Polymorphism amongst several CPA4 gene sequences and correlation analysis of growth traits in grass carp

[Objective]Many SNP sites regarding the growth of grass carp were screened to provide a theoretical reference for grass carp molecular breeding.[Method]Primers were designed from CPA4 gene cDNA sequences belonging to digestive enzymes from EST database of grass carp.cDNA sequences,expected to contain SNP sites,were amplified and sequenced by direct sequencing of PCR product,and new SNP sites were also targeted.[Result]It was found that expected SNP sites didn't exist.Two nucleotide mutations were identified in 40th and 241th basic group of intron 3 by using direct sequencing and blasting,which were named as 40G and G241T.The polymorphisms were genotyped by CRS-RFLP methods.The percentage of AA,AG,and GG genotype in A40G site was recorded as 50.3,23.8 and 25.9%,respectively.The percentage of GG,GT,and TT genotype in G241T was recorded as 48.6,47.9,and 3.5%,respectively.A general linear model(GLM) was used to statistically analyze the relationship between two SNP sites and major growth traits.The result indicated that in A40G site individuals from GG genotype were higher than AA and AG genotype in terms of body weight,length and height,however,there was no significant difference(P0.05).In G241T site,individuals from TT genotype were the heaviest,and the ones from GG genotype were the lightest,but there was no significant difference(P0.05).There was no significant difference in body weight,length and height etc.of 7 douple-type individuals from A40G and G241T.[Conclusion]Two SNP sites found in intron 3(A40G G241T) from the CPA4 gene in grass carp were divided into three genotypes,nevertheless,various genotypes of the two SNP sites and their double types were not significantly associated with essential growth indices of grass carp.