| Aegilops tauschii (2n = 2x = 14,DD), the donor of the D genome of hexaploid wheat (Triticum aestivum, AABBDD), has been found to possess many valuable genes what have been used to improve the quality and biotic stress resistance of bread wheat. Ae. tauschii ,which has a few of region-specific genotypes involved in the origin of hexaploid wheat, contains much wider genetic background than wheat's. There is no a large-scale investigation of Ae. tauschii in the Middle reaches of the Yellow River in China where many kinds of Ae. tauschii accessions have been found. In this work, the genetic diversity of different Ae. tauschii populations were investigated by SSR assay, and then the molecular cloning of high molecular weight glutenin subunit genes and resistance to wheat sharp eyespot were focused on the Ae. tauschii from the middle reaches of the Yellow River.(1)The genetic diversity and differentiation of 147 Aegilops tauschii accessions from Henan, Shannxi, Xinjiang in China and the Middle East, were investigated by SSR assay with 32 pairs of primers homogeneously distributed on 14 chromosomes of Ae. tauschii. The results demonstrated that 26 loci were polymorphic, with an average of 4.15 alleles on each locus. Nei's genetic diversity index (He) and polymorphism information content (PIC) value were 0.243 and 0.226, respectively. Genetic variations among different populations varied greatly. The maximal diversity values were found in Middle East population (He =0.607, PIC =0.551), which was much higher than those in Shannxi (He =0.055, PIC =0.047) and Henan (He =0.024, PIC =0.021) populations. Analysis of molecular variance (AMOVA) showed that the genetic differentiation among the geographical populations was significant (P<0.05) and accounted for about 52% of the total genetic variation. Meanwhile,the genetic differentiation was obvious between the populations of Henan and Shannxi(Fst =0.210). These results would offer useful information and evidence for further understanding the origin and evolution of the Ae. tauschii from the Middle reaches of the Yellow River, and provided genetic resources for wheat breeding.(2)To detect HMW-GS genes in Ae. tauschii resources in the Middle reaches of the Yellow River and to understand its structure and function by sequencing, 161 Ae. tauschii accessions collected in July 2006 were used in this study with Yumai 49 as a control. Through sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) technique, three y-type subunits were observed, named as Dy10.5t, Dy10.4t , and Dy10.5*t. Genes of the three subunits were amplified, cloned and sequenced by allele-specific PCR. The results revealed that the deduced amino acid sequence had typical characters of HMW-GS and a general resemblance to each other, but Dy10.4t had a repeated amino acid motif deletion to Dy10.5t, and Dy10.5*t had an amino acid substitution sites in signal peptide domain to Dy10.5t (L-F). From multiple sequence alignment and phylogenetic analysis of storage protein gene family, it is concluded that the subunits Dy10.5t,Dy10.4t and Dy10.5*t of Ae. tauschii are similar to the Glu-1 locus found in wheat and related species, and are new members of y-type HWM glutenin family. It would offer useful information and evidence for further understanding the origin and evolution of Triticum species, and it is potentially a elite gene resources for quality improvement of bread wheat.(3)The disease resistance of 128 Ae. tauschii to R. cerealis in middle reaches of yellow river of China was identified in fields by an improved method of inoculations during 2007,2008 planting seasons. The resistance to R. cerealis of varieties were different. 28 immunity, 37 high resistant, 30 middle resistant, only SX-6 is middle susceptible were identified among 96 Ae. tauschii varieties. The diversification analysis of Ae. tauschiis resistance to wheat sharp eyespot according to the relative resestance index of four phases revealed that, seventy-six varieties have a higher resistance to R. cerealis and would be used in wheat engineering in future. Investigating the resistance of Ae. tauschii in the middle reaches of yellow river to R.cerealis, will increase the genetic variability and germplasm resources for the improvement of wheat. |
