Abnormal chromosome behavior during meiosis in the allotetraploid of Carassius auratus red var. (♀)×Megalobrama amblycephala (♂).

Qinbo Qin,Yude Wang,Shaojun Liu,Jing Dai,Juan Wang,Yun Liu

doi:10.1186/s12863-014-0095-6

Abstract

BackgroundAllopolyploids generally undergo bivalent pairing at meiosis because only homologous chromosomes pair up. On the other hand, several studies have documented abnormal chromosome behavior during mitosis and meiosis in allopolyploids plants leading to the production of gametes with complete paternal or maternal chromosomes. Polyploidy is relatively rare in animals compared with plants; thus, chromosome behavior at meiosis in the allopolyploid animals is poorly understood.ResultsTetraploid hybrids (abbreviated as 4nRB) (4n = 148, RRBB) of Carassius auratus red var. (abbreviated as RCC) (2n = 100, RR) (♀) × Megalobrama amblycephala (abbreviated as BSB) (2n = 48, BB) (♂) generated gametes of different size. To test the genetic composition of these gametes, the gynogenetic offspring and backcross progenies of 4nRB were produced, and their genetic composition were examined by chromosome analysis and FISH. Our results suggest that 4nRB can produce several types of gametes with different genetic compositions, including allotetraploid (RRBB), autotriploid (RRR), autodiploid (RR), and haploid (R) gametes.ConclusionsThis study provides direct evidence of abnormal chromosome behavior during meiosis in an allotetraploid fish.

Highlights

Allopolyploids generally undergo bivalent pairing at meiosis because only homologous chromosomes pair up
Allopolyploids result from the combination of chromosome sets from two or more different taxa that undergo bivalent pairing at meiosis because only homologous chromosomes pair up [3,4]
We provide direct evidence that abnormal chromosome behavior during meiosis occur in the allotetraploid hybrids, but bivalent pairing and the mechanisms of the abnormal chromosome behavior need to be investigated in future

Summary

Introduction

Allopolyploids generally undergo bivalent pairing at meiosis because only homologous chromosomes pair up. Allopolyploid speciation can result from chromosome doubling in a diploid hybrid to create unreduced gametes When these diploid eggs and sperm are fertilized, they produce a tetraploid [6,7]. We provide direct evidence that abnormal chromosome behavior during meiosis occur in the allotetraploid hybrids, but bivalent pairing and the mechanisms of the abnormal chromosome behavior need to be investigated in future. This is the first report of abnormal chromosome behavior during meiosis in allotetraploid fish, and will contribute to the understanding of vertebrate polyploidization and evolution

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Conclusion