GSE87643 O antigen acts as a shield to delay early plant immune recognition of the pathogenic bacterium, Xylella fastidiosa

In this study, we demonstrate that the xylem-limited bacterium, Xylella fastidiosa, which lacks a T3SS, utilizes an alternative strategy to delay elicitation of innate immune responses. By decorating its LPS PAMP molecule with a high molecular weight O antigen, this bacterium physically masks itself from early recognition by the grapevine innate immune system. We have elucidated the chemical structure of the O antigen and found that it is primarily an α1,2-linked rhamnan polymer. X. fastidiosa cells lacking O antigen elicited hallmarks of PTI such as ROS production, specifically in the plant xylem tissue compartment, which is comprised primarily of non-living cells. By coupling histological and genome-wide transcriptional profiling, we demonstra te that X. fastidiosa lacking its O antigen shield activates defense-related genes in grapevine. This includes a stronger and more prolonged oxidative burst at concentrations high enough to inhibit pathogen proliferation. To begin exploring translational applications of our findings, we also demonst rate that purified X. fastidiosa LPS elicitor can prime grapevine defenses, thereby conferring host tolerance to subsequent challenge with X. fastidiosa.
Source: GEO: Gene Expression Omnibus - Category: Genetics & Stem Cells Tags: Expression profiling by high throughput sequencing Vitis vinifera Source Type: research