Transfer of rye chromosomes carrying Karnal bunt resistance to Triticum aestivum cv. WL711

The disomic addition lines of chromosomes 4R and 6R of Secale cereale cv. Imperial rye in Triticum aestivum cv. Chinese Spring were completely free from Karnal bunt disease of wheat under artificial inoculation. The rye chromosomes 4R and 6R were transferred into a high yielding but Karnal bunt susceptible bread wheat variety WL711 through backcrossing. The monosomic and disomic addition lines of 4R and 6R in WL711 also maintained resistance against a particular isolate of Karnal bunt during backcrossing whereas their euploid segregants were as susceptible as the recurrent parent. The 4R and 6R addition lines, however, were susceptible to a new isolate of Neovossia indica virulent on triticale. The work to substitute the rye chromosomes for their B and D wheat genome homoeologues is in progress