Association of MyoD1a and MyoD1b gene polymorphisms and meat quality traits in rainbow trout

In this study, we identified myogenic regulatory factors (MRFs) and analyzed the correlation between MRFs and meat quality in rainbow trout. The MyoD1a and MyoD1b genes were cloned from rainbow trout using a homology cloning method. Introns 1 and 2 in the MyoD1a and MyoD1b genes were cloned and submitted to GenBank (accession Nos. FJ623462 and FJ793566). Polymorphisms of MyoD1a and MyoD1b genes were analyzed using single-strand conformation polymorphism and sequencing, respectively. Two single nucleotide polymorphisms were detected in the MyoD1 gene, located at 129G→A in exon 1 and 37 G→A in exon 2. The 37 G→A mutation in exon 2 induced the R185K amino acid change in the polypeptide chain. Seven single nucleotide polymorphisms in the MyoD2 gene were detected, including 218T→C, 224T→C, 242A→C, 246T→A, 248T→C, 305T→C, and 329C→T. The 246T→A mutation in exon 1 induced the R83K change in the polypeptide chain. In the S3 fragment, meat quality traits of genotypes AA and AB significantly differed from those of genotype BB (P < 0.05). In the S5 fragment, meat quality traits of the genotypes AA and AC were significantly different from the genotypes BB and BC (P < 0.05). These results indicate that the MyoD1a and MyoD1b genes have an important influence on meat quality or were linked to the major genes in these strains. These genes can be used to control muscle fiber traits in rainbow trout, and the mutations in the S3 and S5 fragments can be used as molecular markers for selecting rainbow trout with better meat quality traits.