Characterization of XopN, a Heat-Repeat TTSS Effector Required for Xanthomonas Pathogenesis in Tomato

Stanford University, Stanford CA

Investigators

Abstract

This project seeks to identify critical plant processes affected during bacterial pathogenesis, opening the door to the discovery of alternative methods to control or eliminate plant disease. The investigators will use genetic, biochemical, and cell biological approaches to determine how pathogenic bacteria suppress plant defenses to promote colonization. The disease that will be studied is bacterial spot disease of tomato caused by Xanthomonas campestris pathovar vesicatoria (Xcv). Xcv has evolved a specialized secretion system (referred to as the type III secretion system (TTSS)) to transport 30-35 proteins into the plant cell during infection. The intellectual goal of this project is to determine the biochemical function of XopN, a unique Xcv protein that is highly conserved amongst different Xanthomonas species. The central hypothesis is that XopN interferes with protein-protein interactions in tomato to suppress defense activation. The specific aims are to: (1) characterize XopN protein domains required for Xcv pathogenesis in tomato; (2) characterize a tomato protein that XopN binds to at the plant plasma membrane; and (3) identify and characterize plant pathways specifically modulated by XopN during Xcv infection. Knowledge gain herein will contribute to the mechanistic understanding of microbial pathogenesis and the regulation of defense pathways in plants. Broader Impacts: In the long-term, knowledge gained herein will be used by academia, industry, and the government to address agricultural production, disease prevention, and eradication. In the short-term, the investigators will work with K-12 teachers in Fremont CA and their students to introduce this plant topic. Currently, a plant biology curriculum is not being taught. Emphasis will be to train students and teachers about plant biology, disease, and agriculture - highlighting the importance of the plant sciences and its impact on society.