玉米S_2和S_4代株系遗传变异研究

Genetic variations of S_2 and S_4 inbred lines in maize

本研究以52个S2和22个S4代株系及其组配的杂交种为材料,利用SSR标记分析不同世代材料间的遗传差异.结果表明,20对SSR核心引物在S2和S4代株系中分别检测到61和39个等位基因变异,每对引物平均检测到3.1和1.95个等位基因以及4.7和2.15个基因型.通过类平均法(UPGMA)将52个S2代株系划分为7大类群,其中A9-22和A9-37单独聚为一类,其余株系类群与系谱来源基本一致;将22个S4代株系划分成4大类群,与系谱来源一致.S2和S4代株系间差异位点数变幅分别为2-37个和0-23个,且系谱来源相同的株系间差异位点数少于其不同来源的株系.证明玉米S2代是急剧分离世代,随着世代的增加,S4代趋向稳定,群体整齐度增高,其相应杂交组合也表现出相似的遗传变异规律.

In the current study,52S2,22S4 lines,and early generation hybrids were subjected to genetic variation analysis by SSR makers.The results showed that 61 allelic variations were detected in S2 by 20pairs of core primers,while 39 in S4,with each pair of primer detecting 3.1and 1.95 alleles,and 4.7and 2.15 genotypes in S2 and S4,respectively.According to the UPGMA,52S2 lines were divided into7 groups,among which A9-22 and A9-37 were grouped separately while the rest were within the similar resource of pedigree;22S4lines were into 4groups,which were consistent with their pedigree.The discrepant sites in S2 and S4lines were 2to 37 and 0to 23,respectively,and the discrepant sites between the lines from the same pedigree were less than those from different pedigrees.It was proved at the molecular level that S2 went sharp separation generation,and with the generation increase,S4 tended to become stable and the population uniformity increased,so did their corresponding hybrid combinations.Thus,in the breeding practice it is beneficial to increase the amount of fine individuals from S2 lines and retain those of different pedigrees in S4 generation.