AN EFFECTIVE METHOD FOR CREATING ALLO-OCTOPLOIDS BY INTEGRATING EXOGENOUS SPERM GENOME INTO GIBEL CARP EGGS

Gibel carp (Carassius auratus gibelio Bloth) possesses a special ability to integrate exogenous sperm genome or chromosome fragments into its eggs for co-development, but the spontaneous formation probability is very low in allogynogenetic offspring. In this study, white crucian carp (C. cuvieri) sperm were treated by 0.25%, 0.5%, 1%, 2% and 4% trypsin solution for 10min, or by 1% trypsin solution for 5, 10, 15, 20 and 25min respectively, and then fertilized with mature eggs of allogynogenetic gibel carp clone A⁺. By comparing the changes of sperm structure and motility between control group and different treatment groups, also considering reproductive indexes, such as fertilization rate, hatching rate and survival rate, as well as occurrence rate of allo-octoploids, an effective method was established to integrate exogenous sperm genome into allogynogenetic gibel carp eggs to create allo-octoploids. The average survival rate and octoploid rate were (2.4±0.7)% and (16.3±0.5)% respectively when the eggs of gibel carp clone A⁺ were fertilized with white crucian carp sperm treated by 1% trypsin solution for 15min. The effective method developed in this study will be a valuable way for creating novel genetic resources with excellent economic traits in gibel carp genetic breeding. Subsequently, 57 allo-octoploid adults were obtained by batch processing and flow cytometry screening from 6-month-old offspring, which can be used as core population for breeding of novel gible carp varieties with faster growth and or higher disease-resistance.