GhTrxh2 enhances plant tolerance to drought stress by maintaining ROS homeostasis

As a major abiotic constraint, drought stress adversely affects cotton growth and fiber yield. In our study, GhTrxh2 was characterized and demonstrated a positive role in the drought stress response. Treatment with ABA and PEG resulted in a marked induction of GhTrxh2 transcript level. The heterologous expression of GhTrxh2 in yeast conferred an enhanced survival rate under drought conditions. Silencing of GhTrxh2 in cotton decreased the activities of antioxidant enzymes and increased contents of MDA and H₂O₂, which regulated the accumulation of reactive oxygen species. The transcript levels of GhP5CS, GhDREB2A, GhCOR47, GhRAD29 decreased in silenced cotton. Conversely, overexpression of GhTrxh2 enhanced Arabidopsis tolerance to drought treatment. Transgenic Arabidopsis showed higher seed germination rate and root length, while accumulated less relative oxygen species during drought stress. Based on yeast one-hybrid and dual-luciferase assay, GhVIP1 directly bound to the promoter of GhTrxh2 and promoted GhTrxh2 expression. Yeast two-hybrid and luciferase complementation imaging (LCI) experiment confirmed a physical interaction between GhTrxh2 and GhPLA1. Collectively, these findings suggested that GhTrxh2 appeared to play an important role in plant drought tolerance by preventing ROS accumulation and regulating the expression of drought-related genes, which supplied important insights to drought tolerance mechanisms in cotton.