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Apple is one of the most consumed fruits in the world and as well one of the most important crops in temperate areas. Apple scab, caused by Venturia inaequalis is damaging diseases that affects apple species and causes up to 70% yield losses depending of cultivar’s resistance. In order to control this disease, costly chemical pesticides are necessary, which increase the pollution of environment by their toxicity. This study is focused on checking the behaviour of certain apple varieties from the pomological collection at UASVM Cluj-Napoca against apple scab infection. Nine apple cultivars ('Fuji Kiku', 'Red Cap', 'Lena', 'Katja', 'Gala Mitchgla', 'Fiesta', 'Yellow', 'Pinova' and 'Reinette du Canada'), were analysed in terms of behaviour to scab attack on leaves and fruits. Visual observations were completed by molecular analyses for the potential presence of the Vf gene in some cases. Combining results from visual observation and molecular assays, the 'Lena' and 'Pinova' cultivars were noted as resistant to scab in our field trial conditions. This indicates a good opportunity to bring them into apple breeding programs for resistance to apple scab.

Scab resistance through the Rvi6 gene was largely used in Romanian breeding programs including those from Fruit Research & Development Station (FRDS) Bistrita. The aim of the study was to verify the efficacy of the resistance due to the Vf gene under the current conditions in the Bistrita area. Three scab resistant apple cultivars bred at FRDS Bistrita were monitored in the field, in comparison with the Rvi6 ‘Florina’ and ‘Prima’ cvs., and the sensitive ‘Idared’ and ‘Golden Delicious’ cvs. Molecular markers (AM-19, U1₄₀₀ and AL07) were used in PCR to check the presence of the Rvi6 gene in the genome of the three Romanian varieties. During the years 2019-2021, scab lesions appeared on all the resistant cultivars studied. PCR results showed the presence of Rvi6 gene on ‘Bistritean’, ‘Salva’, ‘Aura’, ‘Prima’ and ‘Florina’ genoms. The results suggest a possible breakdown of the resistance given by the Rvi6 gene in the current ecological conditions in this area. Scab symptoms occurring on cultivars that have the Rvi6 gene could lead to the hypothesis that different scab races are now present in our area or that some genetic variations occurred on the existing races so that they overcome Rvi6 gene.

Bacterial diseases induce various symptoms on all fruit tree species cultivated in Bistrita area, north Transylvania, Romania. The preliminary results showed a very high incidence of bacterial associated symptoms in this sour cherry plot, only 1.14% of the trees was without any symptoms, and suggest a rapid evolution of the attack on leafs and young branches. In the future we will continue this study with laboratory tests in an attempt to determine the etiological agent causing the bacterial diseases in this orchard.

Apple scab, caused by Venturia inaequalis, is one of the most damaging pathogens affecting apple species. Cross combinations were made between the Salva cv. (female parent), a valuable local cultivar known for its fruit quality and used as a donor of the Vf resistance gene, and Jonathan (male parent), a variety widely cultivated but susceptible to scab. The Vf gene was first identified in Malus floribunda Clone 821, which was subsequently transferred to commercial varieties through various breeding programs. To confirm the presence of the Vf gene, the progeny from this cross was tested using Marker-Assisted Selection (MAS) with one dominant primer pair (AM19) and two codominant primers (AL07 and VFC) to distinguish between homozygous and heterozygous genotypes. From the crossing, 67 hybrids were obtained, of which 35.8% (24 hybrids) were classified as resistant (heterozygous - Vfvf), while 64.2% (43 hybrids) were classified as susceptible (recessive homozygotes - vfvf). This population of hybrids resistance to Venturia inaequalis represents a good starting point in obtaining cultivars with resistance to scab.