The potato StTBP4 - StLOX2 cascade compromises resistance to Alternaria solani by suppressing the jasmonic acid biosynthesis pathway

Abstract

Potato early blight, caused by Alternaria solani, poses a significant threat to global potato yield. While telomere-binding proteins (TBPs) are known to play critical roles in plant growth and development, their roles in potato responses to early blight remain unclear. Here, we report that StTBP4 compromises potato resistance to A. solani by suppressing the transcription of StLOX2, a key gene in the jasmonic acid (JA) biosynthetic pathway. StTBP4 expression was significantly induced upon A. solani infection. Functional characterization of StTBP4-silenced (TRV:StTBP4) in potato and tobacco knockout lines (CR-nttbp4) demonstrated enhanced disease resistance, whereas tobacco transgenic overexpression lines (StTBP4-OE) exhibited increased susceptibility. Physiological assays indicated that StTBP4 modulates resistance primarily by dampening JA accumulation; although abscisic acid (ABA) levels were also altered, exogenous hormone and inhibitor treatments confirmed that the resistance phenotype depended on JA rather than ABA. Mechanistically, StTBP4 binds directly to the StLOX2 promoter to repress its transcription, thereby blocking the downstream JA-mediated reactive oxygen species (ROS) burst and pattern-triggered immunity (PTI). Collectively, our findings elucidate a molecular mechanism by which the StTBP4-StLOX2 module compromises plant immunity, highlighting StTBP4 as a potential target for engineering early blight resistance in potato.