RAPD and microsatellite analysis of diploid gynogens from allotetraploid hybrids of red crucian carp (Carassius auratus)×common carp (Cyprinus carpio)

Genetic variation was comparatively analyzed between the artificially induced diploid gynogen population from F₁₀ allotetraploid hybrids of red crucian carp (♀) (Carassius auratus red var., 2n=100)×common carp (♂) (Cyprinus carpio L., 2n=100) and the normal F₁₀ allotetraploid hybrid population used as the control, using random amplified polymorphic DNA (RAPD) assay and microsatellite analysis. The specific 600-bp fragment for diploid gynogen population was detected by S45 and the specific 900-bp fragment for allotetraploid F₁₀ hybrid population was detected by S134. The results from RAPD assay and microsatellite analysis were in agreement with each other, that is to say, the diploid gynogens presented lower level of polymorphism than allotetraploid F₁₀ hybrids. Furthermore, as expected, microsatellite analysis revealed more detailed information on genetic diversity than RAPD assay. The mean percentage of polymorphic loci (12.71%) and Shannon's index of phenotypic diversity (0.25) from RAPD data for diploid gynogen population were significantly lower than those (30.69% and 0.63, respectively) for F₁₀ allotetraploid hybrid population. The mean number of alleles per microsatellite locus (1.73) in diploid gynogen population was considerably lower than that (2.55) in F₁₀ allotetraploid hybrid population. The average observed (0.36) and expected heterozygosity (0.26) in diploid gynogen population were lower than those (0.58 and 0.40, respectively) in F₁₀ allotetraploid hybrid population, indicating that the diploid gynogens presented lower genetic diversity than the allotetraploids. In addition, the mean effective number of alleles at 11 microsatellite loci (1.60) in diploid gynogen population was lower than that (1.88) in F₁₀ allotetraploid hybrid population. The significant differences between two populations in the average observed and expected heterozygosity, mean number of alleles and effective number of alleles, suggested that the effect of gynogenesis resulted in rather higher genetic homogeneity in diploid gynogens. The comparative RAPD analysis of diploid gynogens and their parents was performed with 34 primers. The identical RAPD pattern was detected between diploid gynogens and their female parent, however, some clear specific RAPD bands were detected between diploid gynogens and their male parents, but not detected in their female parent. The result indicated that heterologous genetic material had incorporated into diploid gynogenetic fish (G₁).