National Key Laboratory of Crop Genetic Improvement and National Centre of Plant Gene Research, Huazhong Agricultural University, Wuhan 430070, China.
Science. 2012 Sep 14;337(6100):1336-40. doi: 10.1126/science.1223702.
Hybrid sterility is a major form of postzygotic reproductive isolation that restricts gene flow between populations. Cultivated rice (Oryza sativa L.) consists of two subspecies, indica and japonica; inter-subspecific hybrids are usually sterile. We show that a killer-protector system at the S5 locus encoded by three tightly linked genes [Open Reading Frame 3 (ORF3) to ORF5] regulates fertility in indica-japonica hybrids. During female sporogenesis, the action of ORF5+ (killer) and ORF4+ (partner) causes endoplasmic reticulum (ER) stress. ORF3+ (protector) prevents ER stress and produces normal gametes, but ORF3- cannot prevent ER stress, resulting in premature programmed cell death and leads to embryo-sac abortion. Preferential transmission of ORF3+ gametes results in segregation distortion in the progeny. These results add to our understanding of differences between indica and japonica rice and may aid in rice genetic improvement.
杂种不育性是一种主要的合子后生殖隔离形式，限制了种群之间的基因流动。栽培稻（Oryza sativa L.）由两个亚种籼稻和粳稻组成；亚种间杂种通常不育。我们表明，由三个紧密连锁基因[开放阅读框 3（ORF3）到 ORF5]编码的 S5 座位上的杀伤-保护系统调控籼粳杂种的育性。在雌性孢原细胞发生过程中，ORF5+（杀伤）和 ORF4+（伙伴）的作用导致内质网（ER）应激。ORF3+（保护）防止 ER 应激并产生正常配子，但 ORF3-不能防止 ER 应激，导致过早的程序性细胞死亡，导致胚囊流产。ORF3+配子的优先传递导致后代的分离失真。这些结果增加了我们对籼稻和粳稻之间差异的理解，并可能有助于水稻的遗传改良。
