controlled by Vf gene in Czech apple breeding

The varieties of apples resistant to apple scab (Venturia inaequalis CKE.) are among the latest outcomes of breeding this fruit species not only worldwide but also in the Czech Republic. A common donor of resistance to this disease is Malus floribunda Sieb., clone 821, which has conferred the qualitative resistance based on the dominant Vf gene to a range of varieties. The objective of this article is to characterise Vf gene in a collection of new Czech apple varieties. The published primers were used for PCR evaluation of the collection of twenty Czech varieties, seventeen varieties of world assortment and six new resistant selections of Czech breeding. All varieties possessing resistance based on Vf gene had the heterozygous constitution of Vf gene (Vfvf). Segregated F1 progeny, which was already selected by infection tests in a greenhouse, was included in the same PCR test. In all progenies recessive homozygous genotypes (vfvf) were also found that were not select-ed by the infection test. The higher occurrence of recessive homozygous genotypes (vfvf) was detected above all in the progenies of such parental combinations where one of the parents was a donor of quantitative resistance to apple scab