The Production Of Syhthetic Hexaploid Wheat Between Chinese Triticum Turgidum Ssp. Turgidum And Aegilops Tauschii And Its Cytology And Morphology

Under the modern agricultural system,the genetic diversity of common wheat (Triticum aestivum L.,2n=6x=42,AABBDD) has been reduced.It is necessary to broaden its genetic diversity to meet the demands for high yielding and stress-resisitant on wheat cultivars.Synthetic hexaploid wheat between between T.turgidum and Aegilops tauschii have played an important role in introgressing desirable traits from T.turgidum and Ae.tauschii into bread wheat.In this study,seven newly synthetic heaxploid wheats were produced by the spontaneous chromosome doubling of the hybrids between Chinese T.turgidum ssp.turgidum and Ae.tauschii.The cytological and morphological traits for the first generation(S₁) of these synthesized hexaploid wheats were further observed.The results were shown as following:The triple hybrids were obtained from seven cross combinations between Chinese T. turgidum ssp.turgidum and Ae.tauschii.These hybrid produced selfed seeds,with the highest seed-setting of 34.35%,and the least of 0.75%.These results indicated these hybrids were partial fertile.However,the fertility was related to their crosses.The new synthetic wheats were obtained from the selfed hybrids.Most of these S₁ plants for synthesized hexaploid wheats observed were found to have 2n=42 chromosomes,suggesting that they were amphidiploids that were spontaneously produced via a union of unreduced gametes.These synthetic hexaploid wheats and their T. turgidum ssp.turgidum donors provide new resources for the production of new amphidiploids and for the breeding of doubled haploids.For different synthetic hexaploid wheats,the average univalents were difference, varied from 0.34～3.14.The average value of univalents for Syn-SAU-23 was 0.34,which was the least among these synthetic hexaploid wheats.Meanwhile,it showed the highest bivalents of 20.84.These results suggested that Syn-SAU-23 was stable in cytology.This made it desirable for population construction for genetic analysis.These synthetic hexaploid wheats showed high plant,strong tiller ability,long spike, and low 1000-seed-weight.Plant height,tiller number,and 1000-seed-weight showed significant differences among synthetic hexaploid wheats.Furthermore,the Ae.tauschii genotypes may attribute the variation of spikelet number and 1000-seed-weight in synthetic hexaploid wheat background with same T.turgidum genotype.The T.turgidum genotypes may attribute the variation of tiller number in synthetic hexaploid wheat background with the same Ae.tauschii genotype.