Yu S B, Li J X, Xu C G, Tan Y F, Gao Y J, Li X H, Zhang Q, Saghai Maroof M A
National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China.
Proc Natl Acad Sci U S A. 1997 Aug 19;94(17):9226-31. doi: 10.1073/pnas.94.17.9226.
The genetic basis of heterosis was investigated in an elite rice hybrid by using a molecular linkage map with 150 segregating loci covering the entire rice genome. Data for yield and three traits that were components of yield were collected over 2 years from replicated field trials of 250 F(2:3) families. Genotypic variations explained from about 50% to more than 80% of the total variation. Interactions between genotypes and years were small compared with the main effects. A total of 32 quantitative trait loci (QTLs) were detected for the four traits; 12 were observed in both years and the remaining 20 were detected in only one year. Overdominance was observed for most of the QTLs for yield and also for a few QTLs for the component traits. Correlations between marker heterozygosity and trait expression were low, indicating that the overall heterozygosity made little contribution to heterosis. Digenic interactions, including additive by additive, additive by dominance, and dominance by dominance, were frequent and widespread in this population. The interactions involved large numbers of marker loci, most of which individually were not detectable on single-locus basis; many interactions among loci were detected in both years. The results provide strong evidence that epistasis plays a major role as the genetic basis of heterosis.
通过使用覆盖水稻全基因组的包含150个分离位点的分子连锁图谱，对一个优良水稻杂交种的杂种优势遗传基础进行了研究。在2年时间里，从250个F(2:3)家系的重复田间试验中收集了产量及产量构成的三个性状的数据。基因型变异解释了总变异的约50%至80%以上。与主效应相比，基因型与年份之间的互作较小。四个性状共检测到32个数量性状基因座（QTL）；其中12个在两年中均被观测到，其余20个仅在一年中被检测到。大多数产量相关QTL以及一些产量构成性状相关QTL表现出超显性。标记杂合性与性状表达之间的相关性较低，表明总体杂合性对杂种优势的贡献较小。双基因互作，包括加性×加性、加性×显性和显性×显性，在该群体中频繁且广泛存在。这些互作涉及大量标记位点，其中大多数在单基因座水平上无法单独检测到；两年中均检测到许多位点间的互作。结果提供了强有力的证据，表明上位性作为杂种优势的遗传基础起着主要作用。
