National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research Shanghai, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai 200032, China.
Mol Plant. 2013 May;6(3):716-28. doi: 10.1093/mp/sss146. Epub 2012 Dec 8.
Hybrid weakness is an important reproductive barrier that hinders genetic exchange between different species at the post-zygotic stage. However, our understanding of the molecular mechanisms underlying hybrid weakness is limited. In this study, we report discovery of a novel interspecific hybrid weakness in a rice chromosome segment substitution line (CSSL) library derived from a cross between the indica variety Teqing (Oryza sativa) and common wild rice (O. rufipogon). The dominant Hybrid weakness i1 (Hwi1) gene from wild rice is genetically incompatible with Teqing and induced a set of weakness symptoms, including growth suppression, yield decrease, impaired nutrient absorption, and the retardation of crown root initiation. Phytohormone treatment showed that salicylic acid (SA) could restore the height of plants expressing hybrid weakness, while other phytohormones appear to have little effect. Fine mapping indicated that Hwi1 is located in a tandem leucine-rich repeat receptor-like kinase (LRR-RLK) gene cluster. Within the 13.2-kb candidate region on the short arm of chromosome 11, there are two annotated LRR-RLK genes, LOC_Os11g07230 and LOC_Os11g07240. The Teqing allele of LOC_Os11g07230 and the wild rice allele of LOC_Os11g07240 encode predicted functional proteins. Based on the genetic inheritance of hybrid weakness, LOC_Os11g07240 is implicated as the candidate gene for Hwi1. Functional analysis of Hwi1 will expand our knowledge of the regulation of hybrid weakness in rice.
杂种弱势是一种重要的生殖障碍，它阻碍了不同物种在合子后阶段的遗传交换。然而，我们对杂种弱势背后的分子机制的理解是有限的。在这项研究中，我们报告了在一个由籼稻品种特青（Oryza sativa）和普通野生稻（O. rufipogon）杂交衍生的水稻染色体片段代换系（CSSL）文库中发现的一种新的种间杂种弱势。野生稻的显性杂种弱势 i1（Hwi1）基因与特青在遗传上不兼容，并诱导了一系列弱势症状，包括生长抑制、产量下降、营养吸收受损和冠根起始延迟。植物激素处理表明，水杨酸（SA）可以恢复表达杂种弱势的植株的高度，而其他植物激素似乎影响不大。精细定位表明，Hwi1 位于串联富含亮氨酸重复受体样激酶（LRR-RLK）基因簇中。在第 11 号染色体短臂上的 13.2-kb 候选区域内，有两个注释的 LRR-RLK 基因，LOC_Os11g07230 和 LOC_Os11g07240。LOC_Os11g07230 的特青等位基因和 LOC_Os11g07240 的野生稻等位基因编码预测的功能蛋白。基于杂种弱势的遗传继承，LOC_Os11g07240 被暗示为 Hwi1 的候选基因。对 Hwi1 的功能分析将扩展我们对水稻杂种弱势调控的认识。
