基于高通量GBS-SNP标记的栽培燕麦六倍体起源研究

栽培六倍体燕麦是世界重要粮食作物,理清其起源对燕麦种质资源的高效利用和保护具有重要意义。本研究利用GBS (genotyping by sequencing)对27份来自中国的大粒裸燕麦材料测序,结合先前发表的包括6个六倍体燕麦种在内的66份燕麦材料的GBS数据进行SNP挖掘。UNEAK管道挖掘共计得到MAF大于0.5, call rate大于0.95的SNP标记8902个。进一步剔除缺失值大于0.15的4个燕麦材料后,对其余89份材料进行PCA分析、STRUCTURE分析以及UPGMA聚类分析。结果表明,在野生种中,除A. sterilis外,大多数来自同一物种的材料聚为一类,不同物种间能够较好地分开,表明这些物种之间存在较强的遗传分化。聚类分析将供试材料分为分别代表野生种和栽培种的2支,表明野生种和栽培种之间存在明显的遗传差异;在栽培种中, A. sativa与A. byzantina具有较高的遗传多样性,分散在不同的类群中,二者未出现明显的遗传分化,具有较高的遗传同质性, A. sativa ssp. nuda与A. sativa亲缘关系较近,但存在一定的遗传分化,因此形成独立的类群。值得注意的是,来自野生种A. sterilis的材料被分在2个类群中,其中来自西南亚地区(伊朗-伊拉克-土耳其地区)的居群与A. sativa和A. byzantina聚在一起,揭示此地区的A. sterilis居群可能是A. sativa和A. byzantina的祖先种。野生种A. hybrida显示出与A. fatua较高的遗传同质性,因此将其作为A. fatua的亚种较为合理。本研究为栽培六倍体燕麦起源提供了理论依据。

Hexaploid ancestor of cultivated hexaploid oats inferred from high throughput GBS-SNP markers

Cultivated hexaploid oat is one of the most important cereal crops in the word, clearing its hexaploid ancestor would substantially improve the utilization efficiency of the genetic resources of oat, and therefore provide theoretical reference for oat germplasm conservation. In this study, 27 naked oats originated from China were sequenced by using GBS (genotyping by sequencing). SNPs were calling by combining the previously published GBS data of another 66 hexaploid oats including six species using UNEAK pipeline. A total of 8902 SNPs with MAF > 0.5, call rate > 0.95 were obtained. Four taxa with missing value greater than 15% were excluded for further analyses. Finally, 89 oat taxa meeting the requirement were used for PCA, STRUCTURE and UPGMA clustering analyses. All three analyses revealed some consistent results as follows: most wild hexaploid oats with the exception of A. sterilis showed strong genetic differentiations among each other, resulting in a grouping by species. Clustering analysis divided all the taxa into two clusters representing wild species and cultivated species, respectively, indicating some significant genetic differences existed between this two types of hexaploids. Within cultivated hexaploid oats, A. byzantina showed a high degree of genetic homogeneity with A. sativa, while naked oats differed from the others and formed an independent subcluster with close relationships with A. sativa. The taxa from the wild hexaploid species A. sterilis were mainly subdivided into two groups. Notably, these accessions of A. sterilis originated from western Asia (Iran-lraq-Turkey region) were clustered with the cultivated oats A. sativa and A. byzantina, suggesting that A. sativa and A. byzantina might be derived from progenitor germplasm from Iran-lraq-Turkey region. Another wild hexaploid species A. hybrida showed high degree of genetic homogeneity with A. fatua, is better to consider as a subspecies of A. fatua. This research contributes to clarifying the hexaploid origin of cultivated hexaploid oats.