GhSTH-2 Integrates Host Redox Signalling and Effector Recognition and Confers Resistance Against Verticillium dahliae...

PR10/Bet v1-like proteins are key mediators of plant defence responses against microbial pathogens. Verticillium wilt, caused by the soil-borne fungus Verticillium dahliae, represents a major threat to global cotton production, yet the functions of PR10/Bet v1-like proteins in cotton resistance to this disease remain poorly understood. In this study, we characterise GhSTH-2, a PR10/Bet v1-like protein family in cotton, which is strongly upregulated at early stages of V. dahliae infection. Our results demonstrated that GhSTH-2 acts as a positive regulator of Verticillium wilt resistance and directly interacts with both the V. dahliae effector protein VdEPG1 and the redox-related protein GhTXNDC9. Silencing of GhSTH-2 in cotton compromised disease resistance, reduced reactive oxygen species (ROS) bursts, impaired lignin deposition, and downregulated the expression of ROS-producing genes. Conversely, overexpression of GhSTH-2 enhanced ROS production and disease resistance in Arabidopsis thaliana. Notably, ROS production was reduced in ΔVdEPG1-infected plants, accompanied by downregulated expression of GhSTH-2 and GhTXNDC9, and VdEPG1 was found to suppress GhSTH-2-triggered programmed cell death (PCD) and ROS accumulation. Collectively, these results suggest that GhSTH-2 contributes to cotton immunity by modulating ROS signalling through molecular associations with GhTXNDC9 and VdEPG1, highlighting its potential as a genetic target for enhancing Verticillium wilt resistance.