Résumé
Many cryptic species have recently been discovered in fungi, especially in
fungal plant pathogens. Cryptic fungal species co-occurring in sympatry
may occupy slightly different ecological niches, for example infecting the
same crop plant but specialized on different organs or having different
phenologies. Identifying cryptic species in fungal pathogens of crops and
determining their ecological specialization is therefore crucial for
disease management. Here we addressed this question in the ascomycete
Botrytis cinerea, the agent of grey mold on a wide range of plants. On
grape, B. cinerea causes severe damages but is also responsible for noble
rot used for processing sweet wines. We used microsatellite genotyping and
clustering methods to elucidate whether isolates sampled on grey mold vs.
noble rot symptoms in three French regions belong to genetically
differentiated populations. The inferred population structure matched
geography rather than the type of symptom. Noble rot symptoms therefore do
not seem caused by a specific B. cinerea population but instead seem to
depend essentially on microclimatic conditions, which has applied
consequences for the production of sweet wines.