EDS1-mediated activation of autophagy regulates Pst DC3000 (AvrRps4)-induced programmed cell death in Arabidopsis

Autophagy is a conserved intracellular process through which cytoplasmic components are degraded and recycled under stress conditions. In the innate immunity of higher plants, autophagy has either pro-survival or pro-death functions in pathogen-induced programmed cell death (PCD). In aged leaves, autophagy negatively regulates PCD by eliminating redundant salicylic acid. However, in young leaves, the specific pro-death mechanisms of autophagy and signaling pathways related to the autophagic process have not been elucidated. Here, we demonstrate that enhanced disease susceptibility 1 (EDS1) mediated the activation of autophagy and played a key role in the pro-death mechanism of autophagy during avirulent Pst DC3000 (AvrRps4) infection. The path through which autophagosomes enter the vacuole was blocked. Additionally, formation of the ATG12-ATG5 complex and the level of enzymatic activity associated with ATG8 cleavage decreased in eds1 mutants. The expression of EDS1 in atg5 mutants was also much lower than that in wild-type plants during pathogen-triggered PCD. These findings implied that EDS1 may regulate autophagy by affecting the activities of the two ubiquitin-like protein-conjugating pathways. Moreover, autophagy may regulate immunity-related PCD by affecting the expression of EDS1 in young plants. Our results provide important insights into the mechanisms of EDS1 in autophagy during infection with avirulent Pst DC3000 (AvrRps4) in Arabidopsis.