A direct hybridization approach to gene transfer from Aegilops tauschii Coss. to Triticum aestivum L

P>Aegilops tauschii Coss., the D-genome donor of bread wheat, represents a rich source of resistance and productivity traits for wheat improvement. In this study, a direct hybridization approach using Ae. tauschii as the female in crosses with Triticum aestivum resulted in about 50 times more F-1 plants than the reciprocal cross. In a set of five Ae. tauschii x T. aestivum crosses, an average of 35% of the pollinated florets resulted in embryo formation. Following embryo rescue on artificial medium, an average of 6.8 F-1 plants could be obtained for every 100 florets pollinated. Colchicine treatment of the F-1 plants greatly enhanced backcross seed formation (14.9 backcross seeds compared to an average of 0.47 seeds per 100 florets for untreated tillers). The efficacy of this gene transfer system was demonstrated by improved cell membrane stability and chlorophyll retention in BC1F4 lines derived from the crosses of three heat-tolerant accessions of Ae. tauschii with bread wheat cultivar 'PBW 550'.