Meiotic gynogenesis with heterologous sperm in the mandarin fish Siniperca chuatsi and evidence for female homogamety

The mandarin fish Siniperca chuatsi is a historically important aquaculture species in China and exhibits sexually dimorphic growth. However, sex determination of this fish remains unclear so far. In this study, we induced meiotic gynogenesis in S. chuatsi using irradiated heterologous sperm from spotted mandarin fish (Siniperca scherzeri) to uncover its mechanism of sex determination. Up to 7.52% diploid progeny were obtained among three gynogenetic families in this study. Molecular analysis of female and male donors and sampled young gynogens by seven microsatellite loci further confirmed no genetic contributions from the 'father' S. scherzeri. After 8 months of culture, external morphology of adult fish showed that all gynogens were cloned from their mothers. Gonads of the gynogenetic progeny were examined by histological observations and the sexing results showed that they were almost 100% females, strongly supporting an assumption of female homogamety in mandarin fish. By this study, we obtained pure lines of S. chuatsi and elucidated its genetic mechanism of sex determination, providing a basis for possible sex control breeding in this species.