Résumé
Understanding how pathogens emerge is essential to bring disease-causing
agents under durable human control. Here, we used cross-pathogenicity
tests to investigate changes in life history traits of the fungal pathogen
Venturia inaequalis associated with host-tracking during the domestication
of apple and subsequent host range expansion on the wild European
crabapple (Malus sylvestris). Pathogenicity of 40 isolates collected in
wild and domesticated ecosystems were assessed on the domesticated apple,
its central Asian main progenitor (M. sieversii) and M. sylvestris.
Isolates from wild habitats in the centre of origin of the crop were not
pathogenic on the domesticated apple and less aggressive than other
isolates on their host of origin. Isolates from the agro-ecosystem in
central Asia infected a higher proportion of plants with higher
aggressiveness, on both the domesticated host and its progenitor. Isolates
from the European crabapple were still able to cause disease on other
species but were less aggressive and less frequently virulent on these
hosts than their endemic populations. Our results suggest that the
domestication of apple was associated with the acquisition of virulences
in the pathogen following host-tracking. The spread of the disease in the
agro-ecosystem would also have been accompanied by an increase in overall
pathogenicity.