Evaluation of the resistance mechanisms of new fungus-resistant grape varieties

Winegrowing worldwide relies on European grape varieties. However, these are highly susceptible to American pathogens—powdery mildew and downy mildew—that were introduced in the 19th century. This problem requires the massive use of fungicides or copper-based preparations to reduce the enormous crop yield losses.
One way to reduce the use of fungicides is to increase the cultivation of fungus-resistant grape varieties (“Piwis”). To this end, resistance traits against powdery mildew and downy mildew from American or Asian wild grapevines have been introduced into susceptible European grape varieties through long-term crossbreeding programs. Cultivating these new varieties can improve the future of viticulture in terms of factors such as sustainability, resource use, and environmental protection.

In this project, new fungus-resistant grapevine varieties are being studied for their resistance to powdery mildew and downy mildew. Various plant protection strategies for Piwis with different levels of resistance are being tested, and the severity and frequency of powdery mildew and downy mildew infestations are being determined over a three-year period. Based on the results, recommendations for action will be provided to contribute to sustainability in plant protection for Piwis, sensibly reduce the use of fungicides in viticulture, and thereby support the cultivation of these varieties.

Furthermore, the resistance mechanisms of selected fungus-resistant grapevine varieties against downy mildew are being investigated. Insights into the various defense mechanisms and the resistance loci involved are intended to contribute to a better understanding of the molecular basis and, building on this, to evaluate the stability and durability of the defense mechanisms against aggressive isolates of downy mildew, in order to ensure sustainability in resistance management and breeding.