Genetical analysis of resistance to powdery mildew in triticale

Epidemic incidence of powdery mildew has become an increasing challenge in triticale growing since 2004, demonstrating the need for additional efforts in resistance breeding against powdery mildew. We report on the genetic and molecular characterization of a novel powdery-mildew resistance gene in triticale by means of a detached-leaf test using single-pustule isolates (SPIs) and molecular markers for the chromosomal localization of the resistance gene. Detached-leaf segment tests with 14 highly virulent powdery mildew SPIs were performed on 15 triticale cultivars and a JKI breeding line. The tests revealed resistance towards 13 isolates in line JKI5015. Segregation analyses of BC, F2 and F3 families of crosses between JKI5015 and two susceptible triticale strains demonstrated a monogenic dominant inheritance of the resistance. The resistance gene was preliminarily designated as Pm5015 and could be mapped to chromosome 6RL using rye-specific microsatellite markers. The identified linkage relationships between Pm5015 and EST-derived markers enables the targeted development of additional molecular markers using a comparative-genetics approach and the rice genome data as a blueprint.