Effects of resveratrol, viniferins and pterostilbene on Plasmopara viticola zoospore mobility and disease development

The effects of stilbenes (resveratrol, δ- and ε-viniferins, and pterostilbene) on the mobility of zoospores of Plasmopara viticola and on subsequent disease development were studied in vitro. δ-viniferin and pterostilbene are the most toxic stilbenes concerning zoospore mobility (ED50 : 14.6 and 28.3 μM) and disease development (ED50 : 14.7 and 12.7 μM). The analysis of stilbenes in leaf cells of resistant (Solaris) and susceptible (Chasselas) grape cultivars artificially inoculated with P. viticola has shown that very high amounts of stilbenic phytoalexins accumulate at the site of infection of the resistant cultivar compared to the susceptible one.