phytotoxin coronatine (COR) and salicylic acid (SA)-mediated defenses in interaction Pseudomonas syringae pv. tomato DC3000 (Solanum lycopersicum) were investigated. Unlike findings reported for Arabidopsis thaliana, mutants impaired production COR or one its components, coronafacic (CFA) coronamic (CMA), induced distinctly different disease lesion phenotypes tomato. Tomato plants inoculated with CFA- CMA- mutant DB29 showed elevated transcript levels SlICS, which encodes...

To identify Pseudomonas syringae pv. tomato genes involved in pathogenesis, we carried out a screen for Tn5 mutants of P. DC3000 with reduced virulence on Arabidopsis thaliana. Several defining both known and novel loci were identified. Six contained insertions biosynthetic the phytotoxin coronatine (COR). The COR are chromosomally encoded arranged two separate clusters, which encode enzymes responsible synthesis coronafacic acid (CFA) or coronamic (CMA), defined intermediates biosynthesis....

The avrRpt2 locus from Pseudomonas syringae pv. tomato causes virulent strains of P. to be avirulent on some, but not all, lines Arabidopsis thaliana and Glycine max (soybean). We determined the DNA sequence identified gene as a 768-bp open reading frame encoding putative 28.2-kDa protein. Deletion analysis transcription studies provided further evidence that this encodes AvrRpt2. found also has avirulence activity in pathogens Phaseolus vulgaris (common bean), suggesting disease resistance...

During sporulation in Bacillus subtilis , expression of developmental genes spoIVCB and cotD is induced the mother cell compartment sporangium at morphological stages IV V, respectively. A 27-kilodalton RNA polymerase sigma factor called σ K (or 27 ) has been found that causes weak transcription strong . 14-kD protein was also discovered changes specificity -containing polymerase, greatly stimulating markedly repressing transcription. Both are products known to be required for specific cell....

Phytopathogenic bacteria possess a large number of genes that allow them to grow and cause disease on plants. Many these should be induced when the come in contact with plant tissue. We used modified vivo expression technology (IVET) approach identify from pathogen Pseudomonas syringae pv. tomato are upon infection Arabidopsis thaliana isolated over 500 planta-expressed (ipx) promoter fusions. Sequence analysis 79 fusions revealed several known potential virulence genes, including hrp/hrc,...

The structural gene (sigK) for the mother-cell RNA polymerase sigma-factor sigma K in Bacillus subtilis is a composite of two truncated genes, named spoIVCB and spoIIIC, which are brought together by site-specific recombination during sporulation. We now show that event compartmentalized mother cell, but not forespore chromosome, undergoes rearrangement. also spoIIIC (encoding carboxy-terminal portion K) lies approximately 42 kb downstream amino-terminal portion) joining coding sequences...

The bacterial pathogen Pseudomonas syringae modulates plant hormone signaling to promote infection and disease development. P. uses several strategies manipulate auxin physiology in Arabidopsis thaliana pathogenesis, including its synthesis of indole-3-acetic acid (IAA), the predominant form plants, production virulence factors that alter responses host; however, role pathogen-derived pathogenesis is not well understood. Here we demonstrate strain DC3000 produces IAA via a previously...

SUMMARY The jasmonates (JAs) comprise a family of plant hormones that regulate several developmental processes and mediate responses to various abiotic biotic stresses, including pathogens. JA signalling is manipulated by strains the bacterial pathogen Pseudomonas syringae , P. strain DC3000, using virulence factor coronatine (COR) as mimic jasmonyl‐ l ‐isoleucine (JA‐Ile). To better understand JA‐Ile‐mediated contributing disease susceptibility, it important investigate regulation during...

Abstract To accomplish successful infection, pathogens deploy complex strategies to interfere with host defense systems and subvert physiology favor pathogen survival multiplication. Modulation of plant auxin signaling is emerging as a common virulence strategy for phytobacteria cause diseases. However, the underlying mechanisms remain largely elusive. We have previously shown that Pseudomonas syringae type III effector AvrRpt2 alters Arabidopsis (Arabidopsis thaliana) physiology. Here, we...

Auxin is a key plant growth regulator that also impacts plant-pathogen interactions. Several lines of evidence suggest the bacterial pathogen Pseudomonas syringae manipulates auxin physiology in Arabidopsis thaliana to promote pathogenesis. strategies alter host biology include synthesis indole-3-acetic acid (IAA) and production virulence factors responses cells. The application exogenous enhances disease caused by P. strain DC3000. This hypothesized result from antagonism between salicylic...

Abstract The plant hormone auxin is perceived by a family of F-box proteins called the TIR1/AFBs. Phylogenetic studies reveal that these fall into four clades in flowering plants TIR1, AFB2, AFB4, and AFB6. Genetic indicate members TIR1 AFB2 groups act as positive regulators signaling promoting degradation Aux/IAA transcriptional repressors. In this report, we demonstrate both AFB4 AFB5 also function receptors based on vitro assays. We provide genetic evidence are targets picloram auxinic...

Several bacterial avr genes have been shown to contribute virulence on susceptible plants lacking the corresponding resistance (R) gene. The mechanisms by which promote parasitism and disease, however, are not well understood. We investigated role of Pseudomonas syringae pv. tomato avrRpt2 gene in pathogenesis studying interaction P. strain PstDC3000 expressing with several Arabidopsis thaliana lines R gene, RPS2. found that grew significantly higher levels often resulted formation more...

Summary Pseudomonas syringae pv. tomato ( Pst ) strain DC3000 infects the model plants Arabidopsis thaliana and tomato, causing disease symptoms characterized by necrotic lesions surrounded chlorosis. One mechanism used to infect host is type III protein secretion system, which thought deliver multiple effector proteins plant cell. The exact number of effectors in or any other pathogenic bacterium not known. All known genes P. are regulated HrpS, an NtrC family protein, HrpL alternative...