3个不同玉米基础群体及其改良后代遗传变异的SSR分析

基于微卫星(SSR)标记的遗传参数评估,分析了3个玉米人工合成群体GP3、GP4和GP5及其经2轮、4轮控制双亲混合选择改良后代的遗传变异。结果表明:40对SSR引物在基础群体及其改良后代中共检测到287个多态性位点,每个SSR标记的等位基因数为4～12个,平均7.18个;群体GP3及其改良后代的多态性位点数略高于GP4、GP5及其相应的改良后代,GP3、GP5群体随改良代数增加其多态性位点数呈略增趋势;群体GP3和GP4改良后代的群内遗传相似系数呈渐增趋势,而GP5则变化不大;GP3和GP4的群体基因型数随改良代数增加呈略减趋势,GP5呈略增趋势;GP3群体改良后代的遗传多样性指数变化呈下降趋势,GP4和GP5群体改良后代的变化呈上升趋势;3个群体的群内遗传变异均明显大于群间遗传变异;群体GP3的有效等位基因数为先减后增,GP5为连续略增,GP4呈略减趋势;群体GP3、GP5改良后代的实际基因杂合度和有效基因杂合度无明显变化,而GP4改良后代的变化呈略减趋势。

Genetic Variation of Population Improvement by Mass Selection on Three Different Synthesized Maize Groups Based on SSR Data

In present study, based on genetic estimate evaluation with microsatellite (SSR) markers, the genetic variation of population improvement by mass selection for two and four cycles on the three synthesized maize groups GP3, GP4 and GP5 were analyzed.Using 40 SSR loci distributed on 10 chromosomes of maize, 287 alleles were de-tected among the groups.At each locus, the number of alleles varied from 4 to 12, with an average of 7.18.The poly-morphic alleles in group GP3 and its derivative were a little higher than those of GP4, GP5 as well as their derivatives, respectively.The polymorphic alleles in the derivatives of GP3 and GP5 exhibited an increase.For the genetic simi-larity coefficients among populations, the derivatives of GP3 and GP4 increased gradually and there existed no change in those of GPS.The genotypic numbers in the derivatives of GP3 and GP4 showed a decreasing tendency while a little increase was found in those of GP5.In comparison with their primary group, the genetic diversity indexes in the derivatives of GP3 decreased while those of GP4 and GP5 increased gradually.Considerable genetic variation revealed within rather than among the group.The effective allelic number A_e in the derivatives of GP3 decreased, and then in-creased.Gradually increased and decreased A_e were found in GP4 and GP5, respectively.For estimates of the ob-served heterozygosity H_o and expected heterozygosity H_e, the derivatives of GP3 and GP5 showed no differences and those of GP4 exhibited a little decrease.