大豆矮秆基因Gmdw1的图位克隆与遗传基础研究

Soybean plant height is an important factor which influencing plant type, lodging and yield by controlling the planting density. Therefore, discovery genes involved in regulating plant height is very important not only for basic research of plant architecture morphogenesis, but also for applied research of high-yield breeding program in soybean. Previous research has focused on genetic analysis of three F2 segregation populations which derived from a dwarf mutant and three high stalk soybean varieties. The results of genetic analysis showed that the dwarf trait controlled by a nuclear gene Gmdw1, and located in a 1.8 Mb region. The aim of this project was fine-mapping of the Gmdw1 gene using the densification of linkage markers in parental and secondary mapping population. After sequence and expression analysis of candidate genes located in the fine mapping region, the Gmdw1 gene will be cloned and the functional of Gmdw1 will also be identified by transformation, expression analysis, and other methods. The results of these studies will play a basis for molecular mechanisms of plant height morphogenesis in soybean. Meanwhile, different alleles of Gmdw1 will also be identified in soybean germplasm and the applied value of Gmdw1 will be evaluated by molecular marker development and selection efficiency identification. This research will provide guidance for soybean plant type selection and high-yield breeding by molecular marker assistant selection.

株高是构成大豆株型的重要农艺性状，与植株抗倒伏能力紧密关联；可调控群体种植密度进而影响产量。因此，发掘大豆株高相关基因并解析其功能对推动大豆植株形态建成的基础研究和高产新品种培育的应用研究均具有重要意义。本课题前期研究利用EMS诱变的矮秆突变体与高秆品种杂交构建3个分离群体进行遗传分析，明确矮秆受一对核基因控制，并将该基因定位在物理距离为1.8Mb的区间内。本项目拟利用扩大的F2群体，通过标记加密完成精细定位；结合候选基因的表达分析与序列差异分析图位克隆大豆矮秆基因Gmdw1并研究其功能；为解析大豆株高形成的遗传机制提供理论基础；同时，在种质资源中发掘Gmdw1的等位基因，开发功能标记并明确标记的鉴定效率，进而对Gmdw1基因进行育种价值评估，为大豆分子标记辅助的株型选择和高产育种提供参考。

株高是构成大豆株型的重要农艺性状，与植株抗倒伏能力紧密关联，可调控群体种植密度进而影响产量。本项目以从中品661大豆种子诱变筛选获得的一矮化突变体dw为研究对象，外源赤霉素处理及内源激素含量测定结果表明，dw突变体是一类内源赤霉素合成途径缺陷突变体。遗传分析表明，突变体的矮秆表型受一对核隐性单基因控制。利用dw突变体衍生的F2分离群体，结合BSA-Seq重测序分析和连锁遗传分析，将目的基因精细定位在标记SNP08-1～SSR-08-0716之间，该区间物理距离长度为460 kb，共存在36个开放阅读(ORF)。其中，基因Glyma.08G163900.1编码一种内根-贝壳杉烯合成酶（KS），是赤霉素（GAs）合成途径中一种关键酶。序列分析显示，突变体中Glyma.08G163900.1基因组序列第1224位（位于3rd exon）非同义碱基突变（T→A）引起编码氨基酸序列改变，且该位点突变与突变体的矮秆表型遗传相关。基于该位点开发的分子标记可用于对株高表型的辅助选择。进一步等位变异检测结果分析表明，可能存在有Glyma.08G163900.1的其它位点或其它基因变异可以引起株高表型改变。同时，qPCR分析结果发现，与野生型相比，包括候选基因Glyma.08G163900.1在内的GAs合成及响应相关基因在突变体中的表达水平均较野生型显著降低。