Determination of the tolerance levels of local varieties found in the Eastern Anatolia region genetic resource plot to powdery mildew (Erysiphe necator) and downy mildew (Plasmopara viticola) diseases

This study aims to determine the resistance levels of 203 local grapevine genotypes selected from the Eastern Anatolia Region, along with two tolerant (Regent, Kishmish Vatkana) and two susceptible (Karaerik, Italia) control cultivars, against the grapevine powdery mildew (Erysiphe necator) and downy mildew (Plasmopara viticola) pathogens, and to analyze the presence of resistance genes in genotypes with different tolerance levels. In 2023, preliminary evaluations were conducted under natural infection conditions at the Erzincan Grapevine Field Gene Bank. Disease severity scores were calculated using a visual scale based on sporulation intensity and necrosis formation, and the data were analyzed using the Towsend-Heuberger formula. As a result of these evaluations, 60 genotypes showing high or moderate tolerance to natural infection were identified as prominent. In 2024, artificial inoculation studies were carried out on these selected genotypes under field, greenhouse, and laboratory conditions. Disease severity and susceptibility levels were reassessed based on similar criteria. According to the findings, 11 genotypes in field conditions, 18 in greenhouse conditions, and 11 in laboratory conditions exhibited high levels of tolerance. In addition, leaf samples were collected from the 60 genotypes selected through natural infection assessment, along with the control cultivars, and DNA isolation was performed. PCR amplifications were conducted using seven different molecular markers associated with resistance to powdery and downy mildew diseases. According to marker analysis results, the UDV-020 and VMC9h4-2 markers, associated with the Ren1 locus (powdery mildew resistance), gave positive bands in 16 and 20 genotypes, respectively, while the UDV-015 marker, associated with the Ren3 locus, gave bands in 19 genotypes. For the Rpv3 locus (downy mildew resistance), the VMC7F2 and VMCNG2F12 markers gave bands in 17 and 7 genotypes, respectively; for the Rpv4 locus, the VMCNg2e1 and VMC7h3 markers gave bands in 25 and 19 genotypes, respectively. The findings reveal that grapevine genetic resources native to the Eastern Anatolia Region have significant potential in terms of disease resistance and can be effectively utilized in future breeding programs.