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

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.