| description |
The European grapevine, Vitis vinifera, cultivated worldwide for wine production, is extremely susceptible to the agent of downy mildew, Plasmopara viticola, due to the absence of co-evolution with the pathogen, originated in Northern America. The disease management is based on the frequent application of fungicides, that have a strong impact on human health and environment. Nowadays, breeding for resistance is based on the hybridization with non-vinifera resistant species through a complex backcrossing procedure aiming to eliminate unpleasant characteristics of the american grapes. A recent study showed that Mgaloblishvili, a winemaking V. vinifera cultivar from Georgia (South Caucasus), exhibited a promising resistant phenotype against P. viticola. To explore its resistance mechanisms, we investigated pathogen development and plant response by experimental inoculations, confocal microscopy and transcriptomics analyses on Mgaloblishvili, Pinot noir (a winemaking susceptible variety) and Bianca (a non-vinifera resistant cultivar). The comparative analysis highlighted that defense responses in Mgaloblishvili, leading to a limitation of P. viticola growth and sporulation, are determined by the overexpression of genes that are downregulated in Pinot noir and have unique features compared to Bianca, where the hypersensitive response was observed. Those genes are involved in pathogen recognition, ethylene signalling pathway, synthesis of antimicrobial compounds and enzymes, and in the apposition of structural barriers. The unique resistant traits found in Mgaloblishvili highlighted the presence of a defense system in V. vinifera against P. viticola that could be exploited in new breeding programs. |