基于QTL定位分析小麦株高的杂种优势

为探讨小麦株高杂种优势的分子遗传基础,以小麦品种花培3号和豫麦57杂交F1经染色体加倍获得的DH群体168个株系为材料,构建了一套含168个杂交组合的"永久F2"群体。利用复合区间作图法,在3个环境中进行了基于QTL定位的株高杂种优势分析,共检测到3个加性效应位点、2个显性效应位点、4对上位效应位点(包括加性×加性、加性×显性、显性×加性和显性×显性)和20个杂种优势位点。位于2D、4D和5B2染色体上的QPh2D、QPh4D和QPh5B2在3个环境中同时被检验到,受环境影响小,表达稳定。在2D染色体上相近的区域定位出多个杂种优势位点,其中QPh2D-2和QPh2D-7可解释杂种优势表型变异的29.77%和55.77%。在7D染色体的Xwmc273.2-Xcfd175之间定位出同一个杂种优势位点Qph7D-2。结果表明,在2D、4D和7D染色体上这些区域存在一些对小麦株高的杂种优势起重要作用的位点。

Analysis of Plant Height Heterosis Based on QTL Mapping in Wheat

Plant height (PH) is an important indicator for plant type, population size, biomass, and resistance to lodging. Besides, it is also associated with grain yield in cereal crops. Thus, it is a constant focus in genetics and heterosis of wheat (Triticum aestivum L.). This study aimed at studying the molecular genetic basis of plant height heterosis in wheat. From a set of doubled haploid (DH) lines derived from Huapei 3 × Yumai 57, an “immortalized F₂” population was constructed with 168 single crosses. The DH lines, IF₂ population, and the parents were evaluated for plant height in three environments, i.e., in Tai’an, Shandong Province, in 2007 and 2008 cropping seasons and in Jiyuan, Henan Province, in 2008 cropping season. Based on the genetic map of quantitative trait locus (QTL) constructed in our previous study, we analyzed the heterosis of PH of wheat using the composite interval mapping method. A total of three additive QTLs, two dominance QTLs, four pairs of epistatic QTLs (including additive × additive, additive × dominance, dominance × additive, dominance × dominance), and 20 heterotic loci were detected for PH in the three environments. Two QTLs, Qph2D and Qph4D, were detected on chromosomes 2D and 4D with minor interaction of additive by environment. In addition, several other heterotic loci for PH were also identified on chromosome 2D at very close regions with similar marker intervals. Of them, QTLs Qph2D-2 and Qph2D-7 explained the variance of PH by 29.77% and 55.77%, respectively. Another QTL associated with PH heterosis, Qph7D-2, was mapped in the marker interval between Xwmc273.2 and Xcfd175 on chromosome 7D in the three environments. The results indicated that a few QTLs on chromosomes 2D, 4D, and 7D play an important role in PH heterosis in wheat. These loci have potential use for the improvement of PH in wheat breeding assisted with molecular markers.