Construction Of A High-Density Genetic Linkage Map And Fine Mapping Of Qtls For Growth And Sex-Related Traits In Red-Tail Catfish (Hemibagrus Wyckioides)

High-density genetic linkage map based on single nucleotide polymorphisms (SNPs) are essential for fine mapping of QTLs and identification of trait-related genes in aquaculture fish species. In this study, the first high density genetic linkage map of red-tail catfish (Hemibagrus wyckioides) based on 2b-RAD sequencing technology was constructed using one F1 family composed of 165 offspring and their parents. A total of 2369 SNP markers were assigned to 29 linkage groups (LGs) and the map spanned 2067.35 cM with an average SNP marker interval of 0.87 cM and genome coverage of 98.16%. QTL mapping analysis revealed that 2 significant and 15 suggestive QTLs for all four morphometric traits were identified on 10 LGs, explaining 7.4-13.3% of phenotypic variations. Some candidate growth-related genes such as ttc39b, lrp1, gng3, aspp2, mgp and rusc2 were identified within QTL intervals, and a SNP in ttc39b was found to be significantly associated with body weight in different genetically unrelated populations of red-tail catfish. In addition, one genome-wide significance sex-related QTL was detected on the LG20 with a contribution to phenotypic variation of 44.2-85.7%. A total of 10 potential sex dimorphic genes, such as vps54, tsg10, pld6, psmd8 and gpa33, were also identified within or near the sex QTL markers in LG20. It suggests that the LG20 may be a sex-related LG in red-tail catfish. This high-density genetic map not only enables us to fine-map these genes related with the economic traits, but also provides effective information for future marker-assisted selection and sex-control breeding in this species.