芥菜型油菜多室基因Bjmc2的精细定位

Fine Mapping of Polycyetic Gene (Bjmc2) in Brassica juncea L.

芥菜型多室油菜的产量比普通两室油菜更高,定位乃至克隆多室基因可为油菜遗传改良及解释多室角果形成机制创造条件。本研究通过验证JD11-2家系衍生群体仅在BjMc2位点上存在差异,可用于BjMc2的定位。采用AFLP结合BSA法分析BC5和BC6群体,筛选到1个与BjMc2连锁的AFLP标记并转化为SCAR标记SC1。基于该AFLP标记序列信息,利用白菜同源序列设计SSR引物和SCAR引物,获得11对SSR标记和1对SCAR标记。通过在芥菜型油菜BAC文库中的挑选,获得2个覆盖目标区域的单克隆,由此开发1个SSR标记。将获得的SCAR和SSR标记扫描BC7群体,构建了两室性状基因BjMc2的遗传连锁图,两侧最近标记ZX17和BACsr96与目标基因之间的遗传距离分别为0.048 cM和0.340 cM,并定位到白菜A7 Scaffold 000019的946~1014 kb之间,约68 kb物理距离。

Multilocular plants have a higher seed yield than bilocular plants in B. juncea, mapping and cloning the multilocular gene（s） might be helpful for rapeseed genetic improvement and explanation of the multilocular trait development mechanism. This study verified backcross populations derived from JD11-2 family different at BjMc2 locus only can be used for BjMc2 mapping. Using AFLP assay and BSA method in BC5 and BC6 generations, one AFLP marker linked to the target gene was obtained and converted to SCAR marker （SC1）. On the basis of homologous sequences of the AFLP maker in B. rapa, 11 SSR markers and one SCAR marker were identified. Through the screening in the ZBjH BAC library of Brassicajuncea, two BACs covered the target area were selected and one SSR marker was developed. All the developed SCAR and SSR markers were then used to detect the BC7 population, and a linkage map for the bilocular gene BjMc2 was built. ZX17 and BACsr96, the closest flanking markers, were mapped at 0.048 cM and 0.340 cM distant from the BjMc2 gene, respectively. Bjmc2 is positioned of 68 kb between 946 kb and 1014 kb in the Scaffold 000019 physical map of A7 in B. rapa. This result would lay a foundation for cloning polycyetic gene Bjmc2 and selecting polycyetic lines by marker-assisted selection.