SmWRKY6 Mediates Thermo-Enhanced Resistance to Ralstonia solanacearum in Eggplant by Activating SmPR1b

Global climate warming has significantly increased plant diseases prevalence. In subtropical regions, high temperature frequently co-occurs with bacterial wilt caused by Ralstonia solanacearum, creating compound stress conditions that severely compromise eggplant productivity. However, the molecular mechanisms governing eggplant's response to combined heat and pathogen stress remain poorly characterized. In this study, we conducted the temperature analyses of Guangzhou, China, and isolated a thermotolerant strain PSS219-GZ under high temperatures in eggplant. Phenotypic analysis of eggplants inoculated with PSS219-GZ at different temperature, indicated that PSS219-GZ have maximal pathogenicity at 37°C. SmWRKY6 is a WRKY transcription factor activated by both high temperatures and Ralstonia solanacearum infection. Genetic evidence from silencing of SmWRKY6 via VIGS in eggplants and overexpression of SmWRKY6 in tomato demonstrated that SmWRKY6 is essential for enhancing resistance to Ralstonia solanacearum under high-temperature stress. SmWRKY6 directly binds to and transcriptionally activates the SmPR1b promoter, forming a key regulatory node in bacterial wilt resistance pathways. This study provides novel insights into plant responses to combined heat and R. solanacearum stress and highlights potential resistance genes for mitigating compound stress effects.