title: Local adaptation to temperature in populations and clonal lineages of the Irish potato famine pathogen Phytophthora infestans.
abstract: Environmental factors such as temperature strongly impact microbial communities. In the current context of global warming, it is therefore crucial to understand the effects of these factors on human, animal, or plant pathogens. Here, we used a common-garden experiment to analyze the thermal responses of three life-history traits (latent period, lesion growth, spore number) in isolates of the potato late blight pathogen Phytophthora infestans from different climatic zones. We also used a fitness index (FI) aggregating these traits into a single parameter. The experiments revealed patterns of local adaptation to temperature for several traits and for the FI, both between populations and within clonal lineages. Local adaptation to temperature could result from selection for increased survival between epidemics, when isolates are exposed to more extreme climatic conditions than during epidemics. We also showed different thermal responses among two clonal lineages sympatric in western Europe, with lower performances of lineage 13_A2 compared to 6_A1, especially at low temperatures. These data therefore stress the importance of thermal adaptation in a widespread, invasive pathogen, where adaptation is usually considered almost exclusively with respect to host plants. This must now be taken into account to explain, and possibly predict, the global distribution of specific lineages and their epidemic potential.
authors.affiliation: INRA UMR IGEPP (Institute for Genetics, Environment and Plant Protection) 35653 Le Rheu Cedex France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Mariette
authors.affiliation: INRA UMR IGEPP (Institute for Genetics, Environment and Plant Protection) 35653 Le Rheu Cedex France.
authors.forename: Annabelle
authors.initials: A
authors.lastname: Androdias
authors.affiliation: INRA UMR IGEPP (Institute for Genetics, Environment and Plant Protection) 35653 Le Rheu Cedex France.
authors.forename: Romain
authors.initials: R
authors.lastname: Mabon
authors.affiliation: INRA UMR IGEPP (Institute for Genetics, Environment and Plant Protection) 35653 Le Rheu Cedex France.
authors.forename: Roselyne
authors.initials: R
authors.lastname: Corbière
authors.affiliation: INRA UMR IGEPP (Institute for Genetics, Environment and Plant Protection) 35653 Le Rheu Cedex France.
authors.forename: Bruno
authors.initials: B
authors.lastname: Marquer
authors.affiliation: INRA UMR IGEPP (Institute for Genetics, Environment and Plant Protection) 35653 Le Rheu Cedex France.
authors.forename: Josselin
authors.initials: J
authors.lastname: Montarry
authors.affiliation: INRA UMR IGEPP (Institute for Genetics, Environment and Plant Protection) 35653 Le Rheu Cedex France.
authors.forename: Didier
authors.initials: D
authors.lastname: Andrivon
keywords: Climate change; epidemic; late blight; life‐history traits; phenotypic plasticity; plant pathogen; temperature adaptation