Origin and evolution of the bread wheat D genome.

Bread wheat (Triticum aestivum) is a globally dominant crop and major source of calories and proteins for the human diet. Compared with its wild ancestors, modern bread wheat shows lower genetic diversity, caused by polyploidisation, domestication and breeding bottlenecks1,2. Wild wheat relatives represent genetic reservoirs, and harbour diversity and beneficial alleles that have not been incorporated into bread wheat. Here we establish and analyse extensive genome resources for Tausch's goatgrass (Aegilops tauschii), the donor of the bread wheat D genome. Our analysis of 46 Ae. tauschii genomes enabled us to clone a disease resistance gene and perform haplotype analysis across a complex disease resistance locus, allowing us to discern alleles from paralogous gene copies. We also reveal the complex genetic composition and history of the bread wheat D genome, which involves contributions from genetically and geographically discrete Ae. tauschii subpopulations. Together, our results reveal the complex history of the bread wheat D genome and demonstrate the potential of wild relatives in crop improvement.

Drought-induced changes in photosynthetic apparatus and antioxidant components of wheat (Triticum durum Desf.) varieties.

Water deficit is a key factor influencing the yield and quality of crops. In the present study, the photosynthetic responses by means of chlorophyll fluorescence of chloroplasts, thylakoid membrane proteins, and antioxidant components were analyzed in wheat (Triticum durum Desf.) plants differing in their tolerance to drought. Two durum winter wheat varieties, Barakatli 95 (drought tolerant) and Garagylchyg 2 (drought sensitive) were grown under field well-watered and drought conditions. It was found that contents of the PS I core (CPI) with Mr of 123 kD and apoprotein P700 with Mr of 63 kD were relatively higher in Barakatli 95 variety under drought stress compared with the control plants. Synthesis of α- and ß-subunits of CF1 ATP-synthase complex with Mr of 55 and 53.5 kD also slightly increased in the tolerant Barakatli 95 and decreased in the drought sensitive variety Garagylchyg 2. A decrease in the intensity of 30 kD band and a significant increase were found in the content of the 25-16 kD region in Garagylchyg 2 variety. The synthesis of 60 kD and content of low molecular mass polypeptides (21.5 and 12 kD) were increased in the tolerant genotype Barakatli 95. The intensity of peaks at 687, 695, and 742 nm considerably increases in the fluorescence spectra (77 K) of chloroplasts isolated from the sensitive variety Garagylchyg 2, and there is a stimulation of the ratio of fluorescence band intensity F687/F740. At the same time, higher level of glycine betaine was found in the drought tolerant variety compared with the control one throughout the different periods of growth.