Molecular detection of powdery mildew resistance in indigenous and exotic Vitis genotypes

The obligate biotrophic ascomycete fungus Erysiphe necator belongs to the family Erysiphaceae (Leotiomycetes; Erysiphales) causes powdery mildew (PM), a most destructive and widespread fungal disease in grapevine. Exploring the potential genetic resistance in grape genotypes and the introgression of this efficient genetic resistance into cultivated grapevines could be a sustainable alternative for managing powdery mildew disease. Marker-assisted selection by using 21 known SSR markers associated with different PM-resistant loci combined with controlled (artificial) inoculations was utilized in this study to screen the wide range of Vitis germplasm to identify resistance to powdery mildew. The genotype with strong resistance to PM was further used to determine response alterations in biochemical parameters compared to the susceptible genotype. Amongst 40 Vitis genotypes, Male Hybrid, Pusa Navrang, Pearl-of-Csaba, Pusa Swarnika, Dog Ridge, Salt Creek, 110 Richter, St. George, 1103 Paulsen, Couderc 1613, V. parviflora and V. jacquemontii were identified as resistant sources. Two SSR markers, VMC1A5 and VMC3d12 were the most informative about identifying genotypes with effective powdery mildew disease resistance. The total phenolic content increased significantly in both the resistant and susceptible genotypes compared to non-inoculated vine leaves (6.29 and 9.53%). After artificial inoculation, the leaves in the susceptible genotype showed 31.36% higher malondialdehyde accumulation compared to the resistant genotype. The artificial inoculated leaves of the resistant genotype, V. parviflora had 58.96% enhancement in phenylalanine ammonia-lyase (PAL) antioxidant activity compared to non-inoculated leaves (23.70%) in the susceptible genotype.