Production of all-triploid derived from gynogenetic homologous diploid crucian carp (♀) × diploid red crucian carp (♂)

Abstract

Triploid breeding is vital in aquaculture production. Here, based on the formation of all-female gynogenetic homologous diploid crucian carp (G, 2 n = 100) derived from gynogenesis of the autotetraploid crucian carp (4nRR, 4 n = 200) eggs and without chromosome duplication treatment, a novel triploid fish (3nRR, 3 n = 150) were produced by crossing G and males of red crucian carp (RCC, 2 n = 100). All 3nRR possessed 150 chromosomes and were triploid hybrids. The genetic characteristics of 5S rDNA in 3nRR individuals and their parental counterparts, as well as the measurable and countable traits, were explored. The 3nRR males exhibited improper sperm development, whereas 3nRR females produced mature eggs by two years old. Females of 3nRR produced various-sized eggs that fertilized with haploid sperm from RCC, producing viable diploids, triploids and tetraploids. Analysis of gonadal transcriptome between 3nRR and RCC revealed that BMP2 was linked to fertility of female 3nRR, and SOX2 plays a significant role in the male sterility of 3nRR. The findings of this study suggested that the stable production of triploid fish could be achieved via the hybridization of diploid fish. The triploids have important application values in protecting germplasm resources and preparing polyploid fish.