NPR1, NPR3 and NPR4 Cooperate to Inhibit the Production of Psm ES4326/avrRpt2-Induced Autophagosome via EDS1

Abstract

Abstract Our previous study found that Pseudomonas syringae pv. maculicola (Psm) ES4326/avrRpt2 may induce autophagy via EDS1, which was inhibited by NPR1 (nonexpressor of pathogenesis-related gene 1). In this study, we investigated the roles of EDS1 (enhanced disease susceptibility 1), NPR1, NPR3, NPR4 and their potential cooperation in regulating autophagy induced by Psm ES4326/avrRpt2in Arabidopsis. We confirmed the crucial role of EDS1 and its influence on ATGs (autophagy-related genes) and NBR1 (neighbor of BRCA1 gene 1) under normal and Psm ES4326/avrRpt2 infection. Furthermore, we looked into autophagic flux induced by Psm ES4326/avrRpt2 in GFP-ATG8a/Col (Columbia) and GFP-ATG8a/nprs mutants. The number of autophagosomes in GFP-ATG8a/npr34(npr3npr4) was significantly lower than in GFP-ATG8a/Col, while was significantly higher in GFP-ATG8a/npr134 (npr1npr3npr4) under both normal and Psm ES4326/avrRpt2 treatment. Upon the same treatment, the expression level of NBR1 exhibited a decrease in GFP-ATG8a/npr34but an increase in GFP-ATG8a/npr134 compared with GFP-ATG8a/Col. We further found that the expression of EDS1 and RPS4 in npr134mutant was significantly higher than in Col. The above results suggested that Psm ES4326/avrRpt2 may activate RPS4 to induce the generation of autophagosome through EDS1, and NPR1, NPR4, NPR3 together inhibited the formation of autophagosome.