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Comparative genomics and genomic diversity of Pseudomonas syringae clade 2b-a in Australia

Authors :
Noel Djitro
Rebecca Roach
Rachel Mann
Paul R. Campbell
Brendan Rodoni
Cherie Gambley
Source :
BMC Microbiology, Vol 22, Iss 1, Pp 1-14 (2022)
Publication Year :
2022
Publisher :
BMC, 2022.

Abstract

Abstract Background A zucchini disease outbreak with unusual symptoms associated with Pseudomonas syringae clade 2b was identified in Bundaberg, Australia during autumn 2016. To investigate the genetic diversity of the 11 Australian isolates obtained from the outbreak, the genomes were compared to the publicly available P. syringae strains in phylogroup 2. Results Average nucleotide identity refined the P. syringae clade 2b-a into four clusters (Cluster A, B, C1 and C2), an expansion from the previously identified A, B and C. Australian isolates were in Cluster A, C1 and C2. Genomic analyses highlighted several key factors that may contribute to the virulence of these isolates. Six orthologous groups, including three virulence factors, were associated with P. syringae phylogroup 2 cucurbit-infecting strains. A region of genome plasticity analysis identified a type VI secretion system pathway in clade 2b-a strains which could also contribute to virulence. Pathogenicity assays on isolates KL004-k1, KFR003-1 and 77-4C, as representative isolates of Cluster A, C1 and C2, respectively, determined that all three isolates can infect pumpkin, squash, watermelon and zucchini var. Eva with different levels of disease severity. Subsequently, type III effectors were investigated and four type III effectors (avrRpt2, hopZ5, hopC1 and hopH1) were associated with host range. The hopZ effector family was also predicted to be associated with disease severity. Conclusions This study refined the taxonomy of the P. syringae clade 2b-a, supported the association between effector profile and pathogenicity in cucurbits established in a previous study and provides new insight into important genomic features of these strains. This study also provided a detailed and comprehensive resource for future genomic and functional studies of these strains.

Details

Language :
English
ISSN :
14712180
Volume :
22
Issue :
1
Database :
Directory of Open Access Journals
Journal :
BMC Microbiology
Publication Type :
Academic Journal
Accession number :
edsdoj.6689bc5a81f4928b0ea81adf6e70b93
Document Type :
article
Full Text :
https://doi.org/10.1186/s12866-022-02678-9