Karyotype And Parental Preference Of Newly Synthesized Heterotetraploid Wheat In Heavy Metal Cadmium Resistance

Polyploidy plays an important role in the process from the species origin to today's colorful world,but exactly how it drives evolution has not been clearly explained.There is no denying that the environmental pressure is significant for natural selection.The development of science and technology has brought new environmental problems:heavy metal pollution.It has seriously threatened human health.Since 2007,cadmium?Cd?excessive rice caused widespread concern in the society,which led to an increasing trend of research on the mechanism of cadmium absorption and tolerance.But we only focus on model plants such as Arabidopsis thaliana and rice.Wheat is an important food crop and one of the most common polyploid plants,its formation is a historical portrayal of the polyploidy process.Nowadays,wheat become the largest planting food crops,also facing a huge risk of cadmium pollution,so its safety is particularly important.However,there are few studies on cadmium resistance of wheat.This experiment associates the cadmium resistance with the evolution of polyploid wheat:using four newly synthesis allotetraploid wheat,according to the karyotype stability divided into two groups.One group is karyotype-unstable-wheat AADD[Triticum urartu???×Aegilops tauschii???,2n=28]and S^bS^bDD[Aegilops bicornis???×Ae.tauschii???,2n=28],it was treated with cadmium and the individuals with cadmium resistance were screened with abundant karyotypes as raw materials.;the other group was S^shS^shA^mA^m[Aegilops sharonensis???×Triticum monococcum???,2n=28]and S^lS^lAA[Aegilops longissima???×T.urartu???,2n=28]with stable karyotype,treating the tetraploid and its S parents and A parents with cadmium to evaluate the parental preference of tetraploid relative to diploid parents in terms of cadmium resistance.Based on two approaches of screening and evaluation,the karyotype and parental preference of newly synthesized heterotetraploid wheat with cadmium-resistance were investigated through the analysis of cytology and physiology,to explored the evolution of polyploid wheat in specific environments,at the same time,it may bring a new idea to search for cadmium resistance genes in wheat.The main conclusions as follows:1.The number and structural variation of the resistant population are concentrated in several specific chromosomes,There was a high proportion of aneuploidy and"hidden"aneuploidy in the resistant population,and there are unprecedented new karyotypes appeared in the resistant groups;2.Under the stress of Cd,the parents of two newly synthesized tetraploid wheat A had stronger resistance compared with the parents of S,and the natural tetraploid wheat was superior and showed higher resistance compared with the newly synthesized tetraploid wheat,Cd stress resulted in the change of parental preference of the tetraploid surface type.