MdWRKY31 ‐ MdNAC7 regulatory network: orchestrating fruit softening by modulating cell wall‐modifying enzyme MdXTH2 in response to ethylene signalling

作者：Jia‐Hui Wang, Quan Sun, Chang‐Ning Ma, Meng‐Meng Wei, Chukun Wang, Yuwen Zhao, Wenyan Wang, Da‐Gang Hu · 发表于：Plant Biotechnology Journal · 年份：2024 · DOI：10.1111/pbi.14445 · 被引用次数：62 · 研究领域：Postharvest Quality and Shelf Life Management、Polysaccharides and Plant Cell Walls、Plant Physiology and Cultivation Studies

Softening in fruit adversely impacts their edible quality and commercial value, leading to substantial economic losses during fruit ripening, long-term storage, long-distance transportation, and marketing. As the apple fruit demonstrates climacteric respiration, its firmness decreases with increasing ethylene release rate during fruit ripening and postharvest storage. However, the molecular mechanisms underlying ethylene-mediated regulation of fruit softening in apple remain poorly understood. In this study, we identified a WRKY transcription factor (TF) MdWRKY31, which is repressed by ethylene treatment. Using transgenic approaches, we found that overexpression of MdWRKY31 delays softening by negatively regulating xyloglucan endotransglucosylase/hydrolases 2 (MdXTH2) expression. Yeast one-hybrid (Y1H), electrophoretic mobility shift (EMSA), and dual-luciferase assays further suggested that MdWRKY31 directly binds to the MdXTH2 promoter via a W-box element and represses its transcription. Transient overexpression of ethylene-induced MdNAC7, a NAC TF, in apple fruit promoted softening by decreasing cellulose content and increasing water-soluble pectin content in fruit. MdNAC7 interacted with MdWRKY31 to form a protein complex, and their interaction decreased the transcriptional repression of MdWRKY31 on MdXTH2. Furthermore, MdNAC7 does not directly regulate MdXTH2 expression, but the protein complex formed with MdWRKY31 hinders MdWRKY31 from binding to the promoter of MdXTH2. ...