Novel SNPs in the 3′UTR Region of GHRb Gene Associated with Growth Traits in Striped Catfish (Pangasianodon hypophthalmus), a Valuable Aquaculture Species

Abstract

The striped catfish, Pangasianodon hypophthalmus is an important freshwater aquaculture species in Southeast Asian countries due to its rapid growth. The growth hormone receptor (GHR) is a significant regulatory factor for the growth axis and has great potential applications in animal genetic breeding. This study aims to characterize the GHRb cDNA of the striped catfish and analyze the distribution of its mRNA. Screening of single nucleotide polymorphisms’ (SNPs) loci and diplotypes was performed to provide basic information for the assisted selection of molecular markers in genetic breeding. The results showed that the GHRb cDNA of striped catfish had 2791 bp, which encoded for 569 amino acids. In a phylogenyic study, the ghrb of the striped catfish was clustered with those of other catfish and they were highly homologous. Quantitative real-time PCR (qRT-PCR) experiments showed that GHRb mRNA was expressed in ten different organs of the striped catfish, with the highest expression level in the liver. Five SNP and a haplotype block were identified in the 3′UTR of the GHRb gene using the direct sequencing of 307 individuals. Three haplotypes were found and four diplotypes were constructed. The association analysis revealed that these polymorphisms were significantly associated with growth traits in the striped catfish (p < 0.05). These polymorphisms will provide a valuable reference for future molecular genetic marker-assisted breeding of striped catfish.