Chromosome Behavior Analysis Of Meiotic Metaphase?in Newly Synthesized Tetraploid Wheat

Wheat is one of the three major grain crops,which is also a very typical allopolyploid plant.Therefore,the study of wheat is very meaningful.About 0.5 Myr ago,an occasional hybridization happened between a yet-unknown species of the genus Aegilops section Sitopsis?genome SS?BB,2n=14?and Triticum urartu?genome AA,2n=14?and formed another new allotetraploid wheat?Triticum turgidum,genome BBAA,2n=28?after some unknown stimulation.This was the first time of genome doubling and hybridization event arose in the process of wheat evolution.We have already known that the genome components of the natural tetraploid wheat is BBAA or SSAA,and the karyotype of the progeny tended to stable after a long-term evolution and selection.In order to explore the mechanism of the stabilization,we choose three genotypes of newly synthesized allotetraploid wheat:AT1(S^shS^shA^mA^m),AT3?AADD?,AT4?S^bS^bDD?,and selected the stable karyotype individual which showed nearly no change in both chromosome number and structure.Finally,we observed the chromosome behavior during the process of meiotic?metaphase.The result indicated that:like the natural tetraploid wheat,the karyotype of tetraploid wheat AT1(S^shS^shA^mA^m)was stable during the process of the meiosis?metaphase.However,the other two types AT3?AADD?,AT4?S^bS^bDD?showed the univalent,multivalent and mismatch chromosomes.We found the probability of the three abnormalities was much higher in the newly synthesized tetraploid wheat AT3?AADD?,AT4?S^bS^bDD?than in the natural tetraploid wheat and the other newly synthesized tetraploid wheat AT1(S^shS^shA^mA^m).