Formation and identification of artificial gynogenetic mandarin fish (Siniperca chuatsi) induced by inactivated sperm of largemouth bass (Micropterus salmoides)

Gynogenesis is a special method of distant hybridization that has important application value in a variety of areas, such as rapid establishment of pure lines, restoration of endangered species and sexual control. Mandarin fish is an important aquaculture species in China that exhibits sexually dimorphic growth. However, there are few studies on the gynogenesis of mandarin fish at present, and there is no report on gynogenesis induced by cross-family heterologous sperm. In this study, we used the sperm of largemouth bass (Micropterus salmoides, LB, Family Centrarchidae, 2n = 46) with UV-inactivated genetic material to stimulate gynogenesis in mandarin fish (Siniperca chuatsi, MD, Family Serranidae, 2n = 48) to obtain surviving offspring. To determine whether the offspring obtained by the gynogenetic technique are gynogenetic fish, we analyzed the DNA content, chromosome number, karyotype, countable traits, 5S rDNA and mitochondrial DNA of the offspring. Based on the analysis of the above experimental results, it was found that the offspring was a diploid fish with 48 chromosomes, its karyotype was 6sm + 12st + 30 t, and the 5S rDNA gene included two fragments with sizes of 203 bp and 281 bp. These characteristics were consistent with MD. The DNA content, countable traits, and mitochondrial DNA sequence of the offspring were not significantly different from MD. Afterward, we identified the sex of the gynogenetic mandarin fish (GMD) through sex-specific markers. The results showed that all the mandarin fish obtained in this study are female. The microsatellite pattern showed that GMD contained bands from the male parent. In general, this is the first time that carnivore mandarin fish have obtained full female gynogenesis through gynogenesis. Additionally, this study provides a theoretical reference for the gynogenesis of fish in different subfamilies, and the acquisition of all-female mandarin fish has certain commercial value for production practices.