四川农业大学陈学伟等研究人员合作发现，水稻转录因子bHLH25通过感知H₂O₂赋予对多种疾病的抗性。这一研究成果于2025年1月14日在线发表在国际学术期刊《细胞研究》上。

研究人员报告了水稻基础/螺旋环螺旋（bHLH）转录因子bHLH25如何直接感知过氧化氢（H₂O₂），从而赋予水稻对由真菌或细菌引起的多种疾病的抗性。在病原攻击下，水稻植物增加了H₂O₂的产生，H₂O₂直接氧化位于细胞核中bHLH25的第256位蛋氨酸（Met256）。氧化后的bHLH25抑制miR397b的表达，激活木质素生物合成以增强植物细胞壁的强度，从而阻止病原体侵入植物细胞。木质素生物合成消耗H₂O₂，导致非氧化的bHLH25积累。

非氧化的bHLH25则促进反转，增强二萜合成酶2（CPS2）的表达，进而增加植物抗生素的生物合成，抑制逃逸入植物的病原体扩展。bHLH25的氧化/非氧化状态变化使植物能够维持H₂O₂、木质素和植物抗生素在最佳水平，从而有效抵御病原体侵袭，并防止这三种分子过度积累而对植物造成损害。

因此，该发现揭示了一种新机制，通过该机制单一蛋白质促进两条独立的防御通路对抗病原体。值得注意的是，来自现有植物基因组的bHLH25同源基因都包含一个保守的M256-like蛋氨酸，表明这一机制在植物界的广泛存在。此外，这一Met-氧化机制也可能被其他真核生物转录因子用来感知H₂O₂并改变其功能。

据悉，H₂O₂是一种普遍存在的信号分子，调控着包括先天免疫在内的许多生物过程，广泛存在于所有真核生物中。然而，目前关于转录因子如何在真核生物中直接感知H₂O₂的机制仍不完全清楚。

附：英文原文

Title: Rice transcription factor bHLH25 confers resistance to multiple diseases by sensing H2O2

Author: Liao, Haicheng, Fang, Yu, Yin, Junjie, He, Min, Wei, Yingjie, Zhang, Juan, Yong, Shuang, Cha, Jiankui, Song, Li, Zhu, Xiaobo, Chen, Xixi, Kov, Jn, Hou, Qingqing, Ma, Zhaotang, Zhou, Xiaogang, Chen, Lin, Yumoto, Emi, Yang, Tian, He, Qi, Li, Wei, Deng, Yixin, Li, Haoxuan, Li, Mingwu, Qing, Hai, Zou, Lijuan, Bi, Yu, Liu, Jiali, Yang, Yihua, Ye, Daihua, Tao, Qi, Wang, Long, Xiong, Qing, Lu, Xiang, Tang, Yongyan, Li, Ting, Ma, Bingtian, Qin, Peng, Li, Yan, Wang, Wenming, Qian, Yangwen, urkovi, Jaroslav, Miyamoto, Koji, Chern, Mawsheng, Li, Shigui, Li, Weitao, Wang, Jing, Chen, Xuewei

Issue&Volume: 2025-01-14

Abstract: Hydrogen peroxide (H2O2) is a ubiquitous signal regulating many biological processes, including innate immunity, in all eukaryotes. However, it remains largely unknown that how transcription factors directly sense H2O2 in eukaryotes. Here, we report that rice basic/helix-loop-helix transcription factor bHLH25 directly senses H2O2 to confer resistance to multiple diseases caused by fungi or bacteria. Upon pathogen attack, rice plants increase the production of H2O2, which directly oxidizes bHLH25 at methionine 256 in the nucleus. Oxidized bHLH25 represses miR397b expression to activate lignin biosynthesis for plant cell wall reinforcement, preventing pathogens from penetrating plant cells. Lignin biosynthesis consumes H2O2 causing accumulation of non-oxidized bHLH25. Non-oxidized bHLH25 switches to promote the expression of Copalyl Diphosphate Synthase 2 (CPS2), which increases phytoalexin biosynthesis to inhibit expansion of pathogens that escape into plants. This oxidization/non-oxidation status change of bHLH25 allows plants to maintain H2O2, lignin and phytoalexin at optimized levels to effectively fight against pathogens and prevents these three molecules from over-accumulation that harms plants. Thus, our discovery reveals a novel mechanism by which a single protein promotes two independent defense pathways against pathogens. Importantly, the bHLH25 orthologues from available plant genomes all contain a conserved M256-like methionine suggesting the broad existence of this mechanism in the plant kingdom. Moreover, this Met-oxidation mechanism may also be employed by other eukaryotic transcription factors to sense H2O2 to change functions.

DOI: 10.1038/s41422-024-01058-4

Source: https://www.nature.com/articles/s41422-024-01058-4