Abstract:
Background Neolissochilus benasi is an important aquatic germplasm resource, but there is a problem of large differences in growth rate among individuals during the breeding process.
Objective The study aims to identify molecular markers significantly associated with the growth traits in N. benasi and promote the improvement of its growth characteristics.
Methods The study focused on melanocortin-4 receptor (MC4R) gene, which are deeply related to ingestion, energy metabolism and growth development. Single nucleotide polymorphism (SNP) detection and genotyping were performed using PCR-Sanger sequencing technology, and association analysis was conducted between the SNP loci and growth traits to identify SNP markers related to the growth traits of N. benasi.
Results The results showed that there were 15 SNP loci in the two copies of MC4R gene, with one SNP locus in the first copy and 14 SNP loci in the second copy. Among the 15 SNP loci, only G227A was a missense mutation, with the amino acid type changed from valine (V) to isoleucine (I). The remaining loci were synonymous mutations. Population genetic analysis showed that, except for SNP locus G669C in the first copy with low genetic parameter values, the SNP loci in the second copy of MC4R gene had an expected heterozygosity (He) and observed heterozygosity (Ho) of 0.860 4±0.027 2 and 0.503 2±0.001 4, respectively, and their polymorphic information content (PIC) ranged from 0.3731 to 0.3749, indicating a middle-upper level of genetic diversity in this population. Association analysis revealed that 13 SNP loci in the two copies of MC4R gene had varying degrees of influence on the growth traits of N. benasi: G227A, A322G, C364T, G403A, T451C, G457A, G472A, T484C, G520A, T583C, G736A, and C775G were significantly associated with body length and body mass (P<0.05), with homozygous genotypes AA, GG, TT, AA, CC, AA, AA, CC, AA, CC, AA, and GG being the dominant genotypes, respectively. Meanwhile, C664T was only detected two genotypes (CC and CT), with the heterozygous CT genotype being dominant and strongly associated with body mass (P<0.05).
Conclusion This study preliminarily screens 15 candidate SNP loci associated with growth traits in N. benasi, providing a scientific basis for further analysis of growth-related mechanisms and molecular markers, as well as for the improvement of growth traits in this species.