Hybrid rice, widely planted in Asia, is pathogen resistant and has superior yields, making it a major contributor to global food security. The two-line hybrid rice system, which utilizes mutants exhibiting photo-/thermo-sensitive genic male sterility (P/TGMS), is the leading hybrid rice breeding technology. Mutations in THERMO-SENSITIVE GENIC MALE STERILE 5 (TMS5) accounts for over 95% of current TGMS lines. We previously found that tms5 carries a mutation in ribonuclease Z^S1. Despite its importance for breeding robust rice lines, the mechanism underlying tms5-mediated TGMS remains elusive. Here, we demonstrate that TMS5 is a tRNA 2′,3′-cyclic phosphatase. The tms5 mutation leads to accumulation of 2′,3′-cyclic phosphate (cP)-ΔCCA-tRNAs (tRNAs without 3′ CCA ended with cP), which is exacerbated by high temperatures, and reduction in the abundance of mature tRNAs, particularly alanine tRNAs (tRNA-Alas). Overexpression of tRNA-Alas in the tms5 mutant restores male fertility to 70%. Remarkably, male fertility of tms5 mutant is completely restored at high temperatures by knocking out OsVms1 which encodes the enzyme for cP-ΔCCA-tRNA generation. Our study reveals the mechanism underlying tms5-mediated TGMS in rice and provides mechanistic insight into the further improvement of TGMS in hybrid crop development.

杂交稻在亚洲广泛种植，具有抗病原体性，产量高，是全球粮食安全的主要贡献者。双系杂交水稻系统利用表现出光敏/热敏基因雄性不育 （P/TGMS） 的突变体，是领先的杂交水稻育种技术。热敏基因男性无菌 5 （TMS5） 突变占当前 TGMS 系的 95% 以上。我们之前发现 tms5 在核糖核酸酶 Z^S1 中携带突变。尽管 tms 5 介导的 TGMS 对培育健壮的水稻品系很重要，但其机制仍然难以捉摸。在这里，我们证明 TMS5 是一种 tRNA 2'，3'-环磷酸酶。tms5 突变导致 2'，3'-环磷酸盐 （cP）-ΔCCA-tRNA（没有 3'-CCA 以 cP 结尾的 tRNA）的积累，高温加剧了这种情况，成熟 tRNA 的丰度降低，特别是丙氨酸 tRNA （tRNA-Alas）。tms5 突变体中 tRNA-Alas 的过表达可将雄性生育能力恢复到 70%。值得注意的是，tms5 突变体的雄性生育能力在高温下通过敲除编码 cP-ΔCCA-tRNA 生成酶的 OsVms1 完全恢复。我们的研究揭示了 TMS5 介导的水稻 TGMS 的潜在机制，并为 TGMS 在杂交作物发育中的进一步改进提供了机制见解。