Objective Correlation between the variation sites on the multiple epidermal growth factor-like domains protein 9 gene (EGFL9) and the growth of Ictalures punctatus was investigated.
Method The targeted gene sequencing of EGFL9 was performed to identify the variation sites by alignment with the reference genome. Correlation between the sites and the growth traits of the fish was statistically analyzed.
Result There were 27 sites with polymorphic variations on EGFL9 with 22 effective mutations obtained after filtering. Among which, 4 sites, i.e., g.142, g.573, g.3079, and g.7409, were significantly associated with the growth traits of channel catfish. The SNP sites, g.142, g.3079, and g.7409, were in introns, while the InDel site, g.573, in exon 2. The mean body length of the fish with A/A type at g.142 was significantly longer than that of fish with A/G type (P＜0.05), while that of the fish with A/G type at g.7409 significantly longer than that of fish with G/G type (P＜0.05). Both mean body mass and length of the fish with C/C type at g.3079 were significantly greater than those of the fish with A/A type (P＜0.05). The InDel site, g.573, reduced one serine residue in the protein encoded by EGFL9 significantly altereed the tertiary structure. Consequently, the mean body mass of the fish with TACC/T type at this site was significantly heavier than that of the fish with TACC/TACC type (P＜0.05), and the mean body length significantly longer than that of the fish with TACC/TACC or T/T type (P＜0.05).
Conclusion The 4 growth-related markers, g.142, g.573, g.3079, and g.7409, revealed by this study showed significant associations with the growth traits of I. punctatus. The information would possibly lead to the development of breeding chips and molecular marker-assisted breeding on channel catfish in the future.
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