VvATG18a participates in grape resistance to gray mold induced by BR signaling pathway

Autophagy plays an important role in responding to necrotrophic pathogens and plant signal hormones. Brassinosteroids (BRs) are a class of natural steroidal phytohormones that effectively regulated the disease resistance responses in grape. However, the molecular mechanism of BR-autophagy networks responsible for activation of host defense against gray mold remained to be elucidated. We reported a novel defense mechanism that BR-regulated autophagy in grape berry against gray mold. Exogenous application of 24-epibrassinolide (eBR) enhanced the grape disease resistance. Meanwhile, the endogenous BR was accumulated and BR signaling pathway was activated in the berries. In addition, transcriptome analysis in eBR-treated grapes infected with gray mold showed that the differentially expressed genes (DEGs) were enriched in the metabolic pathway of BR signaling pathway and autophagy. DNA affinity purification sequencing (Dap-seq), Yeast one-hybrid assay (Y1H) and dual luciferase assays (LUC) verified VvBZR1 bound to the promoter of VvATG18a to induce its gene expression. Overexpressing VvATG18a and VvBZR1 improved the resistance of grapes to gray mold. Overall, this study sheds light on the immune mechanisms underlying the involvement of the autophagy in grape innate immunity, highlighting the pivotal role of VvATG18a in enhancing disease resistance.