Role Of GAPCs In Autophagy And Plant Immunity

Autophagy is an evolutionarilyconserved catabolic pathway that has multiple rolesin nutrient recycling, development, senescence, abiotic stress responses, and pathogen defense. Plant autophagy can respond to reactive oxygen species(ROS)and plays an important role in degrading oxidized proteins in plants under various stress conditions. However,how ROS regulates autophagy inresponse to oxidative stresses is largely unknown. ATG3 is the E2 like enzyme for ATG8 lipidation process, which is essential forautophagy process. ATG3 is not only a key autophagy component but also a regulator of plant immunity-related cell death. In the thesis, affinity purificationcoupledto MS(AP-MS) was applied to screen potential ATG3-binding proteins. Physiological, biochemical and genetic experiments were designed to better understand the roles of ATG3-interaction proteins in plant autophagy and plant immunity.Cytosolic glyceraldehyde-3-phosphate dehydrogenases(GAPCs), as a key enzyme in the glycolyticpathway, have multiple homologues in plant. But its moonlighting functions in embryo development, pollen development, root growth, lipid metabolism, seed oil accumulation, and ABA signal transduction have also been reported in plants.Here, we show that autophagy-related protein 3(ATG3) interacts with the cytosolic glyceraldehyde-3-phosphate dehydrogenases(GAPCs) to regulate autophagy in plants. We found that oxidative stress inhibits the interaction of ATG3 with GAPCs. Silencing of GAPCs significantly activates ATG3-dependent autophagy whilst overexpression of GAPCs suppresses autophagy in plants. Moreover, silencing of GAPCs enhances N gene-mediated cell death and plant resistance against both incompatible pathogens Tobacco mosaic virusand Pseudomonas syringae pv tomato DC3000(Pst DC3000), as well as compatible pathogen P. syringae pv tabaci.These results indicate that GAPCs have multiple functions in the regulation of autophagyand plant innate immunity.