Manipulation of Chromosomal Segments From Wild Wheat for the Improvement of Bread Wheat

Abstract

Specific alien chromatin segments have been used for many years to introduce novel disease resistance genes into bread wheat. The 1RS chromosome segment being used in Australian wheats will be discussed in detail to present the molecular biological studies carried out on this chromosome segment as well as its agronomic contributions to wheat. Studies are also being carried out on the manipulation of the D genome of wheat. Within Australia we have initiated the screening of a collection of 420 accessions of Triticum tauschii (the donor of the D genome) involving groups in the Departments of Agriculture in New South Wales, Victoria, Western Australia and the University of Sydney as well in the Division of Plant Industry. Disease resistance has been sought and found for cereal cyst nematode, Septoria nodorum, Septoria tritici, Puccinia striiformis, P. recondita and P. graminis. At the DNA level the collection has been screened for variation at the 5Sdna and Nor loci, as well as generating Pst (a restriction endonuclease) genomic clones, in preparation for providing RFLP markers for a genetic linkage map. Lines of T. tauschii showing high levels of disease resistance have been crossed directly to Australian wheat cultivars or are being used to form synthetic hexaploids by crossing to tetraploid wheats.