The Establishment Of AFLP Fingerprinting And SNP Markers Screening Associated With Growth Traits Of Gymnocypris Przwalskii

Gymnocypris przewalskii, the naked carp is one of the endangered species in China. The selective breeding of the parent naked carp is the most important work in protection and restoration of wild naked carp. In this thesis, first, the relationships between body weight and related morphological characters were determined. Then, the naked carp groups in different tributaries were analysied by the means of amplified fragment length polymorphism(AFLP) finger printing. Finally, SNP locis were determinded by sequence alignment method, combining with the SNPs locis and morphological characters, three SNPS loci associated with growth traits were screened. Specific contents and results are as follows:In this study, to determine the relationship between body weight and morphological traits, a total amount of 200 2-years-old individuals were sampled for measuring the body wheight and nine metric traits, including the total length, standard length, head length, body height, interorbital width, length before anus, body width, anal fin base. The relationship between morphological characters and body weight was quantified by correlation analysis, multiple regression and path analysis methods. It was showed the correlation coefficient between most morphometric traits and body weight reached extremely significant level(p<0.01). Path analysis showed that the main factor in direct impact on body weight is standard length, followed by body heght and long anal fin base. The morphometric attributes standard length(X2), body height(X5) and anal fin base(X9) were used to establish the multiple regression equations as Y=3.502 X2+11.01 X5+4.188 X9-48.088. According to the regression coefficient test, the influence of standard length, body height and anal fin base on the body weight reached significant level(p<0.05). Multiple correlation analysis showed that the relevant indexs between morphometric attributes and body weight were more than 0.85, the multiple regression equations had goodness fit. Standard length, body heght and long anal fin base should be considered in parental breeding.Amplified fragment length polymorphism(AFLP) was employed to analyze the genetic diversity among populations of scaleless carp(Gymnocypris przewalskii) from different tributaries of Qinghai lake. Ten pairs of Eco RⅠ/MseⅠprimers showing high level of polymorphism and stable band were selected out from 64 primer combinations and used for further practical AFLP analysis. 348 bands were scored, 184 of which were polymorphism with 52.9% of the polymorphic rate. 79 specific fragments were obtained by amplified fragment length polymorphisms(AFLP) technology and AFLP fingerprint was built using ten primer combinations. Naked carp can be distinguished exactly by AFLP fingerprint. We have analyzed the density ions and dissolved oxygen in different tributaries. It revealed that when the genetic similarity coefficient was 0.87, Sha Liu river, Hei Ma river and Gan Zi river went together for a group respectively, Quan Ji river, Bu Ha river and Ha’er gai river for a group.The growth of bony fish is controled by GH/IGF-1 growth axis, growth hormone(GH) is at the core. 200 bp PCR products of growth hormone gene were sequenced to screen genotypes in Gymnocypris Przwalskii by single nucleotide polymorphism analysis(SNP). Three mutation points associated with growth traits were found by correlation analysis, which concluded SNP68, SNP80, and SNP148. The individuals with genotype CC were better than the individuals with genotype CT in body height and body weight at SNP68. The individuals with genotype AA were better than the individual with genotype AT in body weight, body height, standard length and anal fin base at SNP80. The individuals with genotype AG showed more advantages than the individuals with genotype GG in body weight, body height, standard length and anal fin base at SNP148. The results laid foundation for marker-assisted breeding.