苦荞主要产量相关性状的全基因组关联分析

Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn) is an important medicinal and edible food crop rich in flavonoids, which is a new health food resources in the 21st century. Improving the yield is one of the most important objectives of tartary buckwheat breeding. The yield and yield related traits are complex quantitative trait in buckwheat, the genetic mechanism is complicated and largely unknown at present. Mapping and cloning the gene for yield and yield related traits in tartary buckwheat is crucial for uncovering the genetic mechanism of yield formation, and improving the yield of tartary buckwheat. The flower of tartary buckwheat is vulnerable and it's difficult to obtain hybrid seeds. At present, a new established gene mapping strategy that is called association mapping, which based on natural population and linkage disequilibrium is becoming one of the most powerful genes mapping strategy and which didn't need to construct segregating populations. In this study, we plan to sequencing 200 buckwheat accessions with extensive genetic variation using the tGBS (Tunable Genotyping- By-Sequencing ) sequencing technology, assembled the reference genome of tartary buckwheat and calling the SNP covering the whole genome. The LD decay distance of tartary buckwheat will be evaluated, the population structure and the kinship between the buckwheat accessions will be calculated. The yield and eight yield related traits for each accession will be investigated in three different location across two years, and whole genome association mapping of these traits will be conducted. In this study, several QTL controlling yield and yield related traits will be identified, the genetic basis of yield formation preliminarily uncovered and some elite allele will be identified. The information obtained in this study will greatly accelerate the progress of buckwheat molecular breeding.

苦荞药食同源，富含生物类黄酮，是21世纪新型保健食品资源。提高其籽粒产量是苦荞育种的一个重要目标。苦荞产量和产量相关性状多为数量性状，遗传机理复杂，定位和克隆苦荞产量相关性状基因对于揭示荞麦产量形成的遗传机理、提高荞麦产量具有重要意义。苦荞花器脆弱，难以通过杂交构建分离群体。基于自然群体和连锁不平衡的关联分析方法不需要专门构建分离群体，是作物数量性状基因定位的新方法。本研究中拟利用tGBS (Tunable Genotyping-By-Sequencing) 测序技术对具有广泛遗传变异的200个苦荞品种进行测序，拼接组装苦荞参考基因组，进行全基因组SNP分析；分析苦荞基因组LD衰减水平、群体结构和苦荞品种间的亲缘关系；2年3点考察每个苦荞品种的产量和8个主要产量相关性状，对它们进行全基因组关联分析，定位QTL。系统剖析荞麦产量形成的遗传基础，发掘优良等位基因，为苦荞分子育种奠定基础。

苦荞药食同源，富含生物类黄酮，是21世纪新型保健食品资源。提高其籽粒产量是苦荞育种的一个重要目标。苦荞产量和产量相关性状多为数量性状，遗传机理复杂，定位和克隆苦荞产量相关性状基因对于揭示荞麦产量形成的遗传机理、提高荞麦产量具有重要意义。本研究利用RAD-seq测序技术对具有广泛遗传变异的200个苦荞品种进行简化基因组测序，进行全基因组SNP分析，获得覆盖全基因组的SNP标记273206个，InDel标记66152个，基因组杂合标记的比例为12.44%。利用SNP标记对200份苦荞进行群体结构分析，发现200份苦荞可以分成5个亚群，主成分分析发现头两个主成分能够解释分子标记总变异的63.29%，进化树分析的结果与主成分和群体结构分析结果相对应。分析样本间亲缘关系，发现超过63%的样本之间的亲缘关系接近0，少于5%的样本亲缘关系大于0.5。分析苦荞基因组LD衰减水平，全基因组水平上苦荞LD衰减距离为220kb，不同染色体上LD衰减距离变异范围为110kb-465kb。分化系数和选择压力分析发现，西部、西南和西北地区两两之间的分化系数均大于0.7，并分别检测出西部、西南、西北地区特异的受选择基因个数分别为7,11和50。连续多年在杨凌、榆林和宝鸡种植苦荞自然群体，对株高、茎粗、主茎节数、分枝数、分枝部位、花簇数、千粒重、粒长、粒宽、粒重、开花期、成熟期、蛋白含量、脂肪含量、黄酮含量等性状进行了表型鉴定，发现这些性状在不同环境下均呈现连续的表型变异且环境间差异不同。对这些性状进行全基因组关联分析，每个性状能检测到4-59个与性状显著关联的标记。本项目的研究结果为苦荞分子育种和系统克隆苦荞产量相关性状基因奠定了坚实的基础。