Post-Harvest Quality Changes and Molecular Responses of Epidermal Wax in ‘Munage’ Grapes with Botrytis cinerea Infection

This study aimed to investigate the impact of Botrytis cinerea (<i>B. cinerea</i>) on the post-harvest quality of 'Munage' grapes and their molecular mechanism. The results showed that <i>B. cinerea</i> significantly reduced the post-harvest quality of 'Munage' grapes, which was manifested by an increase in incidence and rot rate, a significant increase in weight loss rate and fruit color difference, and a significant decrease in fruit firmness. In addition, <i>B. cinerea</i> infection significantly changed the reactive oxygen species and antioxidant enzyme activities of 'Munage' grapes, including increasing the H₂O₂ content and O₂^- generation rate as well as changing the superoxide dismutase (SOD), glutathione (GSH), catalase (CAT), and peroxidase (POD) activities. <i>B. cinerea</i> also significantly changed the wax structure and content of 'Munage' grapes, causing the wax to completely dissolve and disappear and reducing the relative content of wax components. Through RNA-seq analysis, it was found that after <i>B. cinerea</i> infection, 49 differentially expressed genes (DEGs) related to fatty acid synthesis, extension, cutin and wax synthesis, and wax transport showed up-regulation or down-regulation, and 12 different transcription factors (TFs) also showed significant differential expression. These TFs were correlated with DEGs related to wax synthesis and metabolism, indicating that they may play an important role in the epidermal wax changes in 'Munage' grapes caused by <i>B. cinerea</i>. This study revealed the impact of <i>B. cinerea</i> on the post-harvest quality of 'Munage' grapes and their molecular mechanism and provided a scientific basis for grape disease prevention and quality maintenance.