Production of diploid gynogenetic grass carp and triploid hybrids derived from the distant hybridization of female grass carp and male topmouth culter

Distant hybridization is an effective tool to create offspring with different ploidy levels and is widely used in plants and lower organisms. In this study, the diploid gynogenetic grass carp (2nGGC, 2n = 48) and triploid hybrid (3nGT, 3n = 72) progenies of female grass carp (Ctenopharyngodon idellus, GC, Leuciscinae, 2n = 48) × male topmouth culter (Erythroculter ilishaeformis, TC, Cultrinae, 2n = 48) were successfully obtained by distant hybridization. The results regarding the chromosomal number, DNA content, 5S rDNA and fluorescence in situ hybridization (FISH) showed 2nGGC was derived from gynogenesis with 48 chromosomes and not a hybrid of GC and TC, while 3nGT was a triploid hybrid with 72 chromosomes. 3nGT exhibited significant phenotypic differences from GC and TC, but 2nGGC resembled GC. With regard to feeding, both 2nGGC and 3nGT were herbivorous. However, the total amino acid contents in the muscles of both 2nGGC and 3nGT were significantly higher than that in GC (P