P-176 - Unravelling the functions of Xanthomonas effectors during Brassica infection

Xanthomonas campestris pv. campestris (Xcc) is a vascular pathogen that causes black rot disease in Brassica oleracea, including cabbage and other cruciferous plants. Xcc enters the plant via hydathode pores at leaf margins from where it proceeds to colonize the leaf vasculature and spread systemically. Major Resistance (R)-gene based resistance has not yet been identified in B. oleracea cultivars. Therefore, this project aims to identify novel resistance mechanisms by leveraging host susceptibility (S) genes. For successful infection, Xcc relies on Type-3 secretion system to deliver Type-3 effector (T3E) proteins inside the plant cell to enhance virulence by manipulating host physiology or by supressing plant immunity. As the targets of T3Es in the host cell may represent key pathways facilitating Xcc infection, we aim to identify these host proteins which represent potential S genes and engineer them to acquire disease resistance. To identify effector targets, we employ a pipeline in B. oleracea using transient gene expression and TurboID-based proximity labelling followed by mass-spectrometry for protein identification. The function of the identified gene candidates in disease resistance and host physiology will be further studied in Arabidopsis thaliana and B. oleracea.  Thus, this study aims to identify host targets of Xcc T3Es, unravel the mechanisms for susceptibility in B. oleracea and develop durable resistance against the pathogen.