Humidity-sensitive genic male sterility (HGMS) is a novel type of environment-sensitive male sterility (EGMS) which plants are male sterile at low humidity and male fertile at high humidity. Previous studies have revealed that OsCER1 contributes to very-long-chain (VLC) alkanes biosynthesis in rice (Oryza sativa L.). Here, applying the CRISPR/Cas9 technique, we obtained two independent OsCER1 knockout lines (OsCER1Cas). Both OsCER1Cas lines exhibited HGMS. Mutant pollen showed defects in adhesion and germination on stigmas at low humidity, whereas high humidity enhanced the pollen germination rate. Transmission electron microscopy (TEM) observations of mutant pollen revealed abnormal tryphine structure, potentially representing the basis of HGMS. Furthermore, co-pollination with mixed OsCER1Cas mutant and maize (Zea mays L.) pollen could rescue the fertility of the mutant, thereby establishing the key role of tryphine in germination on stigmas. OsCER1 knockout might affect VLC alkane metabolism and therefore alter the lipid composition of tryphine. It could lead to the defects in pollen grain adhesion, hydration and germination, resulting in HGMS. This work identified the mechanism of HGMS induced by VLC alkanes in rice and the generality of tryphine in different species of Gramineae.

湿度敏感型雄性不育（HGMS）是一种新型的环境敏感型雄性不育（EGMS），其植物在低湿度下为雄性不育，在高湿度下为雄性可育。先前的研究表明，OsCER1有助于水稻（Oryza sativa L.）的超长链（VLC）烷烃生物合成。在这里，应用CRISPR / Cas9技术，我们获得了两条独立的OsCER1基因敲除品系（OsCER1 Cas）。两者均为OsCER1Cas系表现出HGMS。突变的花粉在低湿度下显示在柱头上的附着力和发芽缺陷，而高湿度提高了花粉的发芽率。突变体花粉的透射电子显微镜（TEM）观察显示异常的胰啡肽结构，可能代表了HGMS的基础。此外，混合OsCER1 Cas突变体与玉米（玉米（Zea mays L.）花粉）的联合授粉可以挽救该突变体的繁殖力，从而建立了色胺在柱头萌发中的关键作用。OsCER1敲除可能会影响VLC烷烃的代谢，因此会改变Tryphine的脂质组成。它可能导致花粉粒粘附，水合作用和发芽的缺陷，从而导致HGMS。这项工作确定了稻米中VLC烷烃诱导HGMS的机制以及不同禾本科中胰蛋白酶的普遍性。