Fusarium oxysporum f. sp. cyclaminis: underestimated genetic diversity
2016
Lecomte, Charline | Edel-Hermann, Véronique | Cannesan, Marc-Antoine | Gautheron, Nadine | Langlois, Agnès | Alabouvette, Claude | Robert, Fabien | Steinberg, Christian
Fusarium oxysporum f. sp. cyclaminis (Focy) is the most damaging pathogen of cyclamen (Cyclamen persicum). Control measures are limited and not efficient enough to ensure a healthy production. The development of a tool allowing the early detection of Focy and an effective control method relies on the knowledge of Focy diversity. We obtained 27 Focy strains from international collections, and recovered 24 additional F. oxysporum isolates from cyclamen. A pathogenicity test revealed 15 pathogenic isolates out of the 24 isolates from cyclamen, with substantial differences in aggressiveness among isolates. The other nine were non-pathogenic endophytic strains of cyclamen. We described the genetic diversity of pathogenic and non-pathogenic strains by sequencing part of the translation elongation factor 1-α gene and the full-length nuclear ribosomal intergenic spacer region. We found high genetic diversity within the forma specialis, with 42 Focy strains distributed into six two-locus sequence types (ST). No relationship was found between genotypic grouping, geographic origin and aggressiveness within the collection of strains. Genetic diversity was much higher among non-pathogenic strains: the nine strains were distributed into nine ST, all of them distinct from pathogenic ST. As both pathogenic strains and endophytic strains can be present in cyclamen, an efficient tool to detect Focy is badly needed.
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