我国特有普通小麦亚种单片段导入系的创制与产量和抗白粉病相关QTL/基因的定位

Yunnan wheat, Xinjiang wheat and Tibetan semi-wild wheat are Chinese endemic wheat sub-species, which were not utilized in wheat breeding in the past. In our previous works, we developed and characterized 991 chromosome segment introgression lines using Yunnan wheat (YN3), Xinjiang wheat (XJ5), Tibetan semi-wild wheat (XZ-ZM19450) and a artificial snythetic wheat (HC-XM1620) as donor parents. Using those introgression lines, we found 39 QTLs for the yield-related trait such as plant height, spike length and grain number per spike. Furthermore, twenty-four elite introgression lines were also be obtained because of their significantly improved agronomic traits compared to receptor parent Shi 4185. In addition, from XJ5, a novel dominant resistant gene PmXJ5 for powdery mildew was found and preliminarily mapped on chromosome 5BS. Based on the previous studies, further programs will be carried out in three aspects. Firstly, the genomic single segment introgression lines will be developed using the 24 elite introgression lines through further-backcrossing with receptor parent Shi 4185 and combining measurements of target traits and molecular marker screen, by which, the genetic effects and applied potential of those elite lines in wheat breeding will be estimated and elucidated. Secondly, the fine-mapping of PmXJ5 gene will be performed by establishing more number of genetic segregation populations. Finally, the yield-related QTLs and PmXJ5 will be transferred into leading wheat cultivars by crossing and backcrossing in order to obtain a serial of elite lines with outstanding target traits (especially for grain number per spike, spike length and powdery mildew-resistance) and better comprehensive traits, which will made them could be directly used as parents for wheat breeding. Our goal are producing a batch of potential lines with extraordinary yield-related traits and disease-resistance and providing valuable clues for systematic estimation of utilizing potential of the Chinese endemic sub-species wheat germplams in China.

云南小麦、新疆小麦和西藏半野生小麦是我国特有的普通小麦亚种，尚未用于小麦育种。前期工作中，我们构建了上述三个小麦亚种和一个人工合成小麦的991个导入系，鉴定出39个与产量性状相关的QTL，筛选到24个综合性状优于受体石4185的导入系，发现一个源于新疆小麦的新抗白粉病基因PmXJ5。本项目将开展3方面研究：（1）进一步与石4185回交，结合目标性状考察和分子标记鉴定，将24个优良导入系构建成单片段导入系，阐明产量性状相关QTL的遗传效应和育种价值；（2）构建更大的作图群体，对PmXJ5进行精细定位；（3）通过转育，将产量性状相关的优异QTL和PmXJ5转移到主栽品种中，培育一批综合性状优良，目标性状（穗粒数、穗长和抗白粉病）突出的育种材料，使之达到直接用作育种亲本的水平。研究目的是为小麦分子育种提供一批产量、抗病性状优异的育种材料，为系统评价我国特有小麦亚种资源的育种潜力提供有价值的参考。

新疆小麦、西藏半野生小麦和云南小麦是我国特有的普通小麦亚种资源，它们主要生长于我国新疆、西藏和云南范围内的贫瘠土地，未经人工选择。我们之前的研究结果显示，它们与我国主栽小麦品种的基因组差异在50%左右，是改良我国小麦重要的遗传资源。本项目共创制1071份导入系，其中以新疆5号为供体的导入系总共493份，以西藏半野生小麦（ZM19450）为供体的导入系总共357份，以云南小麦（YN3）为供体的导入系总共221份。结合农艺性状考察数据，我们对其中150份材料进行简化基因组测序（RRGS）。总共获得24份小麦产量相关性状明显改良的基因组单片段导入系，其中13个导入系的穗粒数性状比石4185显著增加，有19个系的株高比石4185的显著降低。另外，我们采用GWAS的方法发现了一系列的与产量性状相关的基因组片段。发现4B和5A上存在与小麦株高性状显著相关的SNP，其中位于5A上的位点为一个新的控制株高的位点。在1A、1B、3A、4D染色体上发现与株穗数相关的SNP，在5D染色体上发现了与穗长相关的SNP，在1B、3B、5B染色体上发现与小穗数相关的SNP，在3B和4D染色体上发现了与穗粒数相关的SNP。发现了位于4A染色体上有与小麦穗型相关的基因组片段。最后，我们利用优异亚种导入系对小麦品种石4185、矮抗58、济麦22的进行了改良。总共获得28个综合农艺性状优于相应亲本的株系，其中石4185的后代19个株系、矮抗58的后代8个株系、济麦22的后代1个株系株。本项目不仅为研究我国特有普通小麦亚种的基因资源奠定了研究基础，而且提供了利用我国特有普通小麦亚种对我国主栽小麦进行改良的可行性，为进一步利用亚种资源具有一定的提示意义。