Environment‐sensitive male sterility (EGMS) lines are widely used in two‐line hybrid breeding in rice (Oryza sativa). At present, photoperiod‐sensitive genic male sterility (PGMS) lines and thermo‐sensitive genic male sterility (TGMS) lines are predominantly used in two‐line hybrid rice, with humidity‐sensitive genic male sterility (HGMS) lines rarely being reported.
Here, we showed that HUMIDITY‐SENSITIVE GENIC MALE STERILITY 1 (HMS1), encoding a β‐ketoacyl‐CoA synthase, plays key roles in the biosynthesis of very‐long‐chain fatty acids (VLCFAs) and HGMS in rice.
The hms1 mutant displayed decreased seed setting at low‐humidity, but normal seed setting at high‐humidity. HMS1 catalyzed the biosynthesis of the C26 and C28 VLCFAs, contributing to the formation of bacula and tryphine in the pollen wall, which protect the pollen from dehydration. Under low‐humidity, hms1 pollen showed poor adhesion and reduced germination on the stigmas, which could be rescued by increasing humidity. HMS1‐INTERACTING PROTEIN (HMS1I) interacted with HMS1 to co‐regulate HGMS. Furthermore, both japonica and indica rice varieties with defective HMS1 exhibited HGMS, suggesting that hms1 could potentially be used in hybrid breeding.
Our results reveal the novel mechanism of VLCFA‐mediated pollen wall formation, which protects pollen from low‐humidity stress in rice, and has a potential use in hybrid crop breeding.
該研究鑒定了一種新型的水稻溫度敏感型雄性不育突變體hms1(HUMIDITY-SENSITIVE GENIC MALE STERILITY 1 )。該突變體在低濕度環(huán)境中表現(xiàn)為雄性不育，而在高濕度環(huán)境下則完全可育。突變體中 C26:0 和 C28:0 超長鏈脂肪酸含量降低，花粉壁不能正常形成，導(dǎo)致在低濕度條件下花粉失水過快，花粉在柱頭上不能正常萌發(fā)。圖位克隆表明， HMS1編碼一個(gè)β-酮脂酰輔酶A合酶 (β-ketoacyl-CoA synthase, KCS)。該研究還發(fā)現(xiàn)了HMS1的輔助因子HMS1I (HMS1-INTERACTING PROTEIN)。hms1i突變體的表型與hms1的表型相似。該研究進(jìn)一步發(fā)現(xiàn)，粳稻和秈稻水稻品種中HMS1的突變均導(dǎo)致濕度敏感型雄性不育。因此，該研究揭示了一種濕度敏感型水稻雄性不育材料，在雜交育種中具有一定的應(yīng)用潛力。