蚂蚱麦和小白麦衍生系的遗传多样性分析

Genetic diversity assessment in derivative offspring of Mazhamai and Xiaobaimai wheat

陕西关中蚂蚱麦和山西平遥小白麦是我国北方小麦品种的原始骨干亲本,解析蚂蚱麦和小白麦及其衍生系的遗传多样性对于小麦品种改良具有重要的参考意义。本研究利用小麦660KSNP芯片对蚂蚱麦、小白麦及其衍生品种(系)进行全基因组扫描,分析其遗传多样性。结果表明,小麦3个基因组的多态性SNP标记数为B>A>D,第4同源群的多态性标记数最少,149份供试材料基因多样性(H)范围为0.095~0.500,平均值为0.336;核苷酸多样性指数(π)范围为0.272~0.435,平均值为0.340;而遗传相似系数(GS)变幅为0.335~0.997,平均值达0.619,表明蚂蚱麦和小白麦衍生系的遗传多样性较低。聚类分析表明蚂蚱麦和小白麦紧密地聚在亚群Ⅰ,其衍生品种(系)分为5个亚群,其中2000年以前以蚂蚱麦或小白麦的单一衍生系为主,分在亚群Ⅰ、Ⅱ、Ⅲ,2000年以后多数品种同时拥有蚂蚱麦和小白麦血缘,分在亚群Ⅳ、Ⅴ,遗传多样性较高,且与大面积推广品种聚为一类。因此,应加强优异基因资源导入,拓宽小麦品种的遗传基础,最终提高育种水平。

“Mazhamai” originated in Guanzhong region of Shaanxi province,and “Xiaobaimai” in Pingyao county of Shanxi province,two landraces of wheat (Triticum aestivum L.),are the primitive founder parents of wheat cultivars in northern China. The genetic diversity assessment of “Mazhamai”,“Xiaobaimai” and their derivative offsprings will be helpful to wheat cultivar improvement. In this study,a wheat 660K SNP Array was used to perform genome-wide scanning for analyzing genetic diversity of “Mazhamai”,“Xiaobaimai” and their derivatives. The polymorphic SNP marker number in three genomes was B>A>D,and the fourth homoeologous group had the least number of polymorphic markers. The gene diversity (H) and nucleotide diversity (π) ranges were 0.095-0.500 and 0.272-0.435,with corresponding average values of 0.336 and 0.340 in 149 wheat accessions,respectively. The genetic similarity coefficient (GS) ranged from 0.335 to 0.997,with an average value of 0.619 in the wheat panel. It indicated a low genetic diversity in the derivative offsprings of “Mazhamai” and “Xiaobaimai”. Cluster analysis exhibited that the derived cultivars of “Mazhamai” and “Xiaobaimai” were divided into five clusters,“Mazhamai” and “Xiaobaimai” were closely grouped into Cluster Ⅰ. The cultivars released before 2000 were mainly the single derivatives of “Mazhamai” or “Xiaobaimai” in Cluster Ⅰ,Ⅱ and Ⅲ and grouped,while the most cultivars released after 2000 possessed both blood of “Mazhamai” and “Xiaobaimai” with higher genetic diversity than the former,and grouped in Cluster Ⅳ and Ⅴ just like commercial cultivars widely grown. Therefore,we should strengthen the introduction of beneficial genetic resources,broaden the genetic basis of wheat cultivars,resulting in improved breeding level.