Use of Alien Genes for the Development of Disease Resistance in Wheat

The genus Triticum contains three ploidy levels and about 30 species. Most of these species have been investigated as sources of disease-resistance genes and several have been used in successful transfers of resistance to domestic wheat (T. aestivum. genomes AABBDD). In addition, at least six genera from the tribe Triticeae have been used successfully as donors of disease-resistance genes for domestic wheat. The amount of alien chromatin involved in these transfers varies from a single gene to chromosome arms or entire chromo­ somes. No attempt was made in this review to describe all alien resistance gene transfers in wheat or to outline the various techniques involved. Alien disease resistance genes covered in detail are those that confer resistance to barley yellow dwarf virus, wheat streak mosaic virus, Cephalosporium stripe (caused by Cephalosporium gramineum) and eyespot (caused by Pseudo­ cerosporella helpotrichoides).