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用8对微卫星对草鱼长江群体和珠江群体的2个自繁组合:长江♀×长江♂(YY)、珠江♀×珠江♂(ZZ),1个杂交组合:长江♀×珠江♂(YZ),进行遗传多样性和遗传结构分析。8个微卫星位点的等位基因数为2～6个,并具有较好的多态性,可以用于遗传变异分析。有效等位基因数、观测杂和度、期望杂合度、多态性息含量均以YZ组合最高,分别为2.8111、0.9843、0.6399、0.5598;ZZ组合最低,分别为2.6751、0.8650、0.6129、0.5283;YY组合介于两者之间。基于Nei’s遗传距离构建的UPGMA和NJ系统树揭示YZ组合与YY组合亲缘关系更近。组合间遗传分化分析(Fst)及AMOVA分析表明,YY组合与ZZ组合间达到中等遗传分化水平(Fst=0.0860,P<0.01)。结果表明:杂交后代遗传变异水平显著提高,具有较高的选育潜力;长江与珠江水系草鱼存在一定程度的遗传分化。
Eight self-propagating combinations of grass carp Yangtze River population and Pearl River population were obtained from eight pairs of microsatellites: Yangtze River ♀ × Yangtze River ♂ (YY), Pearl River ♀ × Pearl River ♂ (ZZ), and one hybrid combination: Yangtze River ♀ × Pearl River ♂ (YZ) , For genetic diversity and genetic structure analysis. The 8 microsatellite loci had 2 to 6 alleles and had good polymorphism, which could be used for genetic variation analysis. The number of effective alleles, observed heterozygosity, expected heterozygosity and polymorphism information content were the highest in YZ combinations, which were 2.8111,0.9843,0.6399,0.5598 respectively; the lowest in ZZ combinations were 2.6751,0.8650,0.6129,0.5283 respectively; YY combination between the two. The UPGMA and NJ phylogenetic trees based on Nei’s genetic distance revealed that the YZ combination is more closely related to the YY combination. The results of Fst and AMOVA showed that the combination of YY and ZZ reached the level of moderate genetic differentiation (Fst = 0.0860, P <0.01). The results showed that the genetic variation of hybrid progenies was significantly increased and had high potential for breeding. The grass carp of the Yangtze River and Pearl River had some degree of genetic differentiation.