Analysis of genetic control and QTL mapping of essential wheat grain quality traits in a recombinant inbred population

Wheat cultivars are genetically crossed to improve end-use quality for traits as per demands of baking industry and broad consumer preferences. The processing and baking qualities of bread wheat are influenced by a variety of genetic make-ups, environmental factors and their interactions. Two wheat cultivars, WL711 and C306, derived recombinant inbred lines (RILs) with a population of 206, were used for phenotyping of quality-related traits. The genetic analysis of quality traits showed considerable variation for measurable quality traits, with normal distribution and transgressive segregation across the years. From the 206 RILs, few RILs were found to be superior to those of the parental cultivars for key quality traits, indicating their potential use for the improvement of end-use quality and suggesting the probability of finding new alleles and allelic combinations from the RIL population. Mapping analysis identified 38 putative QTLs for 13 quality-related traits, with QTLs explaining 7.9–16.8% phenotypic variation spanning over 14 chromosomes, i.e., 1A, 1B, 1D, 2A, 2D, 3B, 3D, 4A, 4B, 4D, 5D, 6A, 7A and 7B. In-silico analysis based on homology to the annotated wheat genes present in database, identified six putative candidate genes within QTL for total grain protein content, qGPC.1B.1 region. Major QTL regions for other quality traits such as TKW have been identified on 1B, 2A, and 7A chromosomes in the studied RIL population. This study revealed the importance of the combination of stable QTLs with region-specific QTLs for better phenotyping, and the QTLs presented in our study will be useful for the improvement of wheat grain and bread-making quality.为匹配烘焙工业需求与大众消费偏好，科研人员通过遗传杂交培育小麦品种，以改良其终端加工品质相关性状。面包小麦的加工与烘焙品质受多种遗传背景、环境因素及其互作效应的共同影响。本研究以两个小麦品种WL711与C306为亲本杂交构建的206份重组自交系（recombinant inbred lines, RILs）群体为材料，开展品质相关性状的表型鉴定。品质性状的遗传分析结果表明，可量化的品质性状存在显著遗传变异，且多年试验中的表型数据均呈现正态分布与超亲分离现象。在206份重组自交系中，有部分株系在关键品质性状上表现优于双亲，表明该群体可用于小麦终端加工品质的遗传改良，同时也预示着可从该RIL群体中挖掘新的等位基因及等位基因组合。连锁定位分析共鉴定出13个品质相关性状的38个潜在数量性状位点（quantitative trait locus, QTL），这些QTL可解释7.9%~16.8%的表型变异，分布于14条染色体上，即1A、1B、1D、2A、2D、3B、3D、4A、4B、4D、5D、6A、7A与7B。基于数据库中已注释小麦基因的同源性开展的虚拟分析（in silico analysis），在总籽粒蛋白质含量QTL qGPC.1B.1的候选区域内鉴定出6个潜在候选基因。在本研究的RIL群体中，还在1B、2A与7A染色体上鉴定到千粒重（thousand kernel weight, TKW）等其他品质性状的主效QTL区域。本研究揭示了稳定QTL与区域特异性QTL结合用于精准表型鉴定的重要性，本研究鉴定到的QTL可用于小麦籽粒品质与面包加工品质的遗传改良。