Genetic dissection of an elite rice hybrid revealed that heterozygotes are not always advantageous for performance.
Genetic dissection of an elite rice hybrid revealed that heterozygotes are not always advantageous for performance.
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发表时间：
2002-12
期刊：
影响因子：
3.3
通讯作者：
J. Hua;Yongzhong Xing;Cai-guo Xu;X. L. Sun;Sibin Yu;Qifa Zhang
中科院分区：
文献类型：
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作者：
J. Hua;Yongzhong Xing;Cai-guo Xu;X. L. Sun;Sibin Yu;Qifa Zhang
我们引入了一个实验设计，产生了一个“永生化的F（2）”群体，允许完全解剖数量性状的遗传成分。通过两年多的重复田间试验收集了永生化F（2）的产量和三个组成性状的数据。使用231个标记位点，我们将遗传效应分解为单个组分，并评估了所有基因型在单位点和双位点水平上的相对表现。单位点分析共检测到40个QTL。约一半的QTL的显性效应为负，导致很少的“净”正显性效应。基因型杂合度与性状表现的相关性较低。大量的双基因相互作用，包括AA，AD和DD，检测到的所有性状，与AA作为最普遍的相互作用。互补的两个位点的纯合子往往表现最好的九种基因型的许多两个位点的组合。虽然累积的小优势比两个位点的组合可以部分解释杂种优势的遗传基础，双杂合子经常表现出边际优势，双杂合子从来没有在任何两个位点的组合中的最佳基因型。由此得出结论，杂合子不一定是有利的性状表现，即使在基因型来自这样一个高度杂种优势。
We introduced an experimental design that produced an "immortalized F(2)" population allowing for complete dissection of genetic components underlying quantitative traits. Data for yield and three component traits of the immortalized F(2) were collected from replicated field trials over 2 years. Using 231 marker loci, we resolved the genetic effects into individual components and assessed relative performance of all the genotypes at both single- and two-locus levels. Single-locus analysis detected 40 QTL for the four traits. Dominance effects for about one-half of the QTL were negative, resulting in little "net" positive dominance effect. Correlation between genotype heterozygosity and trait performance was low. Large numbers of digenic interactions, including AA, AD, and DD, were detected for all the traits, with AA as the most prevalent interaction. Complementary two-locus homozygotes frequently performed the best among the nine genotypes of many two-locus combinations. While cumulative small advantages over two-locus combinations may partly explain the genetic basis of heterosis of the hybrid as double heterozygotes frequently demonstrated marginal advantages, double heterozygotes were never the best genotypes in any of the two-locus combinations. It was concluded that heterozygotes were not necessarily advantageous for trait performance even among genotypes derived from such a highly heterotic hybrid.