Two Different Classes of<i>avrD</i>AllelesOccur in Pathovars of<i>Pseudomonas syringae</i>

Yucel, I.; Boyd, Carol; Debnam, Q; Nt, Keen

doi:10.1094/mpmi-7-0131

Cited by 26 publications

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“…The minimum sequence difference observed was 1.2% between the two bean isolates of P. syringae pv. syringae, a value that is relatively high when other interstrain sequence comparisons of plasmid-borne P. syringae genes are considered (4,44,46). The percent divergence among rulA alleles observed in our study is similar to that observed for four chromosomal loci of P. syringae examined by Sawada et al (33).…”

Section: Discussionsupporting

confidence: 81%

“…Sequence comparisons of plasmid-borne P. syringae genes have been reported for the avirulence gene avrD (three pathovars), a 650-bp region internal to the coronafacate ligase (cfl) gene within the coronatine biosynthetic cluster (four pathovars), and the efe gene encoding the ethylene-forming enzyme (five pathovars) (4,23,44,46). In contrast to results with gyrB, hrpL, hrpS, rulA, and rpoD, relatively few sequence differences were observed, even among pathovars.…”

Section: Discussionmentioning

confidence: 99%

“…pPT23A-type plasmids are diverse in size, and multiple plasmids sharing large regions of repeated sequences may be present in the same cell (3,8,30,35). Plasmids in the pPT23A family can encode determinants of importance in host-pathogen interactions such as the coronatine biosynthesis locus, which increases virulence, and the avirulence genes avrD, avrPphC, and avrPphF, which affect host range (1,21,46). Additional sequences known to be encoded on plasmids of the pPT23A family include the stbCBAD locus involved in plasmid stability (18), copper resistance determinants (6) and the streptomycin resistance transposon Tn5393 (39), and insertion sequence elements including IS51, IS801, IS870, and IS1240 (1,18,30).…”

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Sequence Diversity of rulA among Natural Isolates of Pseudomonas syringae and Effect on Function of rulAB -Mediated UV Radiation Tolerance

Sundin

Jacobs

Murillo

2000

Appl Environ Microbiol

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The rulAB locus confers tolerance to UV radiation and is borne on plasmids of the pPT23A family in Pseudomonas syringae. We sequenced 14 rulA alleles from P. syringae strains representing seven pathovars and found sequence differences of 1 to 12% within pathovar syringae, and up to 15% differences between pathovars. Since the sequence variation within rulA was similar to that of P. syringae chromosomal alleles, we hypothesized that rulAB has evolved over a long time period in P. syringae. A phylogenetic analysis of the deduced amino acid sequences of rulA resulted in seven clusters. Strains from the same plant host grouped together in three cases; however, strains from different pathovars grouped together in two cases. In particular, the rulA alleles from P. syringae pv. lachrymans and P. syringae pv. pisi were grouped but were clearly distinct from the other sequenced alleles, suggesting the possibility of a recent interpathovar transfer. We constructed chimeric rulAB expression clones and found that the observed sequence differences resulted in significant differences in UV (wavelength) radiation sensitivity. Our results suggest that specific amino acid changes in RulA could alter UV radiation tolerance and the competitiveness of the P. syringae host in the phyllosphere.The pPT23A plasmid family encompasses the majority of native plasmids identified in the plant-pathogenic bacterium Pseudomonas syringae; these plasmids share a gene (repA) required for plasmid replication and, in most cases, additional areas of homology (16,30,35,38). pPT23A-type plasmids are diverse in size, and multiple plasmids sharing large regions of repeated sequences may be present in the same cell (3,8,30,35). Plasmids in the pPT23A family can encode determinants of importance in host-pathogen interactions such as the coronatine biosynthesis locus, which increases virulence, and the avirulence genes avrD, avrPphC, and avrPphF, which affect host range (1,21,46). Additional sequences known to be encoded on plasmids of the pPT23A family include the stbCBAD locus involved in plasmid stability (18), copper resistance determinants (6) and the streptomycin resistance transposon Tn5393 (39), and insertion sequence elements including IS51, IS801, IS870, and IS1240 (1, 18, 30). A common feature of all of these determinants is that functional loci encoding these traits are typically limited in distribution to small groups of P. syringae pathovars.Given the distribution of the pPT23A plasmid family throughout P. syringae pathovars, it is likely that these plasmids encode a "backbone" of traits of general importance to the P. syringae species. We are interested in the evolution of the pPT23A plasmid family in P. syringae, including determining the range of pathovars encompassed by particular plasmid lineages, characterizing genes encoded on these plasmids, and delineating the importance of horizontal transfer in pPT23A plasmid biology. In a previous study, we suggested that subgroups of pPT23A-like plasmids formed stable cohesive lineages as defined...

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Section: Discussionsupporting

confidence: 81%

Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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Sequence Diversity of rulA among Natural Isolates of Pseudomonas syringae and Effect on Function of rulAB -Mediated UV Radiation Tolerance

Sundin

Jacobs

Murillo

2000

Appl Environ Microbiol

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“…Outstanding examples are the genes involved in the biosynthesis of the phytotoxin coronatine (Sato, 1988 ;Bender et al, 1999), auxins (Comai & Kosuge, 1980 ;Glickmann et al, 1998) and avr genes (Vivian et al, 1997). In some cases, related genes or gene clusters are conserved in unrelated pathovars ; examples of this include the coronatine biosynthetic cluster which is present in five pathovars (Mitchell, 1982 ;Wiebe & Campbell, 1993 ;Cuppels & Ainsworth, 1995) and avrD sequences which have been detected within a wide pathovar range (Yucel et al, 1994). However, the relationships among different native plasmids from P. syringae have not been studied extensively and authors have reported both similarity and dissimilarity among plasmids from a given pathovar (Curiale & Mills, 1983 ;Denny, 1988 ;King, 1989 ;Sundin et al, 1994).…”

Section: Abbreviations : Ap-pcr Arbitrarily Primed Pcr ; Eric Extramentioning

confidence: 99%

Phylogeny of the replication regions of pPT23A-like plasmids from Pseudomonas syringae The EMBL accession numbers for the sequences reported in this paper are AJ276998–AJ277021.

2000

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It was previously shown that most Pseudomonas syringae strains contain one or more plasmids with cross-hybridizing replication regions and other areas of homology, and these plasmids were designated the pPT23A-like family. The majority of these plasmids encode genes conferring epiphytic fitness or resistance to antibacterial compounds and those investigated in this study are essential for pathogenicity or increased virulence. The phylogeny of 14 pPT23A-like plasmids from five P. syringae pathovars was studied by comparing a fragment of the sequence of their repA genes (encoding a replicase essential for replication). In the phylogenetic tree obtained, four groups (Z 888% identity between their members) could be identified. The first group contained the plasmids from three P. syringae pv. tomato strains, a P. syringae pv. apii strain and five out of the seven P. syringae pv. syringae strains, with identity ranging between 888 and 100 %. The clustering of the pv. syringae strains did not reflect host specialization or previously reported phylogenetic relationships. The second group contained the plasmids from two strains of pv. glycinea and pv. tomato (955 % identity), and it also included the previously sequenced replicon of a pathogenicity plasmid from P. syringae pv. phaseolicola. The plasmids from the remaining two pv. syringae strains were distantly related to the other plasmid sequences. Hybridization experiments using different genes or transposable elements previously described as plasmid-borne in P. syringae, showed that the gene content of highly related plasmids could be dissimilar, suggesting the occurrence of major plasmid reorganizations. Additionally, the phylogeny of the different native plasmids did not always correlate with the phylogeny of their harbouring strains, as determined by the analysis of extragenic repetitive consensus (ERIC) and arbitrarily primed PCR (AP-PCR) products. Collectively, these results suggest that pPT23A-like plasmids were, in most cases, acquired early during evolution.

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“…All the races of Psg, including race 4 (represented in this study by isolate 2478), have previously been shown to harbour inactive homologues of the avirulence gene avrD from P. syringae pv. tomato (Wolfson Keith et al ., 1997), as have a range of other P. syringae pathovars including Psph (Yucel et al ., 1994). The cultivar‐specific resistant responses of some of the nonhost plant species towards isolates 1704B (Psp), 1299A (Psph) and 2478 (Psg) (Table 4), none of which carry avirulence genes detectable on their respective specific host species, showed them to carry ‘cryptic’ functional avirulence genes that matched resistances in these nonhost species.…”

Section: Discussionmentioning

confidence: 99%

Patterns of interaction between isolates of three pathovars of Pseudomonas syringae and accessions of a range of host and nonhost legume species

Hunter¹,

Taylor²

2005

Plant Pathology

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Isolates of three pathovars of Pseudomonas syringae were tested against 10 legume species. Some isolates of all pathovars showed cultivar-specific interactions with at least one legume species outside the expected host range. Lablab purpureus and Phaseolus lunatus were found to be hosts to isolates of both P. syringae pv. glycinea and P. syringae pv. phaseolicola, while Lathyrus latifolius was host to isolates of P. syringae pv. pisi and P. syringae pv. glycinea . Lens culinaris showed patterns of interaction with isolates of all three pathovars. Gene models based on mathematical estimates of minimum gene numbers agreed with those previously published for the interactions of P. syringae pv. pisi with Pisum sativum and P. syringae pv. phaseolicola with Phaseolus vulgaris. Two different gene-for-gene models based on five resistance/avirulence gene pairs were proposed to explain observed interactions between Glycine max and P. syringae pv . glycinea . Pathogen isolates which contained no known avirulences defined on their respective host species were found to carry cryptic avirulences recognized by other plant species. Estimates of minimum gene numbers required to explain the interactions of a plant species with all pathogen isolates or to explain the interactions of the isolates of one pathovar with all plant accessions were consistently lower than the sum of the minimum gene numbers required to explain the interactions of each individual component.

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Two Different Classes ofavrDAllelesOccur in Pathovars ofPseudomonas syringae

Cited by 26 publications

References 0 publications

Sequence Diversity of rulA among Natural Isolates of Pseudomonas syringae and Effect on Function of rulAB -Mediated UV Radiation Tolerance

Sequence Diversity of rulA among Natural Isolates of Pseudomonas syringae and Effect on Function of rulAB -Mediated UV Radiation Tolerance

Phylogeny of the replication regions of pPT23A-like plasmids from Pseudomonas syringae The EMBL accession numbers for the sequences reported in this paper are AJ276998–AJ277021.

Patterns of interaction between isolates of three pathovars of Pseudomonas syringae and accessions of a range of host and nonhost legume species

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