甘蓝型油菜特大籽粒性状主效QTL位点qSWA9-1精细定位

Thousand seeds weight (TSW) as one of the important factors of rapeseed yield had been the focus of genetic improvement in rapeseed breeding. In our previous study supported by National Natural Science Foudation, the major QTL of TSW, qSWA9-1, had been identified by linkage analysis using the extra larger seed germplasm and small seed germplasm as parent materials of F1DH lines. The values of genetic contribution and additive effect of were far larger than that of TSW QTL of previous reports. We further sequenced the whole cDNA sequence of BnARF18 gene which was the first validated gene affecting the seed size in Brassica napus in 2015, in the extra larger seed germplasm and small seed germplasm. The comparative analysis of sequence showed the BnARF18 was not the target gene controlling the trait of extra-large seed. In this study, 300 elite materails were selected as association-mapping population. Combining the data of TSW collected from Wuhan and Kunming in 2 years and the SNPs and InDel markers identified by high-throughput sequencing, region association mapping for TSW trait will be conducted to narrow the interval of the qSWA9-1. The result of this study will facilitate molecular mark assisted larger seed breeding with the extra larger seed germplasm in Brassica napus.

千粒重是油菜遗传改良的重点。项目组在前一个国家基金资助下，利用油菜大、小籽粒种质构建F1DH 群体，连锁作图分析在A9连锁群检测到的主效千粒重QTL位点qSWA9-1，其贡献率及加性效应远超近期同类研究结果。序列分析发现，大、小粒亲本间的BnARF18(首个油菜粒重基因，2015)序列没有差异，表明qSWA9-1为新的千粒重基因位点。本项研究拟以国内外收集的300份遗传代表性材料作为关联分析群体，利用RAD-seq技术，获取SNPs与InDel差别位点；综合武汉、昆明2年2点的田间千粒重考种数据，对qSWA9-1区间进行千粒重性状区域关联分析，获得与千粒重性状极显著关联的峰值SNP/InDel标记；结合F1DH亲本重测序数据，再度循环进行千粒重关联分析，实现qSWA9-1精细定位。研究结果将为克隆新的与千粒重相关基因提供研究基础，为利用特大籽粒种质开展高千粒重育种提供实用分子标记。

千粒重是油菜遗传改良的重点。本研究利用基因组重测序技术结合302份自然株系群体4个生长环境下千粒重拷种数据开展千粒重性状全基因组关联分析，在A09染色体末端检测到一个多环境下稳定存在且高贡献率的千粒重QTL位点-qSWA9-1。以最新的ZS11测序数据为参考基因组结合QTL区间内群体SNP与InDel信息将qSWA9-1位点锁定在A09染色体57.17M-57.25M约80K的区间内。该区间包含10基因，通过序列比较分析与基因功能预测，推测BnaA09T0557500ZS，BnaA09T0557600ZS，BnaA09T0557700ZS与BnaA09T0557900ZS为千粒重qSWA9-1位点潜在的候选基因。项目执行过程中开发了5个可电泳检测的实用InDel标记，并应用于特高千粒重恢复系分子标记辅助转育工作，获得了1份千粒重超过6.0g的特大恢复系-338C。该恢复系组配选育的大籽粒杂交种云油杂37（千粒重5.14±0.23g）已进入田间多点试验。该研究结果为后续克隆新的控制千粒重性状的基因，开展基因功能验证奠定了良好的数据基础，并为利用特大籽粒种质材料开展高千粒重分子标记辅助育种提供了实用分子标记。