The variability of Venturia inaequalis CKE. Races in the Czech Republic and the accumulation of resistance genes in apple germplasm

Abstract

The growing of resistant apple varieties against the scab, impacts the Venturia inaequalis CKE. races development that can overcome the resistance. For this reason the main breeders object is to cumulate the different genetic mechanisms of resistance against this disease. Presented in this paper is the first genetic study of monosporic isolates in the Czech Republic. By means of RAPD and UPGMA methods which characterised the variability of 10 monosporic isolates from different localities and apple varieties. The monosporic isolate derived from the resistant genotype (Vf gene) proved a 79% genetic similarity with the isolate derived from sensitive variety Top Red. The genetic similarity of other isolates did not prove the dependence either on a locality or a host variety. The Vf and Vm genes accumulation in apple germplasm by means of specific PCR markers was studied. It was confirmed that Vf gene donors are always heterozygous. Concurrently it was statistically confirmed that the donor of Vm gene (OR-45-T-132) is heterozygous, too. The accumulation of Vf and Vm major genes against the scab was validated in 25% of seedlings of the cross.