Hanne Lindhard Pedersen

Emergence of new virulent populations of apple scab from nonagricultural disease reservoirs

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  • Christophe Lemaire, University of Nantes Angers Le Mans
  • ,
  • Marie De Gracia, Institut National de Recherche Agronomique (INRA)
  • ,
  • Thibault Leroy, Institut National de Recherche Agronomique (INRA)
  • ,
  • Monika Michalecka, Inst Hort
  • ,
  • Hanne Lindhard-Pedersen
  • Fabien Guerin, University of La Reunion
  • ,
  • Pierre Gladieux, CIRAD
  • ,
  • Bruno Le Cam, Institut National de Recherche Agronomique (INRA)

Plant pathogens adapt readily to new crop varieties in agrosystems, and it is crucial to understand the factors underlying the epidemic spread of new virulent strains if we are to develop more efficient strategies to control them.

In this study we used multilocus microsatellite typing, molecular epidemiology tools and a large collection of isolates from cultivated, wild and ornamental apples to investigate the origin of new virulent populations of Venturia inaequalis, an ascomycete fungus causing apple scab on varieties carrying the Rvi6 resistance gene.

We demonstrated a common origin at the European scale of populations infecting apples (Malus 9 domestica) carrying the Rvi6 resistance and Malus floribunda, the progenitor of the Rvi6 resistance. Demographic modeling indicated that the Rvi6-virulent lineage separated several thousands of years ago from populations infecting non-Rvi6 hosts, without detectable gene flow between the two lineages.

These findings show that 'breakdowns' of plant resistance genes can be caused by the selection and migration of virulent genotypes from standing genetic variation maintained in environmental disease reservoirs, here ornamental crabapples. This work stresses the need to take better account of pathogen diversity in resistance screenings of breeding lines and in resistance deployment strategies, in order to enhance sustainable disease management.

TidsskriftNew Phytologist
Sider (fra-til)1220-1229
Antal sider10
StatusUdgivet - feb. 2016

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