Development of a Wheat-Thinopyrum intermedium Robertsonian Translocation Stock With Sr44 Resistance to Stem Rust (Ug99)

Stem rust of bread wheat (Triticum aestivum L.) caused by the fungus Puccinia graminis Pers. F. is one of the most important threats of wheat production. A new stem rust race Ug99 is virulent to most of the resistant genes deployed in cultivars. New genes for Ug99 resistance can be transferred to wheat from relative species. An important step in the transfer of alien genes to wheat is the production of compensating Robertsonian translocations (RobT). These can be produced for the targeted chromosomes by the centric breakage-fusion mechanism of univalent during the meiotic division. The stem rust resistance gene Sr44, which is highly effective against Ug99 was transferred to wheat from Th. intermedium (2n=6x=42, JJJ^sJ^sSS) in the form of noncompensating translocation T7DS-7Ai#1L·7Ai#1S. The wheat- Th. intermedium RobTs were produced from a double-monosomic line for chromosomes 7D and 7J. The translocation chromosomes were analyzed by molecular markers, genomic in situ hybridization and C-banding. Rearranged chromosomes − wheat - Th. intermedium dicentrics, Th. intermedium telosomes, wheat - 7J telosomes and a RobT T7DL·7J#1S were discovered and the compensating RobT was confirmed by using chromosome bin-mapped SSR markers and chromosome 7D specific FISH markers.