Study On Microsatellite Markers Of Artificial Gynogenetic Silver Carp (Hypophthalmichthys Molitrix) And Inbreeding Progeney

Silver carp (Hypophthalmichthys molitrix) is one of mainly freshwater cultured fish, which occupies important status in fresh water aquaculture in China. At the present, environment pollution and lacking of scientific techniques of seed selected and protection lead to germplasm of silver carp degeneration. Therefore, it is necessary to breed new stains that have a good economic characteristic which is grow fast, strong disease tolerance and so on. Artificial gynogenesis is an effective method of constructing homozygote quickly, which is used to select choiceness breed. Since 1987, Yangze river fisheries research institute have started to select choiceness breed of artificial gynogenetic silver carp by technology of artificial gynogenesis and sex transformation, and obtained three successive generation artificial gynogenetic silver carp. In this study, microsatellite marker analysis of artificial gynogenetic silver carp and inbreeding progeny by microsatellite primers of silver carp, and Yangze wild silver carp, cultured silver carp, male carp as contrast. The result is as follow.(1) Genetic diversity of three successive generations artificial gynogenetic silver carp (CSC G₃) analyzed by 12 pairs of polymorphism microsatellite primers, and Yangze wild silver carp, cultured silver carp, male carp as contrast. We statisticed genetic parameter of three silver carp populations, which suggested that the average allele number, the average expected heterozygosity (He), the average observed heterozygosity (Ho), the average Shannon index of three silver carp populations is 1.75～4.3, 0.1447～0.7561, 0.1146～1.9833, 0.2486～1.2807 respectively. These dates showed genetic diversity of artificial gynogenetic silver carp G₃ is lower than between cultured silver carp and Yangze wild silver carp and genetic diversity of cultured silver carp is lower than Yangze wild silver carp. We analyzed UPGMA of 22 individuals of artificial gynogenetic silver carp, found that the genetic distances of artificial gynogenetic silver carp G₃ between individuals is very low, genetic similarity is very high, the genetic distance of majority individuals of artificial gynogenetic silver carp G₃ is 0, which indicated that progeny of artificial gynogenetic silver carp is much more homologous and maintaining high homology after three successive generations artificial gynogenetic.(2) Genetic diversity of inbreeding F₂ progeny of artificial gynogenetic silver carp analyzed by 17 pairs of polymorphism microsatellite primers, and Yangze wild silver carp, cultured silver carp, male carp as contrast. The number of allele,genetic heterezygosity and genetic variation of three silver carp populations were calculated and showed that the average allele number, the average heterozy-gosity expected (He), the average observed heterozygosity (Ho), the average genetic variation index of three silver carp populations is 2.1～4.0, 0.2762～0.9588, 0.2774～0.7360, 0.4500～1.2258 respectively. The the average allele number, the average heterozy-gosity expected (He), the average observed heterozygosity (Ho), the average genetic variation index of inbreeding F₂ progeny of artificial gynogenetic silver carp was lower than others. The results of this study showed that genetic diversity of inbreeding F₂ progeny of artificial gynogenetic silver carp was obviously lower than others and inbreeding F₂ progeny keeps high homogeneity. By means of artificial gynogenesis and inbreeding technology may decrease genetic diversity. The relationships among four populations are shown clearly in UPGMA tree. Genetic distance analysis showed that genetic distance between inbreeding F₂ progeny of artificial gynogenetic silver carp and other populations is higher than genetic distance between Yangtz wild silver carp and cultured silver carp, it is show that artificial gynogenetic and inbreeding can bring to change genetic structure of population.(3) Analysis of inbreeding progeny of artificial gynogenetic silver carp by microsatellite marker, it is show that diversity of artificial gynogenetic silver carp is lower than contrastive population. So, artificial gynogenesis is an effective method of constructing homozygote quickly. Meantime, this study will provide theory of seed selected and protection.