GENERALIZATION OF QOI RESISTANCE OF ZYMOSEPTORIA TRITICIIH NORTHERN FRANCE

摘要

Septoria tritici blotch caused by the fungal ascomycete Zymoseptoria tritici is one of the most frequently occurring diseases on wheat crops worldwide. Since host resistance is not completely effective in most wheat cultivars, disease control mainly relies on the use of fungicides. Strobilurins, also referred as Qui-none outside Inhibitors (Qols), have been extensively used just after their introduction in 1996 to control Z. tritici. Unfortunately, such a use rapidly led to the emergence and widespread of Qol resistance in most European countries, including France. However, no precise information is currently available on the actual occurrence of Qol resistance within the French populations of the pathogen. The aim of the present study was thus to assess the evolution of Z. tritici Qol resistance in northern France using a collection of 763 strains isolated between 2009 and 2015 (32 in 2009, 166 in 2011, 337 in 2012 and 228 in 2015). Qol resistance was assessed by screening the cytochrome b G143A substitution conferring Qol resistance, using a PCR-based mismatch mutation assay. Among the 763 assessed strains, 760 were found out to possess the A143 resistant allele, thus only three of them were found to carry the G143 sensitive allele. Such a finding highlights a total generalisation of Z. tritici Qol resistance in Northern France and suggests to continue the use of other fungicide classes to control Septoria tritici blotch.