Whole-genome resequencing and RNA-seq analysis implicates GPR75 as a potential genetic basis related to retarded growth in South China carp (Cyprinus carpio rubrofuscus)

The south China carp (Cyprinus carpio rubrofuscus) is an indigenous and important fish species, widely cultured in south China. However, part of individuals experienced retarded growth, the genetic basis of which has yet to be elucidated. In this study, whole-genome resequencing of 35 fast-growing and 35 retarded-growing south China carp were conducted to identify promising genes associated with retarded growth. Twelve candidate SNPs were detected and annotated to the Gpr75 gene, which has been reported to be related with body weight through regulating insulin homeostasis. RNA-seq analysis of muscle suggested that differentially expressed genes were significantly enriched in the insulin signaling pathway. Additionally, the fasting serum insulin level was significantly lower while the blood glucose level was significantly higher in the retarded-growing group. Our preliminary study provides insights into the genetic basis underlying the retarded growth and may facilitate further genetic improvement of south China carp.