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Pattern and causes of the establishment of the invasive bacterial potato pathogen Dickeya solani and of the maintenance of the resident pathogen D. dianthicola
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  • Pauline Blin,
  • Kévin Robic,
  • Slimane Khayi,
  • Jérémy Cigna,
  • Euphrasie Munier,
  • Pauline Dewaegeneire,
  • Angélique Laurent,
  • Yan Jaszczyszyn,
  • Kar-Wai Hong,
  • Kok-Gan Chan,
  • Amélie Beury,
  • sylvie Reverchon-Pescheux,
  • Tatiana Giraud,
  • Valérie Hélias,
  • Denis Faure
Pauline Blin
CNRS

Corresponding Author:[email protected]

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Kévin Robic
French Federation of Seed Potato Growers
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Slimane Khayi
CNRS
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Jérémy Cigna
French Federation of Seed Potato Growers
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Euphrasie Munier
French Federation of Seed Potato Growers
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Pauline Dewaegeneire
French Federation of Seed Potato Growers
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Angélique Laurent
French Federation of Seed Potato Growers
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Yan Jaszczyszyn
CNRS
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Kar-Wai Hong
Jiangsu University
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Kok-Gan Chan
Jiangsu University
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Amélie Beury
French Federation of Seed Potato Growers
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sylvie Reverchon-Pescheux
INSA Lyon
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Tatiana Giraud
Université Paris-Sud
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Valérie Hélias
French Federation of Seed Potato Growers
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Denis Faure
CNRS
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Abstract

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 advantages or disadvantages 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 was more aggressive than D.solani on aerial parts, while D.solani was more aggressive on tubers. In co-infection assays, D.dianthicola outcompeted D.solani in aerial parts, while D.solani and D.dianthicola co-existed in tubers. A comparison of 76 D.solani genomes (56 of which having been sequenced here) revealed balanced frequencies of two uncharacterized alleles, VfmBPro and VfmBSer, at the vfmB virulence gene. Experimental inoculations showed that the VfmBSer population was more aggressive on tubers, while VfmBPro and VfmBSer populations exhibited a similar aggressiveness on stems. In stem co-infections, the VfmBPro population outcompeted the VfmBSer population, while they co-existed in tubers. 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 D.dianthicola nevertheless persisted. More broadly, this study contributes to our understanding the ecological determinants of pathogen invasion and of the conditions for the maintenance of endemic competitors.
Jan 2021Published in Molecular Ecology volume 30 issue 2 on pages 608-624. 10.1111/mec.15751