National Key Laboratory of Crop Genetic Improvement and National Centre of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan 430070, China.
Proc Natl Acad Sci U S A. 2012 Sep 25;109(39):15847-52. doi: 10.1073/pnas.1214141109. Epub 2012 Sep 10.
Heterosis refers to the superior performance of hybrids relative to the parents. Utilization of heterosis has contributed tremendously to the increased productivity in many crops for decades. Although there have been a range of studies on various aspects of heterosis, the key to understanding the biological mechanisms of heterotic performance in crop hybrids is the genetic basis, much of which is still uncharacterized. In this study, we dissected the genetic composition of yield and yield component traits using data of replicated field trials of an "immortalized F(2)" population derived from an elite rice hybrid. On the basis of an ultrahigh-density SNP bin map constructed with population sequencing, we calculated single-locus and epistatic genetic effects in the whole genome and identified components pertaining to heterosis of the hybrid. The results showed that the relative contributions of the genetic components varied with traits. Overdominance/pseudo-overdominance is the most important contributor to heterosis of yield, number of grains per panicle, and grain weight. Dominance × dominance interaction is important for heterosis of tillers per plant and grain weight and has roles in yield and grain number. Single-locus dominance has relatively small contributions in all of the traits. The results suggest that cumulative effects of these components may adequately explain the genetic basis of heterosis in the hybrid.
杂种优势是指杂种相对于亲本的表现优势。几十年来，杂种优势的利用极大地提高了许多作物的生产力。尽管已经有许多关于杂种优势各个方面的研究，但理解作物杂种优势表现的生物学机制的关键是遗传基础，其中很大一部分仍未被描述。在这项研究中，我们利用从一个优秀的水稻杂种衍生的“不朽 F2”群体的重复田间试验数据，剖析了产量和产量构成性状的遗传组成。基于群体测序构建的超高密度 SNP -bin 图谱，我们计算了整个基因组中单基因和上位性遗传效应，并鉴定了与杂种优势相关的成分。结果表明，遗传成分的相对贡献随性状而变化。超显性/拟超显性是产量、每穗粒数和粒重杂种优势的最重要贡献者。显性×显性互作对每株分蘖数和粒重的杂种优势很重要，并在产量和粒数中起作用。单基因显性在所有性状中贡献相对较小。结果表明，这些成分的累积效应可能足以解释杂种优势的遗传基础。
