| Yellow Catfish (Pelteobagrus fulvidraco) is a common medium commercial fish with fresh tender meat, delicious taste and high nutritional value, thereby being popular with a host of consumers.The growth of Yellow Catfish present significant gender specificity, of which the male grow faster and larger than the female.As a result,Aquaculture Industry of China is making great efforts to carry out single-sex breeding of Yellow Catfish.In this paper, ISSR and TRAP markers are applied to detect genetic structure and diversity of Yellow Catfish population, with an aim to enhance the protection and the management of germplasm resources of Yellow Catfish and provide genetic backgrounds and theoretical basis related to Yellow Catfish. In addition, the application of ISSR and TRAP markers screening sex determination of female and male catfish-related molecular markers,aiming to greatly improve the selectivity of single-sex breeding orientation of Yellow Catfish and provide scientific basis to enhance the predictability of single-sex breeding of Yellow Catfish.The main work and conclusions of this research are as follows:1.Analysis of genetic diversity of Yellow Catfish by ISSR markers. ISSR markers were used to analyze the genetic diversity of two wild groups of Yellow Catfish (Songhua River group, SH; Heilongjiang group, HL)as well as two breeding groups (Zhaodong groups, ZD; Liaoyang groups, LY).The result indicates that the four Yellow Catfish groups have a high genetic diversity level, of which SH the highest, HL as well as ZD the second, and LY the lowest. Besides, genetic diversity level of wild populations are higher than that of breeding groups.Analysis of genetic variation revealed that the four Yellow Catfish groups exists a certain division, of which differentiation of wild and cultured populations appear significantly.2.Analysis of genetic diversity of Yellow Catfish by TRAP markers.TRAP markers were used to analyze the genetic diversity of wild group(SH)as well as breeding groups (ZD) Yellow Catfish,the result indicates that the two Yellow Catfish group had a high genetic diversity level,and genetic diversity level of wild groups were higher than that of breeding groups.Genetic variation analysis demonstrated that significant differentiation occurred between SH and ZD.Compared with the results of ISSR markers, the results of which were consistent with the findings done by TRAP marker,revealing that both the two Yellow Catfish group had a high genetic diversity level. According to the genetic distance obtained from the two markers, individual phylogenetic tree was constructed. The result demonstrated that the two cluster diagram was similar, thereby the two markers having a certain correlation with each other. Compared with the amount of information, the MI value of TRAP (4.51)is higher than ISSR (2.42), indicating that TRAP marker that has a higher labeling efficiency,and a higher diversity of detection level as well.3.Screening gender-specific markers of Yellow Catfish by using ISSR and TRAP markers. In this study, ISSR and TRAP markers were used to screen sex-specific markers of male and female Yellow Catfish(ZD) obtained from Zhaodong Breeding Farm. Results of ISSR-PCR amplification screened two females gender-specific ISSR markers,UBC835-3 sites were seen expressed in female Yellow Catfish(93.33%) but male Yellow Catfish only 13.33%; in contrast,UBC835-4 sites of expression were seen expressed in all male Yellow Catfish,whereas no expression was seen in female Yellow Catfish.Meanwhile, results of TRAP-PCR amplification presented two gender-specific TRAP markers, ME1-EM1-22 sites and ME2-EM3-8 sites, they were seen expressed in female Yellow Catfish(40%),yet could seen expressed in all male Yellow Catfish.Therefore, these sites can be identified as Yellow Catfish sex-specific molecular markers.
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