The StABI5-StCAT1 Module Regulates Potato Resistance to Early Blight Through the ROS Signaling Pathway

Potato early blight is a fungal disease caused by Alternaria solani that seriously affects potato production. Catalase (CAT), an important antioxidant enzyme in plants, regulates the basal immune response to necrotrophic pathogens by decomposing hydrogen peroxide (H₂O₂); however, its role in potato early blight remains unclear. The results revealed that using a H₂O₂ biosensor for transient overexpression in Nicotiana benthamiana, we found that A. solani infection significantly induced sustained H₂O₂ accumulation in tobacco leaves. Exogenous application of H₂O₂ to potato leaves followed by inoculation with A. solani showed that elevated H₂O₂ levels promoted infection by the pathogen. StCAT1 expression was upregulated upon A. solani infection. Silencing StCAT1 in potato reduced antioxidant enzyme activities (SOD, PAL, CAT) and disease resistance, accompanied by elevated H₂O₂ accumulation. Overexpression of StCAT1 enhanced antioxidant enzyme activities and disease resistance while decreasing H₂O₂ levels. Additionally, StABI5 was identified as an upstream transcription factor that activates StCAT1 expression, and silencing StABI5 compromised potato resistance to early blight. In conclusion, this study confirms that StCAT1 acts as a positive regulatory factor and mediates potato resistance to early blight through the StABI5-StCAT1 signaling pathway, providing scientific basis and genetic resources for disease-resistant breeding.