RATIO OF HOMOZYGOUS AND HETEROZYGOUS VF GENOTYPES IN THE PROGENIES OF APPLE VFVF X VFVF CROSSES

The apple-breeding program initiated at the Department of Pomology at the Corvinus University of Budapest in the 1990s is aimed on high quality cultivars with multiple disease resistance. In order to select appropriate parent cultivars and to characterize durability of scab resistance, it is important to clarify the mechanism of inheritance of scab resistance. The aim of this study was to demonstrate the occurrence of genotypes homozygous for the Vf resistant gene in progenies derived from Vf resistant heterozygous genotypes, the Hungarian candidate variety (MR-09). MR-09 was crossed in 2006 with Vf resistant cultivars ‘Remo’ and ‘Florina’. AL-07-SCAR marker for the scab resistance gene Vf have been applied to 59 progenies of two Vf x Vf crosses. The results indicate that the AL-07-SCAR marker can be used as a useful and reliable tool to predict the Vf genotype of the seedlings derived from the new Hungarian candidate cultivar (MR-09). Since each parent was heterozygous for the Vf gene, the expected ratio was 1:2:1 (VfVf : Vfvf : vfvf) as predicted by Mendelian segregetion. Population of MR-09 x ‘Remo’ segregated with the ratio of 1:1.5:2, while the observed ratio in progeny of MR-09 x ‘Florina’ was 1.5:1.5:1.