Pattern and causes of the establishment of the invasive bacterial potato pathogen Dickeya solani and of the maintenance of the resident pathogen D. dianthicola
Résumé
Invasive pathogens can be a threat when they affect human health, food production or ecosystem
services, by displacing resident species, and we need to understand the cause of their
establishment. We studied the patterns and causes of the establishment of the pathogen Dickeya
solani that recently invaded potato agrosystems in Europe by assessing its invasion dynamics
and its competitive ability against the closely-related resident D. dianthicola species.
Epidemiological records over one decade in France revealed the establishment of D. solani and
the maintenance of the resident D. dianthicola in potato fields exhibiting blackleg symptoms.
Using experimentations, we showed that D. dianthicola caused a higher symptom incidence on
aerial parts of potato plants than D. solani, while D. solani was more aggressive on tubers (i.e.
with more severe symptoms). In co-infection assays, D. dianthicola outcompeted D. solani in
aerial parts, while the two species co-existed in tubers. A comparison of 76 D. solani genomes
(56 of which having been sequenced here) revealed balanced frequencies of two previously
uncharacterized alleles, VfmBPro and VfmBSer, at the vfmB virulence gene. Experimental
inoculations showed that the VfmBSer population was more aggressive on tubers while the
VfmBPro population outcompeted the VfmBSer population in stem lesions, suggesting an important
role of the vfmB virulence gene in the ecology of the pathogens.This study thus brings novel
insights allowing a better understanding of the pattern and causes of the D.solani invasion into
potato production agrosystems, and the reasons why the endemic D.dianthicola nevertheless
persisted.
Domaines
Sciences du Vivant [q-bio]
Origine : Fichiers produits par l'(les) auteur(s)