'Plant Breeding: Sustaining the Future' Abstracts of the XVIth EUCARPIA Congress, Edinburgh, Scotland, 10-14 September 2001 MOLECULAR LEVEL OF RESISTANCE TO APPLE POWDERY MILDEW IN MALUS DOMESTICA BORKH KLON U 211 M. STANKIEWICZ, E. PITERA, S.W. GAWRONSKI Dept of Pomology and Basic Natural Sciences in Horticulture, Warsaw Agricultural University, SGGW ul Nowoursynowska 166, 02-787 Warsaw, Poland

The investigations concern the identification of random amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP) markers linked to the major genes for mildew resistance in field conditions.  The presence of the V1 gene conferring resistance to scab was confirmed by molecular analysis.  As the molecular markers for the P12 gene from Malus zumi are not present in the DNA of U 211 it is probable that the Klon U 211 is a new source of mildew resistance.  The RAPD and AFLP marker technique was combined with a bulked segregant analysis (BSA). Already some of polymorphisms identified between resistant and susceptible DNA pools seem to be useful for marker-assisted selection in apple breeding.