A new type of triploid fish derived from female Carassius auratus red var. × male Gobiocypris rarus

Abstract

Distant hybridization can combine the genomes of the parental species, leading to changes in both genotypes and phenotypes in the hybrids, often accompanied by the appearance of polyploid progeny. In this study, we obtained an allotriploid hybrid (RR, 3n = 125) through inter-subfamily hybridization between female red crucian carp (Carassius auratus red var., RCC, 2n = 100) and male rare gudgeon (Gobiocypris rarus, RG, 2n = 50). We investigated the fertilization rate, hatching rate, morphological traits, chromosome number, DNA content, 5S rDNA, mitochondrial DNA (mtDNA), growth rate and muscle fibers in RR. The results indicated that RR is an allotriploid fish with 125 chromosomes. RR exhibited a fertilization rate of 70.30 %, a hatching rate of 52.70 %, and displayed morphological traits that were intermediate between those of its parents. The 5S rDNA of RR inherited specific bands from both parents, with recombination and mutation. Through sequence alignment and the NJ evolutionary tree analysis, the mtDNA of RR showed a higher similarity to that of RCC, with some partial base insertions observed, indicating that the mitochondria of RR follows maternal inheritance. At 12 months of age, the mean weight of RR was significantly increased by 18.43 % compared to RCC. Furthermore, the total area and mean area of muscle fiber of RR increased significantly than those of RCC, indicating muscle hypertrophy and hyperplasia. This study provided a new approach to create allotriploid fish.