GENETIC DIVERSITY OF ARTIFICIAL GYNOGENETIC SILVER CARP AND RAPD ANALYSIS OF INCORPORATION OF HETEROLOGOUS GENETIC MATERIALS IN GYNOGENETIC PROGENY

Silver carp(Hypophthalmichthys molitrix)is one of the most important fresh water farmed fish in China. The seedings of silver carp for aquaculture have come from the Yangtze River because germplasm resources of silver carp is superior to those from other rivers. But advanced biological characteristics for aquaculture germplasm of silver carp was obviously decreased during past years after multigenerations artificial propagation. Their growth became slowly and ability of antidisease reduced. Therefore,it is necessary to breed new strain or variety of silver carp by selecting breeding. Artificially induced fish gynogenesis is one of major manners of selecting breeding. In the present study,gynogenesis of one individual of silver carp from the Yangtze River was induced by heterologous sperms in 1987. We had gained artificial gynogenetic silver carp of two continued generations for ten years. Genetic diversities were analyzed in artificial gynogenetic silver carp in continued two generations,and incorporation of heterologous genetic materials in gynogenetic progenies was studied by RAPD. The results showed that genetic similarity of individuals was 0.945-0.995 among 18 individuals of gynogenetic F 1 progenies by 23 different primers,the average was 0.972. The average of proportion of polymorphic loci was 13.68%in gynogenetic F1 progenies. Index of genetic diversity in gynogenetic F1 progenies was 0.175. There were no significant difference in genetic diversity between common artificial propagated silver carp and gynogenetic F1 progeny. Genetic similarity of individuals was 0.961-1.00 among 15 individuals of gynogenetic F2 progenies by 15 different primers,the average was 0.9852. The average of proportion of polymorphic loci was 9.74%among them. Index of genetic diversity in gynogenetic F2 progeny was only 0.062. According to the genetic similarity and distance,15 individuals of gynogenetic F2 progeny were approximately divided into two strains. The genetic similarity was 1.00 among strain,the genetic similarity was 0.9773 between two strains. The experiment showed that genetic diversity of gynogenetic F2 progeny was significantly decreased after two continued generation gynogenesis. Individuals from gynogenetic F2 progeny of silver carp,common silver carp in the Yangtze River and male common carp(Cyprinus carpio L. )were analyzed using RAPD by 44 different primers. The results indicated that clear RAPD bands were all produced among 42 primers except 2 primers. There were a few alike RAPD special bands that were detected in gynogenetic silver carp and male common carp among 10 primers,but not detected in common silver carp of the Yangtze River. In addition,there were exclusive RAPD bands in gynogenetic silver carp among the other 12 primers. Therefore,it was obvious that heterlogous genetic material had been entered gynogenetic silver carp.