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.