National Key Laboratory for Rice Biology and Breeding, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China.
Ministry of Agriculture Key Laboratory of Molecular Biology of Crop Pathogens and Insect Pests, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China.
J Integr Plant Biol. 2024 Jul;66(7):1459-1480. doi: 10.1111/jipb.13666. Epub 2024 Apr 17.
Ubiquitination-mediated protein degradation is integral to plant immunity, with E3 ubiquitin ligases acting as key factors in this process. Here, we report the functions of OsATL32, a plasma membrane-localized Arabidopsis Tóxicos En Levadura (ATL)-type E3 ubiquitin ligase, in rice (Oryza sativa) immunity and its associated regulatory network. We found that the expression of OsATL32 is downregulated in both compatible and incompatible interactions between rice and the rice blast fungus Magnaporthe oryzae. The OsATL32 protein level declines in response to infection by a compatible M. oryzae strain or to chitin treatment. OsATL32 negatively regulates rice resistance to blast and bacterial leaf blight diseases, as well as chitin-triggered immunity. Biochemical and genetic studies revealed that OsATL32 suppresses pathogen-induced reactive oxygen species (ROS) accumulation by mediating ubiquitination and degradation of the ROS-producing OsRac5-OsRbohB module, which enhances rice immunity against M. oryzae. The protein phosphatase PHOSPHATASE AND TENSIN HOMOLOG enhances rice blast resistance by dephosphorylating OsATL32 and promoting its degradation, preventing its negative effect on rice immunity. This study provides insights into the molecular mechanism by which the E3 ligase OsATL32 targets a ROS-producing module to undermine rice immunity.
泛素化介导的蛋白质降解是植物免疫的重要组成部分，E3 泛素连接酶在此过程中起着关键作用。在这里，我们报告了质膜定位的拟南芥 Tóxicos En Levadura (ATL)型 E3 泛素连接酶 OsATL32 在水稻（Oryza sativa）免疫及其相关调控网络中的功能。我们发现，OsATL32 的表达在水稻与稻瘟病菌 Magnaporthe oryzae 的亲和和非亲和互作中均下调。OsATL32 蛋白水平在受到亲和 M. oryzae 菌株感染或几丁质处理时下降。OsATL32 负调控水稻对稻瘟病和细菌性条斑病的抗性，以及几丁质触发的免疫。生化和遗传研究表明，OsATL32 通过介导活性氧（ROS）产生的 OsRac5-OsRbohB 模块的泛素化和降解来抑制病原体诱导的 ROS 积累，从而增强水稻对 M. oryzae 的免疫力。蛋白磷酸酶 PHOSPHATASE AND TENSIN HOMOLOG 通过去磷酸化 OsATL32 并促进其降解来增强水稻对稻瘟病的抗性，从而防止其对水稻免疫的负面影响。这项研究提供了对 E3 连接酶 OsATL32 靶向 ROS 产生模块以破坏水稻免疫的分子机制的深入了解。
