Characterisation of the pathogenicity of strains of Pseudomonas syringae towards cherry and plum

Abstract

Bacterial canker is a major disease of cherry and other stone fruits caused by several pathovars of Pseudomonas syringae . These are P.s pv. morsprunorum race 1 (Psm R1), P.s pv. morsprunorum race 2 (Psm R2) and P.s pv. syringae (Pss). Psm R1 and R2 were originally designated as races of the same pathovar, however phylogenetic analysis has revealed them to be distantly related. This study characterised the pathogenicity of P. syringae on cherry and plum, in the field and the laboratory. The field experiment identified variation in host cultivar susceptibility to the different pathogen clades. The cherry cultivar Merton Glory exhibited a broad resistance to all clades, whilst cultivar Van showed race-specific resistance. Psm R1 may be divided into a race structure with some strains pathogenic to both cherry and plum and others only pathogenic to plum. The results of laboratory-based pathogenicity tests were compared to results obtained on whole-trees. Only cut shoot inoculations were found to be sensitive enough to detect cultivar variation in susceptibility. Measuring population growth of bacteria in detached leaves reliably discriminated pathogens from non-pathogens. In addition, symptom appearance discriminated Psm races from non-pathogens which triggered a rapid hypersensitive response (HR). The pathogen Pss rapidly induced disease lesions and therefore may exhibit a more necrotrophic lifestyle than hemi-biotrophic Psm races. This in-depth study of pathogenic interactions, identification of host resistance and optimisation of laboratory assays, will provide a framework for future genetic dissection of virulence and host resistance mechanisms.

Plant phenotyping relevance

植物病害の感受性・症状を評価する病原性試験を比較し、圃場・実験室アッセイの感度と識別性能を検証・最適化しており、病害表現型の取得法が中心的です。

Code and data availability

The paper's phenotyping measurements (disease scores, necrosis lengths, population counts) are presented only in figures; no public phenotype dataset, image collection, or author analysis code is deposited. The only public identifiers are genome sequencing accessions (PRJNA345357, GenBank), which are molecular omics, a

No evidence-backed public reproduction asset is currently recorded.