Abstract

Jasmonic acid acts as an essential phythormone in plant defenses against necrotrophic fungi. This study investigated the immune response induced by damage-associated molecular pattern (DAMP) molecule extracellular self-DNA (sDNA) to resistant Rhizopus stolonifer invasion in postharvest peaches through JA signaling pathway. The results confirmed that perception of sDNA inhibited R. stolonifer colonization and activated MAPK cascades. Yeast two-hybrid (Y2H) and luciferase complementation imaging (LCI) assay indicated the interaction between PpMAPK1 and PpLOX2, implying PpMAPK1 could mediate the function of PpLOX2 protein. Moreover, sDNA induced transcription of JA biosynthesis genes and JA-responsive genes, as well as the master regulator PpMYC2 in JA signaling pathway. Results of electrophoretic mobility shift assay (EMSA) indicated that PpMYC2 activated transcription of JA-responsive genes through directly bound to G-box cis -element in these genes promoter. Additionally, yeast three-hybrid (Y3H) and dual-luciferase reporter analysis (DLR) demonstrated that PpNPR1 interacted with PpMYC2 and performed as a transcriptional suppressor of PpMYC2-targeted JA-responsive genes, implying it participating in regulating antagonistic between JA- and SA-induced defense response. Finally, construction of PpROS1 overexpressor and PpROS1 cas9 mutants in peaches demonstrated that PpMYC2 functioned as a crucial regulator on sDNA-triggered resistance to necrotrophic fungi R. stolonifer via JA signaling pathway. Hence, this study elucidated the importance of JA-induced gene PpMYC2 in response to against R. stolonifer invasion in sDNA-treated postharvest peaches, thus providing insight into the regulatory function of sDNA in the JA signaling pathway.