Identification of quantitative trait loci for abdominal muscle content in red swamp crayfish (Procambarus clarkii) and potential application in molecular breeding.

Red swamp crayfish (Procambarus clarkii) is a prized aquatic product among consumers, abdominal muscle content being a crucial economic trait. Therefore, there is an urgent need to exploit the genetic basis of crayfish abdominal muscle content for breeding. In the present study, Quantitative Trait Locus (QTL) mapping was performed using 10 different populations (Pop1-Pop10), raised in water tanks, ponds, and rice-crayfish fields, using single- and multiple-culture models of full-sib families and natural populations, from 2020 to 2023. In total, 22 QTLs for abdominal muscle content were identified with population repetitions, explaining the phenotypic variation in the range of 2.7 %-21.3 %, six of which were heterosis sites. Additionally, nine of the 22 QTLs had the consistent genotype with phenotypic effect in eight natural populations (Pop3-Pop10), where the proportion of genotypes with phenotypic effect of the QTL for abdominal muscle weight / body weight (MW/BW) and chelae weight / body weight (CHW/BW) in the group including the top 10 % of the yield of abdominal muscle content individuals (High group) was significantly higher than that in the group including the bottom 10 % of the yield of abdominal muscle content individuals (Low group), respectively (P < 0.01). These results suggest that the QTLs identified repeatedly, especially the nine QTLs, are reliable candidate loci for abdominal muscle content, which is immensely important for the genetic analysis of abdominal muscle content in red swamp crayfish and molecular marker-assisted breeding.