簇毛麦4VS染色体结构变异系创制及抗小麦黄花叶病基因Wss1的染色体区段定位

The genetic variability within cultivated wheat has been gradually eroded, which has become a major bottleneck for wheat breeding. The wild relatives of cultivated wheat represent a rich pool of genetic variation that has great potential for wheat improvement. These species exhibit huge diversity in phenotype and adaptation to a wide range of environments, desirable traits such as resistance or tolerance to biotic and abiotic stresses. The transfer of useful genes from wild species through wide hybridization and the development of alien chromosome lines will enrich the genetic diversity of crop breeding. The induced series of chromosome structural aberrants will provide useful genetic resources not only for wheat improvement, but also for fine mapping and cloning the interest genes located on alien chromosome as well as comparative genomics research.Wheat yellow mosaic virus(WYMV) disease has become one of the most serious diseases affecting wheat production in China. In our previous research, a WYMV resistance gene, Wss1, has been located on the short arm of 4V chromosome of Haynaldia villosa. In this proposal, using wheat-H.villosa disomic substitution line DS4V(4D) and T4VSo4DL translocation line developed in our lab, chromosome structural aberrants involving different region of chromosome 4VS will be induced through a combination of technique of both homoeologous chromosome pairing system (ph1b gene mutant) and ionizing-irradiation. These lines will be characterized for their chromosome constitution by FISH and marker analysis and evaluated for their resistance to WYMV. Wss1 gene will be further mapped to a smaller fragment regions of chromosome 4VS. The outcomes of this research will lay solid foundation for the utilization of Wss1 gene in breeding program as well as the cloning the target gene.

栽培品种遗传基础日趋狭窄已成为小麦育种取得突破性进展的主要瓶颈。小麦近缘种属蕴藏丰富的基因资源，将其中的优良基因导入普通小麦，是拓宽小麦遗传基础、推进小麦育种取得突破性进展的有效途径。诱导创制外源染色体结构变异，既可促进外源优异基因有效利用，系列结构变异体也是外源基因定位、克隆和比较基因组学研究的重要材料。本项目前期研究中发现携带4VS染色体的小麦-簇毛麦异染色体系高抗小麦黄花叶病，将该基因定名为Wss1。本研究将利用抗病的4V（4D）代换系和T4VSo4DL易位系，综合利用ph1b突变体和电离辐射技术，高效诱致和精确鉴定涉及4VS不同区段和片段大小不同的结构变异体，对结构变异体进行黄花叶病抗性鉴定，更精确地定位Wss1基因。研究成果不仅为Wss1基因的克隆奠定材料基础，也可为小麦抗黄花叶病育种提供新的基因资源。

栽培品种遗传基础日益狭窄已成为小麦育种取得突破性进展的主要瓶颈。小麦近缘种属蕴藏丰富的基因资源，将其中的优良基因导入普通小麦，是拓宽小麦遗传基础，推进小麦育种取得突破性进展的有效途径。本项目前期研究中发现携带4VS染色体的小麦-簇毛麦异染色体系高抗小麦黄花叶病，将该基因定名为Wss1。为了更好的利用此基因，本项目利用比较基因组学的原理，利用设计的小麦第四部分同源群染色体的EST-PCR引物和SSR引物，筛选出能特异追踪簇毛麦4V染色体的特异分子标记58个，其中4VS染色体臂特异分子标记32个，4VL染色体臂特异分子标记26个。在T4DL•4VS/CS ph1b//CS ph1b BC1F2代植株中，共筛选到涉及簇毛麦4VS染色体的小片段顶端易位26个，中间插入易位17个。在DS4V(4D)/CS ph1b//CS ph1b BC1F2代植株中共筛选到大片段易位12个，涉及簇毛麦4VS染色体的小片段顶端易位10个，还筛选到多个涉及簇毛麦4VS和4VL染色体的整臂易位及端体材料。将筛选到的涉及4VS染色体的小片段易位系套袋自交，共选育到纯合顶端易位系31份，纯合中间插入易位系13份。利用60Co-γ射线处理T4DL•4VS纯合易位系的花粉以及成熟雌配子，并与普通小麦品种扬麦158进行杂交。利用基因组原位杂交 (Genomic in situ Hybridization, GISH) 技术对M1植株的根尖体细胞有丝分裂中期染色体进行鉴定，筛选含有簇毛麦4VS染色体结构变异的单株回交或自交。在辐射后代中，利用GISH技术共检测到56个结构变异体，其中包括26个小片段顶端易位、22个中间插入易位、5个缺失和3个其他结构变异类型。对选育到的新的小麦-簇毛麦纯合结构变异体结合黄花叶病抗性鉴定、GISH以及分子标记分析结果，将抗WYMV基因进一步定位于4VS染色体的末端FL值0.78-1.00的染色体区段上。本研究所获得的携有抗WYMV基因的小片段易位系和分子标记为小麦黄花叶病抗病育种以及分离克隆该抗病基因奠定了坚实的基础。