Genomic and Transcriptomic Profiling of Amino Acid Compositions in Common Carp Fillets

Fish are rich sources of amino acids (AAs), particularly human essential amino acids (HEAAs). Exploring the regulatory mechanisms behind the changes in the combined AA content in the fillet and enhancing the content of AAs, especially HEAAs, in fillets of farmed fish is crucial for meeting human nutritional needs. After hot acidic hydrolysis of 304 common carp fillets, we quantified the contents of 17 single AAs and 5 AA groups and observed significant variations among them. Except for Pro, 16 single AAs and all AA groups showed medium-to-high heritabilities over 0.2. Through a genome-wide association study (GWAS), we identified 1974 SNPs and candidate genes associated with at least one AA content. Using transcriptome data from groups with the highest and lowest contents for each AA, 7089 candidate genes were related to the concentrations of at least two AAs. For the total HEAA content, 121 SNPs and their associated genes preferred ATPase-coupled transmembrane transporter activity, and 4727 differentially expressed genes were enriched in cytokine activity, chemokine activity, oxidoreductase activity, and ion binding. With the optimal genomic selection programs and associated SNPs, the correlation between the actual AA contents and estimated breeding values was high and positive, ranging from 0.76 to 0.90. These findings revealed the major-effect processes and regulatory mechanisms modulating the differences in fillet AA contents. The genomic selection programs will guide the future selection of common carp with high AA contents.