In this study, we report the complete
mitochondrial DNA (
mtDNA) sequences of the allotetraploid and
triploid crucian carp and compare the complete
mtDNA sequences between the
triploid crucian carp and its female parent Japanese crucian carp and between the
triploid crucian carp and its male parent allotetraploid. Our results indicate that the complete
mtDNA nucleotide identity (98%) between the
triploid crucian carp and its male parent allotetraploid was higher than that (93%) between the
triploid crucian carp and its female parent Japanese crucian carp. Moreover, the presence of a pattern of identity and difference at synonymous sites of mitochondrial genomes between the
triploid crucian carp and its parents provides direct evidence that
triploid crucian carp possessed the recombination
mtDNA fragment (12,759 bp) derived from the paternal fish. These results suggest that
mtDNA recombination was derived from the fusion of the maternal and paternal mtDNAs. Compared with the haploid egg with one set of genome from the Japanese crucian carp, the diploid sperm with two sets of genomes from the allotetraploid could more easily make its
mtDNA fuse with the
mtDNA of the haploid egg. In addition, the triple hybrid nature of the
triploid crucian carp probably allowed its better
mtDNA recombination. In summary, our results provide the first evidence of
mtDNA combination in
polyploid fish.