Transcription Factor StHRAV1 Negatively Regulates Thermotolerance by Modulating ROS Accumulation in Potato

High-temperature stress severely impacts potato production, yet the molecular mechanisms remain poorly understood. In this study, we identified a novel RAV family gene, StHRAV1, in potato, whose expression is significantly suppressed under high-temperature stress. Suppressing StHRAV1 expression enhances thermotolerance in potato. The B3 domain and the RLFGV motif collectively mediate the transcriptional activity of StHRAV1, which is essential for its role as a transcriptional repressor. StHRAV1 interference lines showed reduced ion leakage, lower ROS levels, improved antioxidant capacity, and higher plant vitality under heat stress. These changes, along with alterations in multiple oxidative stress pathways in the RNA-seq, suggest that StHRAV1 modulates ROS clearance to control thermotolerance. DAP-seq and dual-luciferase assays demonstrated its direct regulation of several antioxidant genes. Furthermore, heterologous overexpression of StHRAV1 negatively regulates thermotolerance by promoting ROS accumulation in Arabidopsis. These findings deepen our understanding of how RAV transcription factors regulate thermotolerance in plants.