青鱼生长QTL紧密连锁分子标记与生长性状的关联分析

CORRELATION ANALYSIS OF GROWTH QTL TIGHTLY LINKAGE MOLECULAR MARKERS AND GROWTH TRAITS IN BLACK CARP (MYLOPHARYNGODON PICEUS)

  • 摘要: 研究对前期建立的青鱼(Mylopharyngodon piceus)家系高密度遗传连锁图谱及体长QTL的定位结果进行深入分析, 在10号连锁群上识别到与体长相关的QTL区域, 存在2个与体长强烈相关的紧密连锁SNP位点。研究利用特异性标记判定青鱼遗传性别, 对SNP位点侧翼序列PCR扩增子进行sanger测序。得到准确的SNP位点基因型信息后, 研究对紧密连锁SNP位点不同基因型与邗江青鱼群体生长性状进行了细致的关联分析。结果表明, 在563尾邗江青鱼群体中, 雌鱼290尾, 雄鱼273尾, 雌雄比约为1.06﹕1。遗传分析显示, SNP7957G>C和SNP9802T>A有效等位基因数(Ne)分别为1.754和1.399, 观测杂合度(Ho)分别为0.384和0.266, 期望杂合度(He)分别为0.430和0.285, 多态信息含量分别(PIC)为0.508和0.378。相比雄鱼, 雌鱼生长速度更快, 但是变异系数更高, 说明雌鱼生长性状离散程度更大。SNP7957G>C和SNP9802T>A不同基因型在群体体长性状中存在显著差异。SNP7957G>C位点的GG基因型在雄鱼体长性状中具有显著优势(P<0.05), SNP7957G>C和SNP9802T>A单标记其他基因型与生长性状之间存在差异, 但未达到统计学差异。在SNP位点不同基因型构建的二倍型中, 雌雄个体表现出一定的生长差异, D8(GGTA)在生长方面具有显著优势 (P<0.05), 具有一定育种价值。研究结果可为选育快速生长青鱼新品种提供分子标记, 为未来青鱼遗传改良和分子标记辅助育种策略提供科学依据。

     

    Abstract: In this study, leveraging the high-density genetic linkage map and growth QTL mapping outcomes established in the prior phase for black carp (Mylopharyngodon piceus), two SNPs loci were identified as correlated with growth traits within the Hanjiang population of black carp. These loci were situated on LG10 (linkage group) and closely associated with a specific growth QTL. Sex-specific markers were devised for sex determination. Subsequently, SNP polymorphisms were assessed through direct sequencing, and the association degree of different genotypes with male and female growth traits was scrutinized. The results showed that among the 563 individuals in the Hanjiang black carp population, there were 290 females and 273 males, with a female-to-male ratio of approximately 1.06:1. Genetic diversity analyses showed that the effective number of alleles (Ne) was 1.754 and 1.399, observed heterozygosity (Ho) was 0.384 and 0.266, expected heterozygosity (He) was 0.430 and 0.285, and polymorphic information content (PIC) was 0.508 and 0.378 for SNP7957G>C and SNP9802T>A, respectively. Compared to males, females exhibited faster growth rates, albeit with higher coefficients of variation, indicating greater variability in females growth traits. Genotypes of SNP7957G>C and SNP9802T>A displayed significant disparities in body length traits within the black carp population. The SNP7957G>C GG genotype notably dominanted (P<0.05) in male body length traits, while variations in haplotypes between SNP7957G>C and SNP9802T>A showed distinctions in growth traits, albeit not reaching statistical difference. Among diplotypes constructed from the two SNP loci, males and females showed dissimilarities in growth, with D8 (GGTA) notably superior in growth traits (P<0.05). The results of this study provide potential molecular markers for selective breeding of new fast-growing black carp varieties and establish a theoretical foundation for the in-depth exploration of growth traits fine mapping in black carp, along with QTL tightly linked marker assisted selected breeding.

     

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