Rapid changes in P. infestans populations causing late blight in Europe, America and Asia, including the emergence of strains with increased aggressiveness or reduced fungicide sensitivity, have been observed. Indeed, the changes in P. infestans populations directly influence the development and deployment of resistant cultivars, the performance of disease warning systems and the efficacy of plant protection products.
Example of a late blight case included in the Euroblight database
Over the last five years, 60-79% of the population comprised known clonal lineages that recur each season. The remaining samples were novel, genetically diverse genotypes mostly found at a single location in one season and grouped in a category termed ‘Other’ (below).
Mapping of the Phytophthora infestans genotypes found accross Europe in the EuroBlight
sampling during 2017. Click image to access an interactive version of this map.
(Courtesy: Euroblight 2018)
The genetic diversity of the 2017 population can be visualised using an analysis tool (poppr 2.0) linked to the EuroBlight pathogen database. The minimum spanning network (below) shows the 2017 population structure, only including identified clones. Considerable sub-clonal diversity within the 13 year old EU_13_A2 lineage is observed compared to that in the ‘younger’ clones. ‘Other’ isolates (not shown) are genetically diverse and distributed across the whole network. Detailed analysis is underway to examine population change using these tools.