Race-specific genotypes of Pseudomonas syringae pv. tomato are defined by the presence of mobile DNA elements within the genome

Abstract

Pseudomonas syringae pv. tomato is the causal agent of bacterial speck of tomato, an important disease that results in severe crop production losses worldwide. Currently, two races within phylogroup 01a (PG01a) are described for this pathogen. Race 0 strains have avirulence genes for the expression of type III system-associated effectors AvrPto1 and AvrPtoB, that are recognized and targeted by the effector-triggered immunity in tomato cultivars having the pto race-specific resistance gene. Race 1 strains instead lack the avrPto1 and avrPtoB genes and are therefore capable to aggressively attack all tomato cultivars. Here, we have performed the complete genome sequencing and the analysis of P. syringae pv. tomato strain DAPP-PG 215, which was described as a race 0 strain in 1996. Our analysis revealed that its genome comprises a 6.2 Mb circular chromosome and two plasmids (107 kb and 81 kb). The results indicate that the strain is phylogenetically closely related to strains Max13, K40, T1 and NYS-T1, all known race 1 strains. The chromosome of DAPP-PG 215 encodes race 1-associated genes like avrA and hopW1 and lacks race 0-associated genes like hopN1, giving it a race 1 genetic background. However, the genome harbors a complete ortholog of avrPto1, which allows the strain to display a race 0 phenotype. Comparative genomics with several PG01a genomes revealed that mobile DNA elements are rather involved in the evolution of the two different races.

Combat phytopathogenic bacteria employing Argirium-SUNCs: limits and perspectives

“…Through a transcriptomic approach carried out on the P. syringae pv. tomato strain used in the study of Orfei et al ( 2023a ), whose genome we recently sequenced (Orfei et al 2023b ) to better perform the transcriptomic analysis, we demonstrated that the exposition of bacterial cells for 10 and 30 min at sub-letal doses of Argirium - SUNCs induced change in the expression of genes associated with transporters ( e . g ., CadA P-type ATPase, the arsenite resistance efflux pump, multidrug resistance proteins), iron homeostasis ( e .…”

Tomato and Pepper Seeds as Pathways for the Dissemination of Phytopathogenic Bacteria: A Constant Challenge for the Seed Industry and the Sustainability of Crop Production

“…Typical symptoms of the bacterial speck consist in small and dark lesions on leaves, usually surrounded by a yellow halo, and necrotic spots along stems and on fruits, provoked by a coronatine toxin; from necrotic lesions the germs can evade the plant as bacterial exudates and spread around. The disease can lead to yield reductions as a result from defoliation, flower abortion and fruit lesions [48,49]. The damages caused by Pst can be remarkable in nurseries, greenhouses, and fields during warm and humid conditions [50].…”