Signalling requirements for Erwinia amylovora‐induced disease resistance, callose deposition and cell growth in the non‐host Arabidopsis thaliana

Abstract

Erwinia amylovora is the causal agent of the fire blight disease in some plants of the Rosaceae family. The non-host plant Arabidopsis serves as a powerful system for the dissection of mechanisms of resistance to E. amylovora. Although not yet known to mount gene-for-gene resistance to E. amylovora, we found that Arabidopsis activated strong defence signalling mediated by salicylic acid (SA), with kinetics and amplitude similar to that induced by the recognition of the bacterial effector avrRpm1 by the resistance protein RPM1. Genetic analysis further revealed that SA signalling, but not signalling mediated by ethylene (ET) and jasmonic acid (JA), is required for E. amylovora resistance. Erwinia amylovora induces massive callose deposition on infected leaves, which is independent of SA, ET and JA signalling and is necessary for E. amylovora resistance in Arabidopsis. We also observed tumour-like growths on E. amylovora-infected Arabidopsis leaves, which contain enlarged mesophyll cells with increased DNA content and are probably a result of endoreplication. The formation of such growths is largely independent of SA signalling and some E. amylovora effectors. Together, our data reveal signalling requirements for E. amylovora-induced disease resistance, callose deposition and cell fate change in the non-host plant Arabidopsis. Knowledge from this study could facilitate a better understanding of the mechanisms of host defence against E. amylovora and eventually improve host resistance to the pathogen.

Flp, a Fis‐like protein, contributes to the regulation of type III secretion and virulence processes in the phytopathogen Xanthomonas campestris pv. campestris

“…Callose deposition assay was performed on cabbage leaves as recently described by Hamdoun et al (). Thirty‐day‐old cabbage leaves were inoculated with Xcc strains by infiltration (detailed above).…”

Anti-Virulence Strategy of Novel Dehydroabietic Acid Derivatives: Design, Synthesis, and Antibacterial Evaluation

“…Additionally, bacterial motility and flagella facilitate cell colonization and adhesion [55]. Erwinia amylovora develops many VFs to overcome the plant immune system and facilitate infection [56]. The bacterium Xanthomonas campestris pv.…”

Microbial pathogenesis and the evasion strategies from the legume plant protective immunity

“…The most abundant species of plant pathogens include Agrobacterium spp., Erwinia spp., Pseudomonas spp., Ralstonia spp., and Xanthomonas spp., which are usually disseminated by various biotic and abiotic factors; and their entry into plants takes place through plants wounds/natural openings like lenticels, hydathodes, or stomata followed by their possession of the inter cellular spaces called apoplast of various tissues/xylem (Abramovitch et al, 2006). Despite plants possess innate cellular immunity against microbial pathogens, specific phytopathogens including bacteria, viruses, and fungi can escape the immunity thereby facilitating plant diseases with concomitant loss in crop yield (Abramovitch et al, 2006; Brown & Allen, 2004; Buttimer et al, 2017; Chen et al, 2020; Cruz et al, 2010; Enebe & Babalola, 2019; González et al, 2007; Hamdoun et al, 2018; Kashyap et al, 2022; Marković et al, 2022; Moral & Trapero, 2012; Nazarov et al, 2020; Nion & Toyota, 2015; Soni et al, 2022; Varun et al, 2017; Zhang et al, 2018; Zhao et al, 2016).…”