Abstract

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.

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