Avirulence geneavrPpiAfromPseudomonas syringaepv.pisiis not required for full virulence on pea

Gibbon, Marjorie J.; Jenner, Carol E.; Mur, Luis A. J.; Puri, Nakul; Mansfıeld, John W.; Taylor, John D.; Vivian, Alan

doi:10.1006/pmpp.1997.0083

Cited by 13 publications

(11 citation statements)

References 47 publications

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“…pv. pisi has not been found to affect pathogenicity on pea (Gibbon et al ., 1997). Water soaking of cotton by X. campestris pv.…”

Section: Discussionmentioning

confidence: 99%

“…maculicola, a reduction in pathogenicity has been determined (Ritter and Dangl, 1995), whereas, in simple pathogenicity tests with avrPphE mutants of Psph and avrPpiA mutants of P. s. pv. pisi, no differences in pathogenicity were recorded (Mansfield et al, 1994;Gibbon et al, 1997).…”

Section: Introductionmentioning

confidence: 93%

“…pv. pisi , no differences in pathogenicity were recorded (Mansfield et al ., 1994; Gibbon et al ., 1997).…”

Section: Introductionmentioning

confidence: 99%

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Sequence variations in alleles of the avirulence gene avrPphE.R2 from Pseudomonas syringae pv. phaseolicola lead to loss of recognition of the AvrPphE protein within bean cells and a gain in cultivar‐specific virulence

Stevens

Bennett

Athanassopoulos

et al. 1998

Molecular Microbiology

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SummaryThe bean halo blight pathogen, Pseudomonas syringae pv. phaseolicola (Psph), is differentiated into nine races based on the presence or absence of five avirulence (avr ) genes in the bacterium, which interact with corresponding resistance genes, R1-R5, in Phaseolus vulgaris. The resistance gene R2 is matched by avrPphE, which is located adjacent to the cluster of hrp genes that are required for pathogenicity of Psph. Although only races 2, 4, 5 and 7 are avirulent on cultivars with R2 (inducing the hypersensitive response; HR), homologues of avrPphE are present in all races of Psph. DNA sequencing of avrPphE alleles from races of Psph has demonstrated two routes to virulence: via single basepair changes conferring amino acid substitutions in races 1, 3, 6 and 9 and an insertion of 104 bp in the allele in race 8. We have demonstrated that these base changes are responsible for the difference between virulence and avirulence by generating transconjugants of a virulent race harbouring plasmids expressing the various alleles of avrPphE. Agrobacterium tumefaciens-directed expression of avrPphE from race 4 in bean leaves induced the HR in a resistance gene-specific manner, suggesting that the AvrPphE protein is alone required for HR induction and is recognized within the plant cell. The allele from race 6, which is inactive if expressed in Psph, elicited a weak HR if expressed in planta, whereas the allele from race 1 did not. Our results suggest that the affinity of interaction between AvrPphE homologues and an unknown plant receptor mediates the severity of the plant's response. Mutation of avrPphE alleles did not affect the ability to colonize bean from a low level of inoculum. The avirulence gene avrPphB, which matches the R3 resistance gene, also caused a gene-specific HR following expression in the plant after delivery by A. tumefaciens.

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“…pv. pisi has not been found to affect pathogenicity on pea (Gibbon et al ., 1997). Water soaking of cotton by X. campestris pv.…”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 93%

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Sequence variations in alleles of the avirulence gene avrPphE.R2 from Pseudomonas syringae pv. phaseolicola lead to loss of recognition of the AvrPphE protein within bean cells and a gain in cultivar‐specific virulence

Stevens

Bennett

Athanassopoulos

et al. 1998

Molecular Microbiology

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“…The region chosen in race 2 contained a gene, avrPpiA2, which confers avirulence toward pea cultivars carrying the R2 resistance gene (Dangl et al, 1992;Gibbon et al, 1997). The race 4B strain lacks aurPpiA and a region of DNA associated with it.…”

Section: Discussionmentioning

confidence: 99%

A dispensable region of the chromosome which is associated with an avirulence gene in Pseudomonas syringae pv. pisi

Arnold

Brown²,

Jackson³

et al. 1999

Microbiology

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Lane, Bristol 8516 IQY, UK Pseudomonas syringae pv. pisi comprises a number of races which fall into two phylogenetically distinct groups (designated I and 11). Races are based on cultivar specificity in the host plant, pea (Pisum sativum), and are specified by the presence of avirulence genes. The avirulence gene avrPpiAl is present on the chromosome of all strains examined in race 2, which belongs to phylogenetic group II. A race 4B strain, from phylogenetic group I , lacks this avirulence gene and a comparative study was made of the chromosome in strains representing these two races. A race 2 cosmid clone (pAV270) carrying avrPpiA1 was used as a basis for collinearity analysis of races 2 and 4B. A region of the chromosome amounting to 8 5 kb and including avrPpiA1 was absent from race 46 compared with race 2. A fragment spanning the junction of the discontinuity in race 4B was isolated, cloned and used to delimit the extent of the additional DNA present in race 2. In both races the borders of the discontinuity contained DNA sequences which showed a high degree of conservation. A 7 bp slightly imperfect direct repeat (CCAGCT/,T) flanked the additional DNA in race 2, with a single copy in race 46. The region flanking the additional DNA was present in all races of P. syringae pv. phi. These results confirm the phylogenetic groupings in P. syringae pv. pisi.

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“…The deletion of certain avr genes causes a reduction in pathogenic fitness, as indicated by reduced rates of multiplication and disease symptom production in susceptible cultivars of the host plant (Chang et al ., 2000; Chen et al ., 2000; Lorang et al ., 1994; Ritter and Dangl, 1995). However, because of the presence of multiple vir genes, possibly with similar functions, the inactivation of individual avr genes often has no effect on basic pathogenicity (Gibbon et al ., 1997; Vivian and Arnold, 2000; Vivian et al ., 2001).…”

Section: Introductionmentioning

confidence: 99%

Location and activity of members of a family of virPphA homologues in pathovars of Pseudomonas syringae and P. savastanoi

Jackson

Mansfıeld

Ammouneh

et al. 2002

Molecular Plant Pathology

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Summary virPphA is a major determinant of the pathogenicity of Pseudomonas savastanoi pv. phaseolicola to Phaseolus bean. A family of homologues of virPphA was detected in pathovars of P . savastanoi and P . syringae . We examined the structure and activity of alleles designated virPphA , virPphA Pgy , and virPphA Psv from P . savastanoi pathovars phaseolicola , glycinea , and savastanoi , respectively, and avrPtoB from P . syringae pv. tomato . Sequencing showed that the virPphA Pgy homologue had a 48‐bp central deletion in the open reading frame (ORF) compared with virPphA and virPphA Psv , but otherwise all three P . savastanoi alleles had > 98% identity at the DNA level. By contrast, AvrPtoB from P . syringae pv. tomato strain DC3000 was predicted to have only 51% amino acid similarity with VirPphA. All ORFs have an upstream hrp ‐box promoter indicating potential regulation by HrpL. Each cloned homologue was introduced into the P. savastanoi pv. phaseolicola strain RW60, which lacks a native plasmid carrying virPphA as part of a pathogenicity island (PAI), and which is not pathogenic on bean. The homologues all restored virulence, as measured by the development of water‐soaked lesions in bean pods, and increased bacterial populations in leaves compared with RW60 alone. RW60 harbouring virPphA or virPphA Psv elicited a strong hypersensitive reaction (HR) in soybean cv. Osumi; the presence of avrPtoB caused a weak HR, but virPphA Pgy did not affect the null reaction observed in soybean with RW60 alone. A second effector gene, avrPphD , was detected on the genomic clones carrying virPphA Pgy and virPphA Psv . avrPphD was also present in both P . savastanoi pv. phaseolicola and P . syringae pv. tomato , but elsewhere in their genomes. Comparison of the genomic locations of virPphA and other effectors found in the P. savastanoi pv. phaseolicola PAI revealed the greatest divergence of the sequences surrounding virPphA to be in ...

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Avirulence geneavrPpiAfromPseudomonas syringaepv.pisiis not required for full virulence on pea

Cited by 13 publications

References 47 publications

Sequence variations in alleles of the avirulence gene avrPphE.R2 from Pseudomonas syringae pv. phaseolicola lead to loss of recognition of the AvrPphE protein within bean cells and a gain in cultivar‐specific virulence

Sequence variations in alleles of the avirulence gene avrPphE.R2 from Pseudomonas syringae pv. phaseolicola lead to loss of recognition of the AvrPphE protein within bean cells and a gain in cultivar‐specific virulence

A dispensable region of the chromosome which is associated with an avirulence gene in Pseudomonas syringae pv. pisi

Location and activity of members of a family of virPphA homologues in pathovars of Pseudomonas syringae and P. savastanoi

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