玉米SSR标记杂优类群划分及群体遗传结构分析

Analysis of Population Genetic Structure of Maize by SSR Marker and Heterotic Grouping

分析玉米自交系的遗传多样性和群体的遗传结构，可以为优势杂交种的配制提供理论依据。本实验利用筛选后均匀分布在玉米基因组上的70对SSR引物对96份来自平凉育种站的玉米自交系和6个国内通用的标准测验种进行遗传多样性分析，从而划分杂种优势群。针对目标群体，使用Structure2．3．1软件，设定亚群数目（K）为1～9，并假定标记位点都是独立的，利用△K（k）确定最适合的K值，生成Q-matrix，进而对群体遗传结构进行评估。研究结果表明，供试材料中有213个等位基因变异，每对引物检测出等位基因数2～7个，平均3．610个。多态性信息量变化范围0．216～0．846，平均0．614。102个玉米自交系间的遗传相似系数，范围在0．282～0．882，平均0．670。用UPGMA方法进行聚类分析，102份玉米自交系划分为6个杂种优势群，合并后为SS（旅大红骨、PA、Reid）和NSS（PB、四平头、Lancaster）两大种质类群。群体结构评估表明，最合适的K值=7，即目标群体中存在7个亚群。研究结果为选配新杂交组合提供了理论依据。

This study was carried out to analyze the genetic diversity of maize inbred lines and to study genetic structure of germplasm population in order to provide the theoretical basis for preparing dominant hybrid seed. Simple sequence repeat （SSR） analysis of the 70 loci distributed uniformly throughout the maize genome was used to detect genetic variation among 96 maize inbred lines and 6 testers. The population genetic structure was assessed by using Structure2.3.1 software. Setting subsets（K） for 1 -9 ,using AK（k） to determine the most suitable value of K, and then to generate the Q-matrix. Seventy loci identified 213 polymorphic bands. The average number of allele per SSR locus was 3.610 with a range from 2 to 7. The polymorphism information content（PIC） for the SSR loci varied from0. 216 to 0. 846 with an average of 0. 614. Genetic similarities among the materials in this study ranged from 0. 282 to 0. 882 with an average of 0. 670. The inbred lines could be classified into 6 clusters by UPGMA （unweighted pair group method arithmetic average） which could be simplified into SS （ LRC, PA, Reid） and NSS （ PB, SPT, Lancaster） heterotic groups. Assessment of population structure showed that the most appropriate K = 7, namely, there were 7 sub-groups in the target population. The defined population analysis of inbred lines provided the basis for selecting new hybridization combinations.