软鳍新光唇鱼MC4R基因多态性与生长性状关联性分析

    Polymorphisms of MC4R gene and its association with growth traits in Neolissochilus benasi

    • 摘要:
      背景 软鳍新光唇鱼(Neolissochilus benasi)是重要的水产种质资源,但在培育过程中存在个体间生长速度差异较大的问题。
      目的 筛选与软鳍新光唇鱼生长性状显著相关的分子标记,推动其生长性状的改良。
      方法 本研究对与摄食、能量代谢、生长发育密切相关的黑素皮质素受体-4(MC4R)基因开展研究,通过PCR-Sanger测序技术进行单核苷酸多态性(SNP)检测和分型,并将SNP位点与其生长性状进行关联性分析,挖掘软鳍新光唇鱼生长性状关联的SNP标记。
      结果 MC4R基因2个拷贝共存在15个SNP位点,其中第1个拷贝有1个SNP位点,第2个拷贝有14个SNP位点。15个SNP位点中仅G227A为错义突变,氨基酸类型由缬氨酸(V)变为异亮氨酸(I),其余位点均为同义突变;群体遗传分析结果显示,除第1个拷贝SNP位点G669C 遗传参数值较低外,MC4R基因第2个拷贝的SNP位点期望杂合度 (He)和观测杂合度(Ho)分别为0.860±0.027和0.503±0.001,多态信息含量(PIC)为0.373~0.375,属于中度多态性,表明该群体的遗传多样性处于中上水平;关联性分析显示,MC4R基因2个拷贝15个SNP位点中,13个位点对软鳍新光唇鱼的生长性状具有不同程度的影响:位点G227A、A322G、C364T、G403A、T451C、G457A、G472A、T484C、G520A、T583C、G736A、C775G与体长、体质量显著相关(P<0.05),且均以纯合子为优势基因型,分别为AA、GG、TT、AA、CC、AA、AA、CC、AA、CC、AA、GG型;位点C664T仅检测到CC和CT两种基因型,并以杂合子CT型为优势基因型,与体质量显著相关(P<0.05)。
      结论 本研究初步筛选了15个与软鳍新光唇鱼生长性状相关联的候选SNP位点,为今后其生长相关机制和分子标记的进一步解析,以及生长性状的改良提供了科学依据。

       

      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.

       

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