基于全基因组重测序技术的橡胶草高密度遗传图谱构建及含胶量QTL定位

Taraxacum kok-saghyz Rodin (TKS)，as important rubber producing crops emerging in recent years, with the advantages of the ability of adaptable, short period of growth, suitable for mechanized planting and harvesting, resilience, biocompatibility, strong anti-allergic properties, was given widely attention. However, shortage of TKS germplasm resources available in China, especially high rubber content gemplasm, hinders the breeding and industrialization development of TKS, which make the improvement of rubber content main breeding direction in TKS. The out-crossing nature of reproduction and genome complexity of TKS make conventional breeding such direct single plant selection difficult and inefficient. As molecular marker assisted selection can enhance the speed and effectiveness of plant breeding, this research focuses on the construction of high-density genetic map and location of the rubber content related loci in TKS. F1 population will be constructed using two TKS lines with great difference among their rubber content, and 150 F1 individuals will be selected randomly as mapping population to construct high-density genetic map based on two way pseudo-testcross strategy using whole-genome resequencing. Combining the rubber content of the mapping population which will be measured using near infrared spectroscopy, and the SNP data of high-density genetic map, the rubber content-associated loci will be mapped finally. The results will improve the breeding efficiency of TKS with high rubber content, and provied theoretical and practical base for gene mapping and marker-assisted breeding in the further.

橡胶草又称俄罗斯蒲公英，因其根部橡胶含量高，品质优良，适应性强等诸多优点，成为近年来备受关注的重要产胶作物之一。目前，我国橡胶草种质资源少且含胶量普遍偏低，还不能满足产业化发展的需求，因此，高含胶量种质的选育是橡胶草主要育种方向之一，但橡胶草的异交特性和遗传复杂性使传统的单株选择育种效率低下。鉴于分子标记辅助育种具有相对高效性，本项目拟构建橡胶草高密度SNP遗传图谱，筛选和定位含胶量QTL。本项目以两个含胶量差异大的橡胶草株系杂交构建F1代，并从中随机选择150个F1单株与2个亲本构成作图群体；基于“双假测交”策略采用全基因组重测序技术开发SNP标记，构建橡胶草高密度遗传图谱；结合F1代作图群体利用红外光谱法测定的含胶量数据，利用复合区间作图法定位含胶量相关QTL。本研究将极大提高高含胶量橡胶草育种效率，为今后橡胶草图位克隆及分子标记辅助育种等许多应用研究提供理论依据和技术支持。

橡胶草又称俄罗斯蒲公英，因其根部橡胶含量高，品质优良，适应性强等诸多优点，成为近年来备受关注的重要产胶作物之一。目前，我国橡胶草种质资源少且含胶量普遍偏低，还不能满足产业化发展的需求，因此，高含胶量种质的选育是橡胶草主要育种方向之一。鉴于分子标记辅助育种具有相对高效性，本项目以两个含胶量差异大的橡胶草株系（高含胶量X51×低含胶量166）杂交构建F1代，并利用其127个F1单株与2个亲本构成作图群体，基于“双假测交”策略采用全基因组重测序技术开发SNP标记，成功构建橡胶草高密度SNP遗传图谱。遗传图谱包含16个连锁群，由3886个SNP组成，中性图总图距为2,141.44cM。结合F1代作图群体的含胶量数据，利用复合区间作图法共检测到3个含胶量相关QTL，分别位于第3连锁群和第14连锁群上。3个含胶量QTL位点共包含14个SNP和14个候选基因，7个SNP设计引物成功，其中，2个标记M2315938和M1478150通过鉴定可提高高含胶量橡胶草的筛选效率。另一方面，为阐明橡胶草的天然橡胶（NR）合成在转录水平上的调控机制，利用ONT技术获得了高含胶量和低含胶量株系橡胶草的高质量全长根转录组数据，并对高/低含胶量橡胶草株系之间进行比较转录组分析。结果显示，NR合成相关基因的表达水平与NR产量成正比；在使用共同底物（IPP或乙酰辅酶A）时，NR与某些代谢产物合成之间存在竞争。本研究将极大提高高含胶量橡胶草育种效率，为今后橡胶草图位克隆及分子标记辅助育种等许多应用研究提供理论依据和技术支持。在项目资助下，发表SCI论文1篇，申请国家专利1项，参加国内学术会议交流1人次，培养科研辅助人员1名。