Cytological and genetic analyses of a wheat-rye 2RL ditelosomic addition line with adult plant resistance to powdery mildew

Rye(Secale cereale genome RR),a close relative of common wheat,possesses valuable resistance genes for wheat improvement.Due to the co-evolution of pathogen virulence and host resistance,some resistance genes derived from rye have lost effectiveness.Development and identification of new,effective resistance genes from rye is thus required.In the current study,wheat-rye line WR56 was produced through distant hybridization,embryo rescue culture,chromosome doubling and backcrossing.WR56 was then proved to be a wheat-rye 2 RL ditelosomic addition line using GISH(genomic in situ hybridization),mc-FISH(multicolor fluorescence in situ hybridization),ND-FISH(non-denaturing FISH),mc-GISH(multicolor GISH)and rye chromosome arm-specific marker analysis.WR56 exhibited a high level of adult plant resistance to powdery mildew caused by Blumeria graminis f.sp.tritici(Bgt).This resistance was carried by the added 2 RL telosomes and presumed to be different from Pm7 which is also located on chromosome arm 2 RL but confers resistance at the seedling and adult stages.WR56 will be a promising bridging parent for transfer of the resistance to a more stable wheat breeding line.A newly developed2 RL-specific KASP(kompetitive allele specific PCR)marker should expedite that work.