This study provides genetic evidences at the chromosome,
DNA content,
DNA fragment and sequence, and morphological levels to support the successful establishment of the
polyploid hybrids of red crucian carp x blunt snout bream, which belonged to a different subfamily of fish (Cyprininae subfamily and Cultrinae subfamily) in the catalog. We successfully obtained the sterile
triploid hybrids and bisexual fertile
tetraploid hybrids of red crucian carp (RCC) (female symbol) x blunt snout bream (BSB) (male symbol) as well as their pentaploid hybrids. The
triploid hybrids possessed 124 chromosomes with two sets from RCC and one set from BSB; the
tetraploid hybrids had 148 chromosomes with two sets from RCC and two sets from BSB. The females of
tetraploid hybrids produced unreduced
tetraploid eggs that were fertilized with the haploid sperm of BSB to generate pentaploid hybrids with 172 chromosomes with three sets from BSB and two sets from RCC. The ploidy levels of
triploid,
tetraploid, and pentaploid hybrids were confirmed by counting chromosomal number, forming chromosomal karyotype, and measuring
DNA content and erythrocyte nuclear volume. The similar and different
DNA fragments were PCR amplified and sequenced in
triploid,
tetraploid hybrids, and their parents, indicating their molecular genetic relationship and
genetic markers. In addition, this study also presents results about the phenotypes and feeding habits of
polyploid hybrids and discusses the formation mechanism of the
polyploid hybrids. It is the first report on the formation of the
triploid,
tetraploid, and pentaploid hybrids by crossing parents with a different chromosome number in vertebrates. The formation of the
polyploid hybrids is potentially interesting in both evolution and fish genetic breeding.