GsCYP93D1, a Cytochrome P450 Gene from Wild Soybean, Mediates the Regulation of Plant Alkaline Tolerance and ABA Sensitivity

Cytochrome P450 enzymes (CYPs) are crucial catalysts responsible for the oxidative modification of diverse substrates, including plant hormones, antioxidants, and compounds involved in abiotic stress responses. While CYP functions in drought and salt stress adaptation have been extensively studied, their contribution to alkaline stress tolerance, particularly concerning specific cytochrome P450 genes in wild soybean (Glycine soja), remains less explored. In this study, a cytochrome P450 gene, GsCYP93D1, was identified and isolated, and its regulatory role under alkaline stress was elucidated. Transgenic GsCYP93D1 increased Arabidopsis and soybean hairy root resistance to alkaline stress, but the Arabidopsis atcyp93d1 mutant showed a reduced capacity for alkaline tolerance. Subsequent investigation showed the enhanced antioxidant defense capabilities of GsCYP93D1 transgenic plants, as evidenced by reduced superoxide radical (O2−) production under exposure to alkaline stress. Furthermore, compared to the atcyp93d1 mutant, transgenic lines of GsCYP93D1 showed sensitivity to ABA. Moreover, transcript levels of genes associated with alkaline stress response and ABA signaling pathways were elevated in both GsCYP93D1 transgenic and mutant lines. Collectively, our findings demonstrate that GsCYP93D1 positively modulates plant tolerance to alkaline stress and enhances ABA sensitivity.