AUTHOR=Krzyzaniak Yuko , Trouvelot Sophie , Negrel Jonathan , Cluzet Stéphanie , Valls Josep , Richard Tristan , Bougaud Ambrine , Jacquens Lucile , Klinguer Agnès , Chiltz Annick , Adrian Marielle , Héloir Marie-Claire TITLE=A Plant Extract Acts Both as a Resistance Inducer and an Oomycide Against Grapevine Downy Mildew JOURNAL=Frontiers in Plant Science VOLUME=9 YEAR=2018 URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2018.01085 DOI=10.3389/fpls.2018.01085 ISSN=1664-462X ABSTRACT=

Protecting vineyards from cryptogamic diseases such as downy mildew, caused by Plasmopara viticola, generally requires a massive use of phytochemicals. However, the issues on unintentional secondary effects on environment and human health, and the occurrence of P. viticola resistant strains, are leading to the development of alternative strategies, such as the use of biocontrol products. In this paper, we evidenced the ability of a plant extract to protect grapevine from P. viticola. Further experiments carried out both on cell suspensions and on plants revealed that plant extract activates typical defense-related responses such as the production of H2O2, the up-regulation of genes encoding pathogenesis-related proteins and stilbene synthase, as well as the accumulation of resveratrol or its derivative piceid. We also brought to light a strong direct effect of PE on the release and motility of P. viticola zoospores. Furthermore, we found out that PE application left dried residues on leaf surface, impairing zoospores to reach stomata. Altogether, our results highlight the different modes of action of a new biocontrol product able to protect grapevine against downy mildew.