The Potato StNAC2-StSABP2 Module Enhanced Resistance to Phytophthora infestans Through Activating the Salicylic Acid Pathway

Potato late blight is an important disease in potato production, which causes serious damage. Salicylic acid (SA) is a plant hormone involved in the regulation of potato (Solanum tuberosum) resistance to Phytophthora infestans. In this study, it was found that exogenous methyl salicylate (MeSA) treatment could significantly enhance the resistance of potato to P. infestans. RNA-seq results confirmed that SA was important for potato resistance to P. infestans. Salicylic acid binding protein 2 (SABP2) is a member of alpha/beta hydrolase family, which can convert MeSA into SA to regulate the steady state of SA in plants. StSABP2 protein was obtained through prokaryotic expression, and enzymatic analysis in vitro confirmed that StSABP2 could transform MeSA into SA. In order to explore the function of StSABP2 in the process of plant resistance to P. infestans, we carried out virus-mediated gene silencing of StSABP2 in potato and transiently expressed StSABP2 in tobacco. The results showed that StSABP2 positively regulated plant resistance to P. infestans, and this process was achieved by mediating the transcription of SA signal and defence-related genes. Then we screened for the upstream regulator of StSABP2. The results of double luciferase and yeast one-hybrid analysis showed that StNAC2 could activate the transcription of StSABP2. The StNAC2-StSABP2 module regulated potato resistance to P. infestans by positively mediating the SA pathway. This study provides a new idea for improving host resistance to potato late blight by regulating the SA signal in potato and provides germplasm resources for potato resistance breeding.