The CANNOT RESPOND TO DMBQ 1–GLUTAREDOXIN C1 module regulates Arabidopsis root growth via quinone-induced oxidation

Quinones are secondary metabolites widely produced by plants. They are sensed by the leucine-rich receptor kinase CANNOT RESPOND TO DMBQ 1 (CARD1) and play important roles in immunity and growth in nonparasitic plants. Quinone perception typically involves the posttranslational modification of proteins, particularly through cysteine oxidation. However, the relationship between quinone-induced cysteine modifications and the quinone–CARD1 signaling pathway remains unclear. Here, we performed a redox proteomics analysis to determine the extent of CARD1-mediated cysteine oxidation of proteins in Arabidopsis (Arabidopsis thaliana) seedlings following treatment with a quinone, 2,6-dimethoxy-1,4-benzoquinone (DMBQ). We found that GLUTAREDOXIN C1 (GRXC1) is a substrate protein of CARD1, whose oxidation is induced by DMBQ treatment. GRXC1 interacts with and is phosphorylated by CARD1, mediating Arabidopsis primary root growth. This work provides a molecular basis for understanding the DMBQ-induced redox signaling pathway and the DMBQ–CARD1–GRXC1 signaling pathway in response to redox alterations in Arabidopsis.