Gynogenetic Cirrhinus mrigala produced using irradiated sperm of Cyprinus carpio exhibit better cold tolerance

Artificial gynogenesis is an important method for accelerating the selective breeding of varieties and populations. In this study, ultraviolet-irradiated sperm of Common carp (Cyprinus carpio) was used to activate the mature eggs of mrigal carp (Cirrhinus mrigala, MC), after cold shock at 4–8 °C for 16 min to double the chromosomes, a population of gynogenetic mrigal carp (GMC) was obtained. The fertilization rate, hatching rate and survival rate of GMC exceeded 62.2%, 6.3% and 2.9%, respectively. Comparative analyses of morphological traits, DNA content, chromosome numbers and 5S rDNA sequences showed no significant differences between MC and GMC. However, microsatellite (MFW1, CCA15) analysis revealed that paternal DNA fragments were inserted and a parent DNA fragment was deleted in the GMC. The GMC population survived the natural winter for more than 50 days with a temperature below 10 °C, while all the normal MC individuals perished. In addition, lower critical thermal minimum (CTMin) and lethal temperature (T_LD50) values were detected in GMC than that in MC. Our results indicated that the artificial gynogenesis method improved the cold tolerance of mrigal carp. The results of this study are of great significance for fish breeding and application.