| Siniperca chuatsi belongs to Perciformes,Sinipercinae and Siniperca.It is a valuable economic fish in China.The growth rate of Siniperca chuatsi is one of the key factors that determine its production cost and economic benefit in the process of breeding.Genetic breeding of growth traits has become an important means to improve animal growth traits.Fish phenotypic characteristics as the breeding target,combined with molecular markassisted selection(MAS),can shorten the breeding time and improve the efficiency of breeding,and is widely used in the genetic breeding of good traits.However,there are still few reports on the development of molecular markers for growth traits of Siniperca chuatsi and the breeding of new varieties with high growth rate assisted by molecular markers.This study focuses on myostatin(mstn)and mammalian target of rapamycin(mtor)of Siniperca chuatsi.Single nucleotide polymorphism(SNP)markers associated with growth traits are developed to provide an effective and reliable basis for molecular marker-assisted selective breeding of Siniperca chuatsi.In addition,we will detect the SNP marker enrichment of growth hormone(gh)in the breeding process of Siniperca chuatsi “Huakang 2” in the five generations of Siniperca chuatsi,and evaluate the effect of SNP markers on the breeding of Siniperca chuatsi “Huakang 2” in the five generations,so as to provide evidence for the breeding of new varieties of Siniperca chuatsi.The main research results are as follows:1.Screening of SNP markers in mstn and mtor genes of Siniperca chuatsiThe study obtained the mstn gene sequence(3 exons and 2 introns),the coding region and some intron sequences of mtor gene by segmentalized amplification of candidate genes mstn and mtor.A mutation site G→C was found at the 255 th base of the second intron of mstn gene,which was named mstn-in2.There were GG,CG and CC genotypes.A mutation site G→T was found at the 16 th base of the 11 th exon of mtor gene,which was named mtor-E11.There were GG,GT and TT genotypes at this site.A mutation site T→C was found at the 48 th base of the 26 th intron of the mtor gene,which was named mtor-in26.There were three genotypes,TT,TC and CC.Three candidate SNP loci was found in mstn and mtor genes,which can be verified by subsequent correlation analysis with growth traits of Siniperca chuatsi.2.Association analysis of SNP markers in mstn and mtor genes and growth traits of Siniperca chuatsiIn this study,the genetic diversity analysis of the three SNP loci selected from young Siniperca Chuatsi in Guizhou and adult Siniperca Chuatsi in Guangdong was conducted,and all of them showed a moderate polymorphism level(0.25<PIC<0.5),and did not deviate from Hardy-Weinberg equilibrium(P>0.05).According to the marker-trait association analysis,in the population of young Siniperca chuatsi,the average length,body length and body weight of individuals with mstn-in2 locus GG were significantly higher than those with CC genotype(P<0.05).At the mtor-in26 locus and mtor-E11 locus,there were no significant differences in total length,body length,body height,body weight and fatness among individuals of different genotypes.In adult Siniperca chuatsi population,the mean values of total length,body length,body height and body weight of individuals with mstn-in2 locus GG genotype were significantly higher than those of individuals with CC genotype(P<0.05).In mtor-in26 locus,the average length,body weight and fatness of TT genotype individuals were significantly higher than those of TC genotype and CC genotype individuals(P<0.05),and the average body length and height of TT genotype individuals were significantly higher than those of CC genotype individuals(P<0.05).We have screened one SNP marker in mstn and mtor genes respectively that is significantly related to growth traits of Siniperca chuatsi and has high polymorphism,which can be used in marker assisted selection breeding.3.Analysis on the breeding effect of SNP marker in gh gene of Siniperca chuatsi “Huakang2” in the five generationsIn the five generations breeding process of Siniperca chuatsi “Huakang 2”,SNP markers related to growth traits in gh gene developed by our laboratory are used to assist the breeding.From F0 to F4 generations,the polymorphic information content of this marker shows a decreasing trend,and from F0 to F3 show the moderate polymorphism(0.25<PIC<0.5).F4 shows the low polymorphism(PIC<0.25);There was no deviation from Hardy-Weinberg equilibrium in 5 generations(P>0.05).The frequency of dominant genotype AA showed an increasing trend from generation to generation.The frequency of dominant genotype AA in F4 generation was 0.2857 higher than that in F0 generation,and the probability of dominant genotype CC in F4 generation was 0.From the perspective of enrichment of dominant genotypes,Siniperca chuatsi “Huakang 2” has good breeding effect at this site.In conclusion,this study studies the growth traits of Siniperca chuatsi,and develops SNP markers in genes by directly expanding candidate genes.We successfully developed one SNP marker in each of the mstn and mtor genes,those are correlated with growth traits of Siniperca chuatsi and have high polymorphism.Moreover,we have verified that SNP markers related to growth traits in gh gene have better breeding effect in the 5 generations of Siniperca chuatsi “Huakang 2”.In future studies,multiple SNP markers can be combined to assist breeding. |
PDF Full Text Request