Climate change impacts on grapevine leafroll disease and its transmission by mealybugs

Abstract

Climate change impacts crop plants, plant pathogens, and their insect vectors and hence adds abiotic stress to the triangle of plant-virus-vector interactions. Grapevine is among the most widely grown fruit crops worldwide and grapevine leafroll disease (GLRD) is probably the most widespread viral infection in vineyards. It is transmitted through infected propagation material and insect vectors, such as the vine mealybug Planococcus ficus (Signoret). Knowledge of climate change impacts on mealybugs in general or as virus vectors, in particular, is scarce. Similarly, we lack information on grapevine plant defence against pathogens under climate change conditions. Plant-virus-vector interactions are usually very species-specific hence conclusions cannot be derived from other pathosystems. It is therefore unclear how climate change influences the plant-virus-vector interactions of GLRD. We exposed potted grapevines to elevated temperature (eT) and elevated CO2 (eCO2) and inoculated them with mealybugs carrying GLRD viruses. After 4 months transmission rates, defence-related plant metabolites, and gene expression patterns were analysed. Our results show higher virus transmission under ambient climate scenarios, while defence parameters were influenced by climate rather than virus infections. These findings will close knowledge gaps on plant-virus-vector interactions, and the disease they cause in current and future climate scenarios. Enhancing the knowledge of the impacts of climate change on economically important plant diseases and their insect vectors is crucial to strengthen the adaptive capacity of crop production and ensure sustainable viticulture.