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Poster: Epidemiology: Population Biology Genetics


Population structure of the wheat pathogen Zymoseptoria tritici in France at different scales
A. SIAH (1), L. EL CHARTOUNI (2), B. TISSERANT (2), P. HALAMA (1), P. REIGNAULT (3) (1) Institut Charles Viollette (EA 7394), Institut Supérieur d’Agriculture, France; (2) Unité de Chimie Environnementale et Interactions sur le Vivant (EA 4492), Universit

Zymoseptoria tritici is currently the most damaging disease on wheat crops in Europe, especially in France, where it causes each year 1.7 t/ha yield loss in average. In order to better understand its genetic features, we characterized several Z. tritici populations (more than 1500 isolates), isolated in France over a ten-year period (2005-2015) and at different spatial scales (whole country, Nord-Pas de Calais region, field, 30 cm2 square, plant, leaf and lesion) using SSR markers and mating type idiomorphs. Results revealed high and similar levels of genic and genotypic diversities at the country, region and field scales, but the diversity values gradually decreased from the field to finer scales such as plant, leaf and lesion. Bayesian and non-Bayesian statistical analyses revealed significant structuration of the global French population into three genetic clusters, and the Nord-Pas de Calais population into three sub-clusters, all distributed according to their geographical origin. However, no differentiation was found at finer scales. Both mating types were found at equal proportions at the country, region and field scales and co-occurred at all other investigated scales. This study highlighted for Z. tritici in France a high potential for sexual reproduction and genetic diversification, as well as a structuration of its populations at largest scales, agreeing with its high fitness degree and its ability of adaptation to local agro-climatic conditions.