(300-51) An ESCRT-interacting deubiquitinase (AMSH1) is involved in the hypersensitive response (HR) and nonhost resistance (NHR) against powdery mildew fungi in Arabidopsis
Research Assistant University of Maryland College Park Rockville, Maryland
Body of Abstract: Plant nonhost resistance (NHR) is a phenomenon in which all genotypes of a plant species are immune to all strains of a phytopathogen. While there is great interest in understanding NHR to facilitate engineering robust disease resistance in crops, the molecular basis of NHR remains poorly characterized. It is known that MAMP-trigged immunity (MTI) and effector-triggered immunity (ETI) contribute to NHR; however, studying NHR against non-adapted filamentous pathogens is difficult because it often consists of multiple layers and lacks intraspecific variation. To circumvent this difficulty, we first made an immunocompromised Arabidopsis quintuple mutant, eds1-pad4-sid2-pen1-pen2 (epsp1p2), that has compromised resistance against non-adapted dicot powdery mildews but remains largely immune to barley mildew, Blumeria graminis f. sp. hordei (Bgh). We then performed a genetic screen with epsp1p2 for mutants susceptible to non-adapted Bgh (snab). The snab1 mutant supports sporulation of Bgh, indicating considerable breakdown of NHR. The causal mutation was mapped to ASSOCIATED MOLECULE WITH THE SH3 DOMAIN OF STAM1 (AMSH1) which encodes a deubiquitinase that interacts with endosomal sorting complex required for transport (ESCRT) machinery. ESCRT is involved in several cellular processes, including degradation of membrane proteins and autophagy. Our preliminary data suggest that AMSH1 is required for the hypersensitive response (HR), a type of localized programmed cell death associated with classic ETI that helps restrict pathogen grown. Thus, our results implicate ESCRT components in the regulation of plant immunity.