Molecular characterization and SNPs association with growth‐related traits of myosin heavy chains from the pearl oyster Pinctada fucata martensii

Myosin heavy chains (MYHs) are important proteins in muscle growth and contraction, which may potentially enhance shellfish growth. In this study, the MYH gene from Pinctada fucata martensii (PmMYH) was studied. Sequence analysis revealed that it has an open reading frame of 5823 bp that encode 1940 polypeptide residues. Analysis of PmMYH showed four conserved domains, namely Myosin_N, MYSc, IQ and Myosin_tail_1. Blast analysis confirmed that PmMYH has a high identity with MYH protein sequences from Crassostrea virginica (87.25%), C. gigas (86.15%), Biomphalaria glabrata (78.8%), Pecten maximus (77.15%), Mizuhopecten yessoensis (75.78%) and Argopecten irradians (77.30%). Expression pattern analysis of PmMYH demonstrated that it is widely expressed in tissues and developmental stages, especially in the adductor muscles and late development stage. Furthermore, PmMYH also expressed significantly higher in individuals selected for fast growth compared with those selected for slow growth, thereby suggesting its role on growth-related traits. Ninety-five single nucleotide polymorphisms (SNPs) were identified in the exon region of PmMYH, and 18 of which were significantly associated with growth (p < 0.05). Of the 18 SNPs, 2 were also verified in two independent populations. Therefore, PmMYH and its SNPs could be used as for the gene-assisted selection of P. f. martensii.