Arabidopsis TRB Proteins Promote ROS Detoxification for Ethanol-Enhanced Salt Stress Tolerance

Soil salinization is a major threat to global agricultural productivity. Developing strategies to alleviate the effects of soil salinization is essential for maintaining stable and sustainable food production under climate change conditions. We previously showed that ethanol enhances Arabidopsis salt stress tolerance by promoting reactive oxygen species (ROS) detoxification through ASCORBATE PEROXIDASE (AtAPX1/2) activation. However, ethanol induces the expression of many genes beyond AtAPX1/2. Moreover, the transcriptional mechanisms underlying ethanol-mediated stress tolerance remain unclear. In this study, we identified TELOMERE REPEAT BINDING (TRB) proteins as regulators of ethanol-enhanced salt stress tolerance. Transcriptome and qRT-PCR analyses showed that TRBs regulate the expression of AtCSD1, AtCSD2, and AtCCS, which encode Cu/ZnSODs and a copper chaperone. Ethanol increased Cu/ZnSOD activity, whereas csd1 and ccs mutants were sensitive to salt stress and accumulated superoxide, even after ethanol treatment. Thus, Cu/ZnSOD-mediated detoxification contributes to ethanol-induced stress tolerance. ChIP assays showed that AtTRB3 associates with AtCSD1, AtCSD2, and AtCCS, and that ethanol treatment enhanced H4K5 acetylation at these loci. Ethanol also increased global H4 acetylation levels, suggesting that ethanol metabolism may contribute to histone acetylation. Accordingly, AtTRB proteins likely promote Cu/ZnSOD-dependent ROS detoxification through chromatin-associated gene activation, thereby contributing to ethanol-mediated salinity tolerance in Arabidopsis seedlings.