Study On The Interspecies-specific ISSR Markers And Genetic Diversity Of Two Coreius Fishes In The Upper Reach Of Yangtze River

This study chose two species of Coreius in the upper reach of Yangtze River, the Coreius heterodon(Bleeker) and Coreius guichenoti(Sauvage et Dabry), screening the interspecies-specific ISSR (Inter simple sequence repeats) marker between them, for providing a new, more convenient and precise molecular biological method to discriminate those two species and their ichthyoplankton, so as to offer new technical support and foundation for studying the biology and ecology of fishes with pelagic eggs in the upper reach of Yangtze River. Meanwhile, in order to provide the comparable data for studying the changes of hereditary constitution and mechanism to adapt the environment of those two species, this study also analyzed their population genetic diversity and genetic differentiation by using ISSR markers, offering more information to reveal the current situation of the genetic diversity of those two species.At the beginning, there were 90 young C.heterodon and C.guichenoti collected from Hejiang, Mudong and Fengdu in the upper reach of Yangtze River from April to May in 2009, with 30 samples of each species at every sampling site. According to the results of ISSR-PCR of the nuclear DNA of the two species, there were 3 interspecies-specific ISSR primers obtained by screening the total of 100 ISSR primers, they're UBC835, UBC836 and UBC861. As to C.heterodon, the PCR produces of those 3 primers showed 5 species-specific electrophoresis strips in the electrophoretogram, named TYUBC835-600, TYUBC836-240,540,620, TYUBC861-520; while to C.guichenoti, there're 7 species-specific electrophoresis strips, named YKUBC835-1000,1400; YKUBC836-570,680; YKUBC861-460,800,1200。The results indicated that, the interspecies-specific electrophoresis strips of C.heterodon and C.guichenoti gained by ISSR molecular technique can be useful to discriminate two fishes of Coreius(C.heterodon and C.guichenoti). In order to verify if the results gained in young fishes above can be used in ichthyoplankton of fishes in Coreius, ichthyoplankton probably identified as Coreius by their morphology were selected, and their nuclear DNA were amplified with the 3 ISSR primers mentioned above. The results showed that, there're the same 5 species-specific electrophoresis strips in the electrophoretogram of 5 ichthyoplankton samples as in the young C.heterodon, it reaveled that they're might be C.heterodon.On the other hand, for evaluating the genetic diversity of C.heterodon and C.guichenoti, the numbers of electrophoresis strips which were produced by the PCR of young C.heterodon and C.guichenoti's nuclear DNA using the 3 ISSR primers were statisticsed and analyzed. According to calculate the values reflecting the genetic diversity and compared these values to the results from the same kind of researches, it was showed that the genetic diversity of those two species was in a relative high level and didn't influenced significantly by the change of the environment. The cluster analysis of the two species were carried out by using the genetic distances among the 3 geographic populations of each species, the results showed that, although there're both two branches of the geographic populations of the two species, the UPGMA trees were different which could be related to the survival rate of the ichthyoplankton from upper reach of Yangtze River and the adaptability of those two species. Meanwhile, the Fst value and AMOVA of C.heterodon and C.guichenoti revealed no genetic differentiation between the 3 geographic groups of each species.