小麦面粉白度新主效位点候选基因的发掘和利用

The whiteness and color of wheat flour and its products is an important sensory and market indicators, but at present the average of flour whiteness of wheat main cultivars is lower in our country (74.8), and there is a lack of the cultivars with high flour whiteness and strong gluten. Meanwhile the fierce competition in international market and the serious situation of the food safety in China also urgently need to breed new varieties with natural high flour whiteness and strong gluten. In our previous research, a new major QTL Qfw1D1-1 for flour whiteness was found with accounting for the average of 37.73% of the phenotypic variation in three environments. It was only 0.8 cM from the cfd183 marker. At the same time, conditional QTL analysis showed that the locus was almost not affected by protein content. Therefore in this study, the aims are (1) to fine mapping of this locus by secondary group, (2) to predict the region of candidate genes and identify the candidate gene by combining the BSR-Seq analysis, (3) to develop the functional markers according to the sequence of candidate gene and selecting the Gaocheng8901 with high flour whiteness from backcross population, (4) and to breed the elite lines with both high flour whiteness and strong gluten by pyramiding the genes controlling the flour whiteness and strong gluten using MAS, so that the molecular polymerization will be achieved for genes coding high whiteness, high protein content and strong gluten. These results can help solve the practical problems in the production of high protein content with low whiteness, and it is very important for enhancing the international competitiveness of Chinese wheat with high quality.

小麦面粉及其制品的白度和色泽是一项重要的感官和市场指标，但目前我国主栽小麦品种面粉平均白度仅为74.8，尤其是高蛋白面粉白度低，缺乏高白度强筋小麦品种；同时国际市场的激烈竞争也迫切需要尽快培育出高白度强筋小麦新品种。前期鉴定到一个新的面粉白度主效QTL Qfw1D1-1位点，三个环境下平均解释37.73%的表型变异，离Xcfd183标记只有0.8 cM；基于条件QTL分析，发现该位点不受蛋白质含量的影响。基于此，拟利用以藁城8901为背景的次级群体对该位点进行精细定位，结合BSR-Seq预测鉴定分离其候选基因，进行基因功能和表达模式分析，开发功能标记，实施分子标记辅助选择（MAS）利用，筛选高白度藁城8901和培育高白度强筋小麦新品种（系），实现高白度、高蛋白和强筋基因的分子聚合。该研究结果可帮助解决生产上面粉蛋白质含量高而白度低的生产实际问题，对增强我国优质小麦国际竞争力有很重要的意义。

我国主栽小麦中缺乏高白度强筋小麦新品种，而要培育这类小麦品种，就需要从分子水平上进行改良，挖掘控制面粉白度及其相关性状的重要基因位点。因此，本项目以亲本、RIL群体、回交群体等为材料并结合关联分析，融合基因组学、转录组学、生物信息学等方法，重点开展了高密度遗传图谱构建、面粉白度相关性状的基因位点鉴定及精细定位、候选基因预测、标记开发及高白度新材料的创制等主要研究内容。结果表明：构建了包含8095个标记的高密度遗传图谱，除了鉴定出与面粉白度性状相关的6个新主效位点外，缩小了QFw-1D1-1位点的区间，预测到了23个候选基因；进一步通过BSA重测序，在1D染色体上挖掘到21个候选位点，包含19个候选基因，同时在5A和5D染色体上分别鉴定到18个和8个新的候选区域，分别有13个和10个重要候选基因；BSR-Seq分析鉴定到两个不同发育时期共有基因40个，在15天和25天特异表达的基因数分别为38和51个；同时在5D染色体上鉴定到稳定关联的SNP位点BS00000020_51，候选基因TraesCS5D01G004300和Gsp-1D 基因与籽粒硬度有关，该基因在BSA重测序中也鉴定到。联合分析，鉴定出面粉白度Qfw-1D1-1位点的候选基因TraesCS1D02G338100、TraesCS1D02G338200、TraesCS1D02G438600、TraesCS1D02G438700、TraesCS1D02G048200.1等6个，其中，候选基因TraesCS1D02G338100和TraesCS1D02G338200主要编码乙酰5-羟色胺O-甲基转移酶，该酶与褪黑素的合成有关，其他候选基因主要与酶和蛋白质的合成有关；而5A染色体上鉴定出的候选基因主要是通过影响硫氧还蛋白、谷胱甘肽、类黄酮、黄素等相关酶的合成影响面粉白度；5D染色体上的候选基因通过类胡萝卜素、脂氧合酶、籽粒硬度等相关酶的合成影响面粉白度。1D染色体上开发了10个CAPS标记和6个SNP位点的KASP标记，5A染色体上开发了15个CAPS标记和9个KASP标记；创制高白度小麦新材料14份，其中高白度优质品系3份。发表相关学术论文9篇，其中SCI收录5篇，申请和授权专利各1项，专著2部，齐鲁农业科技奖二等奖1项，培养研究生10名。研究结果对加快我国高白度优质小麦新品种的培育及改良具有重要的意义。