Analysis of Genetic Structure and Relationships of Maize Inbred Lines in China

Based on molecular marker data from 112 microsatellites, the genetic structure of 97 maize inbred lines was analyzed using distance-based and model-based clustering methods. The dendrograms produced by both methods showed similar categories but the model-based dendrogram sorted the uncertain lines in the distance-based cluster tree, which provided reasonable explanation of the category. The analysis of genetic structure and model-based cluster showed that the 97 inbred lines were classified into 4 subpopulations, which were known as Reid, Lüda Red Cob (LRC), PB, and Sipingtou (SPT). Many inbred lines in a subpopulation contained certain genetic component from other subpopulations. According to Nei's genetic distance, the Reid subpopulation was the closet to the LRC subpopulation and the farthest to the SPT subpopulation. For simplifying the heterotic groups, the subpopulations Reid and LRC could be integrated into one group, or even Reid, LRC, and PB could be integrated into one group.

摘 要玉米自交系遗传关系和遗传结构的解析, 对自交系类群划分和杂交组配具有重要的指导意义。本文选用玉米基因组的112个SSR标记对我国97个玉米自交系进行遗传关系和遗传结构分析, 并评价了遗传距离聚类和模型聚类方法在玉米自交系遗传关系研究中的应用价值。结果表明, 模型聚类方法更适于玉米自交系的遗传关系研究。解析自交系的遗传基础发现, 各类群中均有大量自交系含有其他类群的遗传成分。根据模型聚类结果, 97个自交系被划分为PB、Reid、塘四平头和旅大红骨4个类群。Reid群与旅大红骨群的遗传关系最近, 与塘四平头群遗传关系最远。为了实现杂种优势模式的简化, 4个类群可被简化为3大种质类群[A(旅大红骨群与Reid群)、B(PB群)、C(塘四平头群)], 或2大种质类群[A(旅大红骨群、Reid群、PB群)、B(塘四平头群)]。研究结果为自交系的改良和利用及杂种优势模式确定提供了理论基础。