Resistant Grapevine Varieties to Downy Mildew

Downy mildew (DM), caused by the oomycete Plasmopara viticola, is one of the most important diseases of grapevine worldwide. Control of DM still largely relies on fungicide applications even though the call for agricultural sustainability makes of paramount importance the exploitation of human-and eco-friendly alternatives. Partially resistant varieties, which originate from the introgression of genes of resistance to DM from wild grapevines into the Vitis vinifera genome, may contribute to a less fungicide-dependent viticulture. In these varieties, P. viticola completes its life cycle on grapevine, but one or more stages of the disease cycle are affected, leading to reduced DM severity and/or slowed the progress of the epidemics in the field. This case study describes the origins of resistance genes and their exploitation in breeding programmes, the effect of resistance on the disease cycle and DM epidemics. A focus on integrated disease management in the vineyard of DM in relation to other fungal diseases is also provided.