Polymorphism in the Growth Hormone Gene and Its Association With Growth-Related Traits in Common Carp, Cyprinus carpio (Linnaeus, 1778), in the Inland Saline Production System

Identification of polymorphism in growth-related genes and their association with growth traits is an area of intense research. The growth rate is the most sought-after economic trait in the breeding program of fish. The significant association of polymorphism will aid in marker-assisted selection and speed up the genetic improvement program. The present study was performed in a population of common carp belonging to an ongoing selective breeding program at ICAR-CIFE, Rohtak Center. A total of 50 common carp based on the breeding value for body weight were selected and bifurcated into two groups: high and low performers. Each fish had three records (based on pond age) for growth-related traits, viz., body weight (Bw), body length (Bl), and body height (Bh). At 200 days of pond age, the mean Bw, Bl, and Bh for high performers was 494.28 ± 52.12 g, 23.764 ± 0.63 cm, and 9.36 ± 0.35 cm, respectively, whereas the mean Bw, Bl, and Bh for low performers was found to be 165.72 ± 17.31 g, 16.20 ± 0.57 cm, and 6.40 ± 0.23 cm, respectively. The DNA was extracted from the fin clips of these fish. Five primers were used to amplify five distinct regions of the growth hormone gene covering five exons and four introns. The positive PCR products were purified and subjected to Sanger sequencing. The sequences with a Phred quality score above 20 were imported in Sequencher V for SNP hunting. Five polymorphic sites were detected, viz., C165 (amplicon 3), D60 (amplicon 4), D114 (amplicon 4), E90 (amplicon 5), and E185 loci (amplicon 5). The population genetic analysis was performed using GenAlex V. The D60 and E185 loci significantly deviated from the Hardy–Weinberg equilibrium (p < 0.05). Growth association was performed for the polymorphic loci using a linear model by invoking PROC GLM in SAS. The loci C165, D60, and E90 were significantly associated with the Bw, Bl, and Bh. The results obtained in this study must be utilized in the ongoing selective breeding of common carp to speed up genetic improvement.