Abstract
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 P. syringae pv. tomato.
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Claims 9
Claim · model-written summary
The virPphA homologues restored virulence of strain RW60 on bean, measured as water-soaked lesions in pods.
Verbatim
e1“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”
Claim · model-written summary
The virPphA homologues increased bacterial populations in bean leaves compared with RW60 alone.
Verbatim
e1“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”
Claim · model-written summary
RW60 harbouring virPphA or virPphA(Psv) elicited a strong hypersensitive reaction in soybean cv. Osumi.
- Taxon
- soybean
Glycine maxe2 - Material
- cv. Osumie2
- Treatment
- RW60 harbouring virPphA or virPphA(Psv)e2
- Interactor
- RW60e2pathogen
- Outcome
- hypersensitive reactione2
- Qualifier
- stronge2
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“RW60 harbouring virPphA or virPphA(Psv) elicited a strong hypersensitive reaction (HR) in soybean cv. Osumi”
Claim · model-written summary
The presence of avrPtoB caused a weak hypersensitive reaction in soybean.
- Taxon
- soybeanGlycine maxe3
- Treatment
- the presence of avrPtoBe3
- Outcome
- HRe3
- Qualifier
- weake3
- Comparator
- RW60 alonee3
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e3“the presence of avrPtoB caused a weak HR, but virPphA(Pgy) did not affect the null reaction observed in soybean with RW60 alone”
Claim · model-written summary
virPphA(Pgy) did not affect the null reaction in soybean relative to RW60 alone.
- Taxon
- soybeanGlycine maxe3
- Treatment
- virPphA(Pgy)e3
- Outcome
- null reactione3
- Direction
- did not affecte3
- Comparator
- RW60 alonee3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e3“the presence of avrPtoB caused a weak HR, but virPphA(Pgy) did not affect the null reaction observed in soybean with RW60 alone”
Claim · model-written summary
avrPphD is present in both P. savastanoi pv. phaseolicola and P. syringae pv. tomato, but at other genomic locations.
Verbatim
e4“avrPphD was also present in both P. savastanoi pv. phaseolicola and P. syringae pv. tomato, but elsewhere in their genomes”
Claim · model-written summary
Sequences surrounding virPphA diverge most in P. syringae pv. tomato.
Verbatim
e5“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 P. syringae pv. tomato”
Claim · model-written summary
The three P. savastanoi virPphA alleles had more than 98% DNA identity.
Verbatim
e6“all three P. savastanoi alleles had > 98% identity at the DNA level”
Claim · model-written summary
AvrPtoB from P. syringae pv. tomato strain DC3000 was predicted to have only 51% amino acid similarity with VirPphA.
Verbatim
e7“AvrPtoB from P. syringae pv. tomato strain DC3000 was predicted to have only 51% amino acid similarity with VirPphA”