Europe as a bridgehead in the worldwide invasion history of grapevine downy mildew,Plasmopara viticola

Abstract

Europe is the historical cradle of viticulture, but grapevines have been increasingly threatened by pathogens of American origin. The invasive oomycete Plasmopara viticola causes downy mildew, one of the most devastating grapevine diseases worldwide. Despite major economic consequences, its invasion history remains poorly understood. Comprehensive population genetic analyses of ~2000 samples from the most important wine-producing countries revealed very low genetic diversity in invasive downy mildew populations worldwide. All the populations originated from one of five native North American lineages, the one parasitizing wild summer grape. After an initial introduction into Europe, invasive European populations served as a secondary source of introduction into vineyards worldwide, including China, South Africa and, twice independently, Australia. Invasion of Argentina probably represents a tertiary introduction from Australia. Our findings provide a striking example of a global pathogen invasion resulting from secondary dispersal of a successful invasive population. It will help designing quarantine regulations and efficient breeding for resistance against grapevine downy mildew.

Population structure of Erysiphe necator on domesticated and wild vines in the Middle East raises questions on the origin of the grapevine powdery mildew pathogen

“…Plant pathogens with global migration patterns emerge out of their native ranges. Although these pathogens are often diverse at their centre of origin they may also exhibit genetic variation in the invaded range via multiple introductions from different source populations (Wang et al ., 2017; Fontaine et al ., 2020). Genetic bottlenecks may cause introduced plant pathogens to have low genetic diversity (Ureña‐Padilla et al ., 2002; Zhan et al ., 2003).…”

Insights into invasive species from whole‐genome resequencing

“…In summary, estimating the timing of recent and extreme changes in population size may in some cases be an intractable problem, but WGR data increases the chance of success. In simpler demographic scenarios, more affordable sequencing approaches, such as transcriptome sequencing and microsatellite markers, have shown considerable success in reconstructing invasion histories (e.g., Fontaine et al, 2021; Popovic et al, 2020). While these remain satisfactory sequencing strategies in some contexts, WGR data can increase resolution and will be especially useful in estimating the time of recent or complex invasion scenarios.…”

Taking Action - Turning Evolutionary Theory into Preventive Policies

“…Although without such protection measures, losses in crop production could increase five-fold in Europe (111), it has now become clear that global demand as well as changing climate and globalised trade have subjected crops to EIDs unmanageable by current measures. Additional to coconut yellow disease and wheat stem rust described above, tomatoes are plagued by rapidly spreading, diverse viral diseases (112), grapevine downey mildew has spread from Europe and now threatened vineyards worldwide (113), and the Fusarium incarnatum-equiseti species complex had invaded leafy vegetable crops in novel European areas (114). Although still treated as an agricultural and production issue, more studies are connecting plant diseases to the larger context of EIDs (115)(116)(117).…”