State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangdong Laboratory for Lingnan Modern Agriculture, Key Laboratory for Enhancing Resource Use Efficiency of Crops in South China, Ministry of Agriculture and Rural Affairs, College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China.
College of Agriculture & Biology, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, China.
New Phytol. 2024 Mar;241(5):2059-2074. doi: 10.1111/nph.19520. Epub 2024 Jan 10.
Thermo-sensitive genic male sterile (TGMS) lines are the core of two-line hybrid rice (Oryza sativa). However, elevated or unstable critical sterility-inducing temperatures (CSITs) of TGMS lines are bottlenecks that restrict the development of two-line hybrid rice. However, the genes and molecular mechanisms controlling CSIT remain unknown. Here, we report the CRITICAL STERILITY-INDUCING TEMPERATURE 2 (CSIT2) that encodes a really interesting new gene (RING) type E3 ligase, controlling the CSIT of thermo-sensitive male sterility 5 (tms5)-based TGMS lines through ribosome-associated protein quality control (RQC). CSIT2 binds to the large and small ribosomal subunits and ubiquitinates 80S ribosomes for dissociation, and may also ubiquitinate misfolded proteins for degradation. Mutation of CSIT2 inhibits the possible damage to ubiquitin system and protein translation, which allows more proteins such as catalases to accumulate for anther development and inhibits abnormal accumulation of reactive oxygen species (ROS) and premature programmed cell death (PCD) in anthers, partly rescuing male sterility and raised the CSIT of tms5-based TGMS lines. These findings reveal a mechanism controlling CSIT and provide a strategy for solving the elevated or unstable CSITs of tms5-based TGMS lines in two-line hybrid rice.
温敏雄性不育（TGMS）系是两系杂交水稻（Oryza sativa）的核心。然而，TGMS 系临界不育诱导温度（CSIT）升高或不稳定是限制两系杂交水稻发展的瓶颈。然而，控制 CSIT 的基因和分子机制尚不清楚。在这里，我们报道了 CRITICAL STERILITY-INDUCING TEMPERATURE 2（CSIT2），它编码一个真的很有趣的新基因（RING）型 E3 连接酶，通过核糖体相关蛋白质量控制（RQC）控制基于热敏感雄性不育 5（tms5）的 TGMS 系的 CSIT。CSIT2 结合到大、小核糖体亚基上，并泛素化 80S 核糖体使其解离，也可能泛素化错误折叠的蛋白质进行降解。CSIT2 的突变抑制了可能对泛素系统和蛋白质翻译造成的损害，这使得更多的蛋白质如过氧化氢酶得以积累，从而促进花药发育，并抑制花药中活性氧（ROS）的异常积累和过早的程序性细胞死亡（PCD），部分挽救了雄性不育，并提高了基于 tms5 的 TGMS 系的 CSIT。这些发现揭示了控制 CSIT 的机制，并为解决两系杂交水稻中基于 tms5 的 TGMS 系 CSIT 升高或不稳定的问题提供了策略。
