Data from: The genetic structure of the plant pathogenic fungus Melampsora larici-populina on its wild host is extensively impacted by host domestication

Wild and cultivated plants represent very different habitats for
pathogens, especially when cultivated plants bear qualitative resistance
genes. Here, we investigated to what extent the population genetic
structure of a plant pathogenic fungus collected on its wild host can be
impacted by the deployment of resistant cultivars. We studied one of the
main poplar diseases, poplar rust, caused by the fungus Melampsora
larici-populina. A thousand fifty individuals sampled from several
locations in France were phenotyped for their virulence profile (ability
to infect or not the most deployed resistant cultivar ‘Beaupré’), and a
subset of these was genotyped using 25 microsatellite markers. Bayesian
assignment tests on genetic data clustered the 476 genotyped individuals
into three genetic groups. Group 1 gathered most virulent individuals and
displayed evidence for selection and drastic demographic changes resulting
from breakdown of the poplar cultivar ‘Beaupré’. Group 2 comprised
individuals corresponding to ancestral populations of M. larici-populina
naturally occurring in the native range. Group 3 displayed the hallmarks
of strict asexual reproduction, which has never previously been
demonstrated in this species. We discuss how poplar cultivation has
influenced the spatial and genetic structure of this plant pathogenic
fungus, and has led to the spread of virulence alleles (gene swamping) in
M. larici-populina populations evolving on the wild host.