大麦新矮源华矮11的矮秆形成机理及矮秆基因的克隆研究

The Huaai 11 was a new dwarf germplasm, our research group found it at Daofu County in Sichuan Province, and identified a stable dwarf germplasm and designated it as Huaai 11. Huaai 11 is only about 40 cm in height and has the characteristic of early maturity, high yield, and higher general combining ability. The dwarf trait of Huaai 11 is controlled by a single recessive gene btwd1. Previously, we have mapped the dwarf gene btwd1 to the long arm of barley chromosome 7H. The purpose of this study will clear physiological and biochemical reactions characteristic of plant height of Huaai 11 by analyzing physiological and biochemical indicators such as GA, IAA, BR, ABA and various enzymes using a DH population of Huaai 11 × Huadamai 6. Since the inheritance of btwd1 gene follows the Mendelian inheritance, a F2 population from Huadamai 6 and Huaai 11 have been constructed for this study. Methods that will be used for this study include constructing a large DNA library, building a high density genetic linkage map. according to the principles of the map-based cloning method, two tightly linked molecular markers will be identify in the both sides of dwarfing gene btwd1 and use it as a probe. A genetic fragment containing the target gene btwd1 will be isolated and cloned by chromosome walking gradually approaching the target gene or chromosome landing, jumping and connection methods. This study will clear dwarfing effect and dwarfing mechanism of the new dwarf germplasm Huaai11 and overcome the problem of single dwarf germplasm and dwarfing gene in barley breeding in China, and the results achieved with independent intellectual property rights.

"华矮11"是本课题组在四川省道孚县发现并经多年选育而成的一份株高约40厘米的特矮秆新种质，其同时具备早熟、丰产和一般配合力高等优良特性，它的矮秆性受隐性单基因btwd1控制，已定位于大麦染色体7H长臂上。通过对高、矮秆亲本及DH群体的生理生化指标如GA、IAA、BR、ABA和各种酶类等进行分析，明确其矮秆的生理生化反应特征。根据图位克隆法的原理，利用已构建的 F2代定位群体，构建含有目的基因的大片段DNA基因组文库和高密度的分子标记遗传图谱，对目的基因btwd1进行精细定位，同时，在矮秆基因btwd1两侧确定一对紧密连锁的分子标记，并以此为探针，通过染色体步移逐步逼近目的基因或利用染色体登陆、跳步和连接等方法将含目的基因btwd1的基因组片段分离克隆出来。本研究将明确新矮源华矮11的矮化效应和矮化机理，克服我国大麦育种上矮源和矮秆基因单一化的问题，所得成果具有自主知识产权。

项目“大麦新矮源华矮11的矮杆形成机理及矮杆基因的克隆研究”目前已取得了较大的进展，构建了包括1962个分子标记覆盖1375.8cM的高密度遗传连锁图谱，平均图距0.7cM。对目的基因btwd1进行了精细定位，在矮秆基因btwd1两侧确定了一对紧密连锁的分子标记7HL-6335336和7-249275418，这一对标记分别与目的矮杆基因btwd1的距离为0.9cM和0.7cM，通过染色体步移逐步逼近的方法正在定位更紧密连锁的分子标记来分离克隆该基因。同时，收集了多年多点的成熟期农艺性状、生理性状、株高相关性状、叶部性状以及苗期水培性状等数据，利用已构建的高密度遗传连锁图谱对这些性状进行了QTL定位。其中7个株高相关性状共探测到20个主效QTL，解释了27.19-59.73%的表型变异；7个生理性状和3和形态性状共探测到38个主效QTL，解释了6.53-31.29%的表型变异；10个成熟期农艺性状共探测到111个主效QTL，解释了16.06-44.40%的表型变异；21个苗期性状共探测到70个主效QTL，解释了5.01-77.78%的表型变异；8个叶部性状共探测到57个主效QTL，解释了5.17-37.11%的表型变异；且大多数QTL表现了与环境互作的现象。另外，对两亲本华矮11和华大麦6号在不同时期的代谢产物和生理生化指标进行了检测分析，筛选出135种差异代谢产物正在群体中进行遗传分析。通过该项目的研究，发表了SCI论文6篇，培养了研究生6人，为我国大麦的基础研究和分子辅助选择育种奠定了坚实的基础。