Mapping sex-determination region and screening DNA markers for genetic sex identification in largemouth bass (Micropterus salmoides)

Abstract

Largemouth bass (Micropterus salmoides) has become an important species of freshwater aquaculture in China, due to its characteristics of strong adaptability, fast growth, and good meat quality. The external morphological differences between the two sexes are not obvious, so it is impossible to accurately discriminate and identify the biological sex of largemouth bass with traditional methods. It is necessary to develop sex-specific molecular markers for research and industry purposes. In this study, 688 largemouth bass were re-sequenced, and a 260-Kb sex-linked region was identified combining genome-wide association analysis and Fst analysis. In this region, 158 sexually dimorphic SNPs and 37 sexually dimorphic insertions/deletions (InDels) were obtained. Three InDels larger than 10 bp were selected and proved to be accurate for discriminating the sex of largemouth bass. The three sex-specific markers developed and identified in this study further confirmed that largemouth bass belonged to the XX♀-XY♂ system, and provided a useful tool for elucidating the molecular mechanism of sex determination and promoting sex-controlled breeding.