The RsWRKY18-RsHSFA2 module confers thermotolerance by activating RsHSP22 during taproot thickening in radish

作者：Jingxue Li, Feng Cui, Yan Wang, Xiaoli Zhang, Liang Xu, Kai Wang, Xiaoqi Yuan, Yi Mei, Jiali Ying, Ruixuan Wang, Wenrong Liu, Liwang Liu · 发表于：PLANT PHYSIOLOGY · 年份：2026 · DOI：10.1093/plphys/kiag007 · 被引用次数：1 · 研究领域：Plant Gene Expression Analysis、Polysaccharides and Plant Cell Walls、Plant Molecular Biology Research

Radish (Raphanus sativus L.) is a cool-season root vegetable crop grown worldwide. Heat stress (HS) severely restricts radish taproot formation, resulting in the loss of yield and quality. However, the regulatory mechanism underlying radish taproot thickness under HS conditions has been largely unexplored. Here, we identified a heat-induced HSP protein, HEAT SHOCK PROTEIN 22 (RsHSP22), via comparative proteome analysis. Yeast one-hybrid (Y1H) assays, dual-luciferase reporter assays, and electrophoretic mobility shift assays demonstrated that WRKY DNA-BINDING PROTEIN 18 (RsWRKY18) and HEAT STRESS TRANSCRIPTION FACTOR A2 (RsHSFA2) bind to the W-box and HSE element of the promoter of RsHSP22 to activate its expression, respectively. RsWRKY18 and RsHSFA2 are heat-inducible and nucleus-localized transcription activators, and their expression levels in the heat-tolerant genotype "NAU-XBC" were higher compared to the heat-susceptible genotype "NAU-YB" after a short- or long-term HS treatment at the taproot thickening stage. Overexpression of RsWRKY18 and RsHSFA2 alleviated oxidative damage under HS and conferred heat tolerance in Arabidopsis (Arabidopsis thaliana) and radish, whereas silencing RsWRKY18 resulted in heat susceptibility and limited taproot thickening in radish. Furthermore, RsWRKY18 bound to the promoters of several taproot thickening-related genes, including Xyloglucan endotransglucosylase/hydrolase 32 (RsXTH32), Alpha-expansin 9 (RsEXPA9), KNOTTED-like from Arabidops...