A Killer-Protector System Regulates Both Hybrid Sterility and Segregation Distortion in Rice
A Killer-Protector System Regulates Both Hybrid Sterility and Segregation Distortion in Rice
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杀手-保护系统调节水稻杂交不育和分离扭曲
DOI：
10.1126/science.1223702
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发表时间：
2012-09-14
期刊：
影响因子：
56.9
通讯作者：
Zhang, Qifa
中科院分区：
文献类型：
--
作者：
Yang, Jiangyi;Zhao, Xiaobo;Zhang, Qifa
水稻品种间的杂交不育现象长期以来一直是一个难题，它阻碍了作物性能和产量性状的改良。Yang等人（第1336页）已经确定了三个相互关联的基因，分别编码杀手蛋白、伴侣蛋白和保护蛋白。杀手和伴侣共同杀死不携带功能保护器的雌性配子，导致携带功能保护器的配子优先传递，这也导致了后代的隔离扭曲。这一解释解释了水稻物种之间以及其他生物之间如何保持生殖隔离，也为通过亚种间杂种优势提高产量提供了途径。一个包含三个蛋白质编码基因的遗传位点是水稻杂交不育系统的基础。杂种不育是合子后生殖隔离的一种主要形式，它限制了种群间的基因流动。栽培水稻（Oryza sativa L.）由籼稻和粳稻两个亚种组成；亚种间杂交通常是不育的。研究表明，在S5位点上，一个由三个紧密相连的基因[开放阅读框3 （ORF3）到ORF5]编码的杀伤-保护系统调节了籼粳杂交种的育性。在雌性孢子发生过程中，ORF5+（杀手）和ORF4+（伴侣）的作用引起内质网（ER）应激。ORF3+（保护者）可以阻止内质网应激，产生正常配子，而ORF3 -不能阻止内质网应激，导致细胞程序性过早死亡，导致胚囊流产。ORF3+配子的优先传递导致了后代的分离扭曲。这些结果增加了我们对籼稻和粳稻之间差异的理解，并可能有助于水稻遗传改良。
Conquering Rice Sterility The hybrid sterility occurring among rice species has long been a puzzle and hampers progress in breeding crops with improved performance and yield characteristics. Yang et al. (p. 1336) have identified three linked genes encoding a killer, a partner, and a protector protein. The killer and partner work together to kill female gametes not carrying the functional protector, resulting in preferential transmission of gametes carrying the functional protector, which also causes segregation distortion in the progeny. This explanation for how reproductive isolation is maintained among species of rice, and perhaps other organisms, also offers approaches for boosting yields by intersubspecific heterosis. A genetic locus containing three protein-coding genes underlies the system causing hybrid sterility among rice species. 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.