Étude des traits d'histoire de vie de "Melampsora larici-populina", agent de la rouille du peuplier : de leur déterminisme génétique à leurs conséquences évolutives

Abstract : Adaptation of a phytopathogenic fungus to its environment, as well as the resulting evolution and structuration of its populations, are strongly influenced by its life history traits which condition its fitness. This is illustrated here with the poplar rust fungus Melampsora larici-populina. Hence, we showed that spore volume repeatedly evolved through natural selection, during annual epidemics in the Durance River valley, showing the implication of this trait in the fungus adaptive processes. Consequently, genetic constraints conditioning the adaptive potential of the fungus, in connection with life history traits, were studied in laboratory, over a progeny resulting from a selfing of a reference strain. Results suggest that M. larici-populina has a high adaptive potential. Finally, a high resolution genetic map of the fungus, comprising 18 chromosomes, has been built in order to study genetic determinism of these traits. One locus of virulence and three QTL involved in the expression of the lesion size were detected and accurately mapped on this map. This work emphasizes the role of quantitative traits in adaptation and structuration of M. larici-populina populations in response to the environmental selective pressures, by conferring an adaptive potential, the basis of organisms’ adaptation. It also opens many opportunities to identify the genetic bases of adaptation of this fungus, these elements being essential for the development of sustainable strategies of disease control
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Michaël Pernaci. Étude des traits d'histoire de vie de "Melampsora larici-populina", agent de la rouille du peuplier : de leur déterminisme génétique à leurs conséquences évolutives. Sciences agricoles. Université de Lorraine, 2015. Français. ⟨NNT : 2015LORR0064⟩. ⟨tel-01751695⟩

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