小麦品系北农6号新矮秆主效QTL QPh-2A.2精细遗传解析

Plant height, an important agronomic trait, has great impact on wheat plant architecture and grain production．Reduction of plant height and improvement of plant lodging resistance are the important objectives in wheat breeding, genetic dissection of wheat plant height will have great impact on breeding for dwarf, high yield cultivars. In previous research, preliminary QTL analysis on plant height in recombinant inbred lines (RILs) derived from the cross 'Yanda1817/Beinong6' was performed using constructed high-density genetic linkage map via wheat Infinium 9K iSelect SNP screening. Based on these research basis, fine genetic dissection of the newly discovered dwarf major QTL QPh-2A.2 derived from 'Beinong6' will be conducted by SSR, EST analysis and comparative genomic analysis. Dwarf major QTL's markers will be employed in marker assistant selection (MAS) to construct dwarf major QTL QPh-2A.2 's near-isogenic lines (NILs) via backcrossing strategy, and a fine mapping population for major QTL will be created. Comparative genomic analysis on dwarf major QTL QPh-2A.2 will be also conducted to develop more closely linked markers by comparing with the orthologous genomic sequences of rice, brachypodium, barley, and the scaffold sequences of wheat A genome, a fine genetic linkage map of QPh-2A.2 could be constructed. These results can lay foundations for the positional cloning of the dwarf major QTL in the further research projects.

株高是影响小麦株型和产量的一个重要农艺性状。降低株高和提高抗倒伏性是小麦育种的重要目标，株高的遗传解析对小麦矮秆高产品种的培育具有重要指导意义。前期研究已利用小麦Infinium iSelect 9k SNP芯片技术构建了骨干亲本燕大1817与超高产品系北农6号重组自交系群体的高密度遗传连锁图谱，并对株高性状进行了QTL初定位。在此基础上，本研究拟利用SSR、EST标记和比较基因组学分析对新发现的来自北农6号的矮秆主效QTL位点QPh-2A.2进行精细遗传解析。通过回交转育和利用与QPh-2A.2连锁的分子标记进行分子标记辅助选择，创制QPh-2A.2位点近等基因系，构建其精细定位的次级作图群体。结合利用水稻、短柄草、大麦和小麦A基因组的scaffold序列进行比较基因组学分析，开发与QPh-2A.2连锁更紧密的新标记，对QPh-2A.2进行精细遗传定位，为该主效QTL的图位克隆奠定基础。

株高是影响小麦株型和产量的一个重要农艺性状。降低株高和提高抗倒伏性是小麦育种的重要目标，株高的遗传解析对小麦矮秆高产品种的培育具有重要意义。本研究在利用小麦Infinium iSelect 9k SNP芯片技术构建了骨干亲本燕大1817与超高产小麦品系北农6号重组自交系的高密度遗传连锁图谱基础上，对该重组自交系群体进行了6年3点共10个环境型的田间试验，并对株高性状进行了QTL定位。结果表明：来自于北农6号的矮秆主效QTL QPh-2A.2位点能同时在10个环境型中检测到，表型贡献率为7.29%-14.61%。在此染色体区间并未见小麦株高性状QTL或矮秆基因的报道，因此，推测QPh-2A.2是一个新的控制株高性状的稳定主效QTL位点。在此基础上，利用二穗短柄草、水稻和中国春参考基因组序列进行比较基因组学分析，结合采用BSR_Seq转录组测序技术，开发了45个与主效QTL QPh-2A.2位点紧密连锁的分子标记。此外，通过回交转育和利用与QTL位点QPh-2A.2连锁的分子标记进行分子标记辅助选择，创制了QPh-2A.2位点BC3F1近等基因系，并构建了包含6014个单株的BC3F2次级作图群体，从中筛选出了235个重组交换单株。利用上述开发的与目标QTL紧密连锁的分子标记构建了QPh-2A.2位点高密度饱和遗传连锁图谱，并最终将QPh-2A.2位点定位与2AL染色体上分子标记WGGC6880至WBUA737区间内，染色体覆盖区间为0.38cM。此研究为该主效QTL的图位克隆奠定了坚实的基础。