P-017 - Chloroplast immunity: a neglected, but promising mechanism to enhance sustainable agriculture

Biotic stress can lead to losses exceeding 25% of the crop yield.  In order to avoid that, it is crucial to investigate all feasible approaches to limit pathogen infections. Chloroplast immunity is an emerging field, and increasing evidence highlights chloroplasts as a common pathogen virulence target. Using the model Arabidopsis thaliana - Pseudomonas syringae pv. tomatoDC3000 (DC3000) pathosystem we demonstrated that recognition of pathogen-associated molecule pattern (PAMP) generates a burst of chloroplast derived reactive oxygen species (ROS). In response, pathogens produce and deliver proteins (effectors) to suppress ROS production. My project incorporates proteomics, genetics and cell biology to better understand how pathogens suppress chloroplast immunity.

Proteomic data comparing infection of A. thaliana leaves with pathogenic DC3000 and the non-pathogenic DC3000 HrpA mutant revealed over 240 proteins with a statistically significant change in abundance. Screening of Arabidopsis mutants led to a focus on the role in the immune system of Psb27, a protein intimately involved in the repair of photosystem II. The possible effector candidate to be responsible for the chlorophyll fluorescence suppression of Psb27 mutant is now narrowed to 8 effectors.

Other research avenues involve investigating the function of a chloroplast-localised effector (HopO1-2) and examining the difference in size and shape of chloroplasts following infection using flow cytometry.