Negative Regulatory Role of Non-Coding RNA Vvi-miR3633a in Grapevine Leaves and Callus under Heat Stress

The grapevine, a globally significant fruit and an essential fruit tree species in China, is vulnerable to the adverse effects of high temperatures. Understanding the roles of microRNA and transcription factors in plant development and stress resistance is crucial for mitigating the impact of high temperature on grape growth and yield. This study investigates the response of miRNA to high-temperature stress in grape leaves. The expression level of Vvi-miR3633a was found to be inhibited under heat treatment in both Thompson seedless and Shen yue varieties, while its potential target genes (Vv-Atg36 and Vv-GA3ox2) were induced. Through transgenic overexpression experiments, it was demonstrated that Vvi-miR3633a plays a role in thermal response by affecting the expression of target genes. Furthermore, under heat stress conditions, overexpression of Vvi-miR3633a in grape callus decreased heat resistance compared to the control group (CK). The study also revealed that the target genes of Vvi-miR3633a regulate the expression of oxidase synthesis genes VvSOD and VvCAT, leading to reduced oxidase synthesis which may compromise the oxidation system. Additionally, the expression level of heat shock proteins in the transgenic lines was changed compared to the control (CK). Overall, this research provides valuable insights into understanding the molecular mechanisms involved in different crossing/breeding programs to produce heat-resistant grape varieties. Such varieties can be appropriate to propagate in warm climate areas with high temperature conditions.