Research On Karyotype And Genetic Diversity Of Leptobotia Taeniops

Leptobotia taeniops is a characteristic Chinese freshwater fish species, which is demersal fish with small size. The meat is fresh, rich in nutrition and gorgeous in its body colour. It is also with high economic value and ornamental value. In this thesis, the karyotype of Leptobotia taeniops was studied through the chromosome preparations which obtained from the head and kidney of Leptobotia taeniops in the Tongling section of Yangtze River by the method of injecting PHA (phytohaemagg lutinin) and colchicines the genetic diversity of two sub groups in different colour of the Leptobotia taeniops was studied by using the mitochondrial DNA control region and ISSR(Inter-simple sequence repeat) techniques. The results were as follows:1. The total chromosome number of the fish is50, the karyotype formula is2n=6m+10sm+8st+26t, and NF=66.2. From the research about the sequence polymorphism of mt DNA D-loop sequence of the Leptobotia taeniops by the methods of PCR (Polymerase Chain Reaction) and DNA sequencing, we gained961bp of mt DNA D-loop sequence for analysis. Both18mutations of nucleotide acids and14haplotypes were found in the27sequences of mt DNA D-loop sequence. The haplotypic diversity and the nucleotide diversity of the27individuals was0.8661and0.0038. The average genetic distance between the haplotypes was0.0052.The haplotypic diversity and nucleotide diversity of sub-group Q were0.818and0.0037, and its genetic distance was0.0037the haplotypic diversity and nucleotide diversity of sub-group S were0.9000and0.0042, and genetic distance was0.0041, the Gst between two groups was0.0068. The results indicated that the genetic diversity in mt DNA D-loop in the Leptobotia taeniops is low. The genetic diversity of sub-group S was a litter higher than sub-group Q, and the degree of genetic differentiation between populations is also not high.3. After analyzed the genetic diversity of the total of74individual of two sub group of Leptobotia taeniops by using the11selected ISSR primers, it could be found that gene diversity and shannon information index were0.1276and0.2129and the proportion of polymorphic loci in the overall level of the groups was60.56%Gene diversity and shannon information index in subgroup Q were0.1051and0.1794, and its proportion of polymorphic loci was53.52%Gene diversity and shannon information index in subgroup S were0.1298and0.2135, and its proportion of polymorphic loci was56.34%. The results showed that the genetic diversity of Leptobotia taeniops population is low. The genetic diversity of sub group S slightly higher than sub group Q. Genetic distance between the two sub-groups was0.0218. The Gst was0.0752. The result shows that genetic differentiation among sub groups was not high and they had a relatively closer affinity.This study enriched the cytogenetically parameter of Leptobotia taeniops, and offered some corresponding technical parameters for population quality testing of Leptobotia taeniops. It could not only provide a theoretical basis for protecting germ plasm resource, phylogeny, evolutionary status and biochemical and genetic research of Leptobotia taeniops, but also supply the technical design thought for the domesticating and breeding of Leptobotia taeniops.