Research on the allogynogenetic biological effects in the second generation gynogenetic of Carassius auratus var. pengsenensis induced with sperms from Elopichthys bambusa and Culter alburnus

The technology of allogynogenesis has great application potential in the breeding of superior varieties. Carassius auratus var. pengsenensis is a kind of hermaphroditic triploid crucian carp with natural gynogenetic reproduction and it is one of the best freshwater breeding varieties in China. The development of gynogenesis of C. auratus var. pengsenensis induced with heterologous sperms can produce normal surviving progeny. The study on allogynogenetic biological effects in progeny can provide reference for the cultivation of excellent new varieties of C. auratus var. pengsenensis. In this study, the eggs of C. auratus var. pengsenensis were fertilized with sperms from Elopichthys bambusa and Culter alburnus for two successive generations, respectively. We succeeded in obtaining their second generation offsprings, P×G (C. auratus var. pengsenensis ♀ × E. bambusa ♂) and P×Q (C. auratus var. pengsenensis ♀ × C. alburnus ♂). The chromosomal karyotype, DNA content, morphological traits, and growth performance of offsprings were compared with P×P (C. auratus var. pengsenensis). The findings suggest that the karyotype formulas of P×G, P×Q and P×P was 3n=150=45m+66sm+27st+12t, 3n=150=54m+51sm+39st+6t and 3n=150=51m+48 sm+45st+6t, respectively. It is significantly different from the karyotype of E. bambusa (2n=48=10m+24sm+12st+2t) and of C. alburnus (2n=48=16m+26sm+6st). Furthermore, observed ratio of nuclear DNA content of P×G and P×Q to nuclear DNA content of P×P was within the 95% confidence interval (both 0.97), showing that P×G and P×Q produced by heterologous sperms were gynogenetic triploid fishes. The findings of principal component analysis based on morphological parameters reveal almost no overlap between the scatter plots of P×Q and P×G and P×P; there seem to be significant morphological differences between P×Q and P×G and P×P (P<0.05) that can be made preliminary discrimination by discriminant function (the accuracy rate reached 97.8%). These findings suggest that there is a significant allogynogenetic biological effects between P×Q and P×G progeny. As compared to P×P, P×G and P×Q demonstrated benefits in terms of mean body weight, mean body length, body weight growth rate and body length growth rate at each age, and P×G had significant benefits (P<0.05). In conclusion, sperms from both E. bambusa and C. alburnus can promote gynogenic development of C. auratus var. pengsenensis eggs, and different sperm sources have varied effects on the development of gynogenic nucleus and progeny, as expected from allogynogenetic biological effects. Through the research results, we can preliminarily judge the better sperm stimulation source, which lays the foundation for the subsequent breeding of C. auratus var. pengsenensis excellent new varieties.