Molecular assessment of apple varietal diversity in Uzbekistan for genetic resistance to major pathogens

Background Apple ( Malus domestica Borkh .) is one of the most economically important fruit crops, but serious diseases, including fire blight ( Erwinia amylovora ), powdery mildew ( Podosphaera leucotricha ), and apple scab ( Venturia inaequalis ), threaten its output. A sustainable substitute for chemical control is the breeding of resistant cultivars, particularly for local germplasms in Central Asia. This study aimed to evaluate the presence and distribution of resistance genes in local apple varieties from Uzbekistan via polymorphic DNA markers. Results Molecular analysis revealed high genetic diversity in resistance gene combinations among accessions. For fire blight resistance, the marker AE10-375 was detected in 81% of the samples, whereas 76.6% of the accessions carried both the Pl1 and Pl2 genes conferring resistance to powdery mildew. For apple scab, the resistance genes Vfa2, Vfa1, and Vf were the most common, with Vfa2 present in 95.4% of the samples. Regionally, the Karakalpakstan accessions presented the highest proportion of multidisease resistance. Six varieties — Atlas olma, Turkish, Xuboni, Krasniy jeleznyak, Shoyi olma, and Besh barmoq — combined resistance markers for all three diseases. Conclusions Local apple varieties from Uzbekistan represent valuable sources of multidisease resistance. The identified resistant genotypes can serve as donors in breeding programs aimed at developing cultivars with durable resistance, reducing the dependence on fungicides and antibiotics in orchard management.