Quantitative trait loci for morphometric traits in multiple families of common carp (Cyprinus carpio)

Quantitative trait locus (QTL) mapping is frequently used to understand the genetic architecture of quantitative traits. Herein, we performed a genome scan for QTL affecting the morphometric characters in eight full-sib families containing 522 individuals using different statistical methods (Sib-pair and half-sib model). A total of 194 QTLs were detected in 25 different regions on 10 linkage groups (LGs). Among them, 37 QTLs on five LGs (eight, 13, 24, 40 and 45) were significant (5% genome-wide level), while the remaining 40 (1% chromosome-wide level) and 117 (5% chromosome-wide level) indicated suggestive effect on those traits. Heritabilities for most morphometric traits were moderate to high, ranging from 0.21 to 0.66, with generally strong phenotypic and genetic correlations between the traits. A large number of QTLs for morphometric traits were co-located, consistent with their high correlations, and may reflect pleiotropic effect on the same genes. Biological pathways were mapped for possible candidate genes on QTL regions. One significantly enriched pathway was identified on LG45, which had a P-value of 0.04 and corresponded to the "regulation of actin cytoskeleton pathway". The results are expected to be useful in marker-assisted selection (MAS) and provide valuable information for the study of gene pathway for morphometric and growth traits of the common carp.