Ju Lili, Yang Shanshan, Liang Xiaoyan, Zhang Zhiheng, Wang Hao, Qin Tong, Li Fayu, Huang Jingjing, Chen Dong, Zheng Dehong, Wang Peng, Zhao Jianlong, He Yongqiang, Yu Wenjin, Zhang Xiaoxiao
Guangxi Key Laboratory of Agro-environment and Agro-product Safety, College of Agriculture, Guangxi University, Nanning 530004, China.
State Key Laboratory of Vegetable Biobreeding, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Int J Biol Macromol. 2025 Jul;318(Pt 2):144718. doi: 10.1016/j.ijbiomac.2025.144718. Epub 2025 Jun 2.
The type III effector RipH1, a conserved virulence factor in Ralstonia solanacearum, manipulates plant immunity by targeting the transcription factor B-box (BBX)-containing protein 31, AtBBX31 in Arabidopsis thaliana. Here, we demonstrate that RipH1 suppresses reactive oxygen species (ROS) production and triggers programmed cell death (PCD) in multiple plant species, including Nicotiana benthamiana, tomato, and Arabidopsis thaliana. Notably, RipH1 negatively regulates the pathogenicity of R. solanacearum GMI1000 in A. thaliana but not in tomato, suggesting host-specific virulence modulation. Yeast two-hybrid, bimolecular fluorescence complementation, and co-immunoprecipitation assays confirm the direct interaction between RipH1 and AtBBX31. This interaction stabilizes both proteins and promotes AtBBX31 membrane localization, independent of the ubiquitination pathway. Notably, AtBBX31 positively regulates resistance to R. solanacearum and ROS production, and RipH1 disrupts its binding to the promoter of AtBBX29, which positively regulates resistance to R. solanacearum and ROS production. By targeting AtBBX31, RipH1 impairs the immune signaling of the AtBBX31-AtBBX29 axis. This study reveals a novel mechanism by which bacterial effectors hijack plant transcription factors to reprogram immunity pathways. The findings highlight the importance of biological macromolecules in plant-pathogen interactions and provide insights for developing durable resistance strategies against bacterial wilt.
III型效应蛋白RipH1是青枯雷尔氏菌中一种保守的毒力因子，它通过靶向拟南芥中含转录因子B-box（BBX）的蛋白31即AtBBX31来操纵植物免疫。在此，我们证明RipH1抑制多种植物物种（包括本氏烟草、番茄和拟南芥）中活性氧（ROS）的产生并触发程序性细胞死亡（PCD）。值得注意的是，RipH1负向调节青枯雷尔氏菌GMI1000在拟南芥中的致病性，但在番茄中却并非如此，这表明存在宿主特异性的毒力调节。酵母双杂交、双分子荧光互补和免疫共沉淀试验证实了RipH1与AtBBX31之间的直接相互作用。这种相互作用使两种蛋白都稳定，并促进AtBBX31的膜定位，且不依赖泛素化途径。值得注意的是，AtBBX31正向调节对青枯雷尔氏菌的抗性和ROS的产生，而RipH1破坏了它与AtBBX29启动子的结合，AtBBX29正向调节对青枯雷尔氏菌的抗性和ROS的产生。通过靶向AtBBX31，RipH1损害了AtBBX31-AtBBX29轴的免疫信号传导。本研究揭示了一种细菌效应蛋白劫持植物转录因子以重新编程免疫途径新机制。这些发现突出了生物大分子在植物-病原体相互作用中的重要性，并为制定针对青枯病的持久抗性策略提供了见解。
