BcSRC2 interacts with BcAPX4 to increase ascorbic acid content for responding ABA signaling and drought stress in pak choi.

As a reducing substance, ascorbic acid functioned well in abiotic and biotic stress. However, the regulatory mechanism of drought resistance is rarely known in pak choi. Here we found a gene containing a C2 domain that responds to ABA signal and drought regulation in pak choi. Silencing of reduces ascorbic acid content and drought resistance of pak choi. In , BcSRC2 overexpression promotes ascorbic acid accumulation and increases drought tolerance. Meanwhile, transcriptome analysis between WT and -overexpressing pak choi suggests that ascorbic acid-related genes are regulated. BcSRC2 interacts with BcAPX4 and inhibit APX activity and , increasing the ascorbic acid content. We also found that drought stress increases ABA content, which reduces the expression of BcMYB30. BcMYB30 bound to the promoter of and reduced its expression. Overall, our results suggest that a regulatory module, BcMYB30-BcSRC2-BcAPX4, plays a central role in increasing ascorbic acid content for responding ABA-mediated drought regulation in pak choi.