Assessment of trichothecene chemotypes of Fusarium culmorum occurring in Europe

Abstract

Fusarium trichothecenes are a group of fungal toxic metabolites whose synthesis requires the action of gene products from three different genetic loci. We evaluated, both chemically and by PCR assays, 55 isolates of Fusarium culmorum from eight European countries and different host plants for their ability to produce trichothecenes. Specific sequences in the Tri6–Tri5 intergenic region were associated with deoxynivalenol production. Sequences in the Tri3 gene were also associated with deoxynivalenol production and specific primer sets were selected from these sequences to identify 3–acetyl–deoxynivalenol or 15–acetyl–deoxynivalenol chemotypes. Specific sequences in the Tri5 and Tri7 genes were associated with the nivalenol chemotype but not with the deoxynivalenol chemotype. Two chemotypes were identified by chemical analysis and confirmed by PCR. Strains of the nivalenol chemotype produced nivalenol (up to 260 µg g⁻¹) and 4–acetyl–nivalenol (up to 60 µg g⁻¹), strains with the 3–acetyl–deoxynivalenol chemotype produced deoxynivalenol (up to 1700 µg g⁻¹) and 3–acetyl–deoxynivalenol (up to 600 µg g⁻¹). Three strains of F. culmorum from France, previously reported as 15–acetyl–deoxynivalenol producers, had the 3–acetyl–deoxynivalenol chemotype. The results are consistent with data from other European countries on the occurrence of the nivalenol and 3–acetyl–deoxynivalenol chemotypes and provide support for the hypothesis that European isolates of F. culmorum producing deoxynivalenol belong only to the 3–acetyl–deoxynivalenol chemotype. The production of trichothecenes from F. culmorum isolates from walnut (3–acetyl–deoxynivalenol chemotype) and leek (nivalenol chemotype) is reported for the first time.

Keywords:

• Fusarium culmorum
• deoxynivalenol
• nivalenol
• trichothecenes
• chemotypes
• PCR primers
• mycotoxins

Acknowledgements

The authors thank Antonio Logrieco for critically reading the manuscript, Giuseppe Cozzi and Filomena Epifani for technical assistance, and the following colleagues for providing fungal isolates: Jerry Chelkowski, Polish Academy of Sciences, Poznan, Poland; Laetitia Pinson-Gadais, INRA, Bordeaux, France; Misericordia Imenez, University of Valencia, Spain; Mona Torp, National Veterinary Institute, Oslo, Norway; and Cees Waalwijk, Plant Research International, Wageningen, the Netherlands. This work was supported in part by the Italian Ministry of Education, University and Research (MIUR), SINSIAF PON project – Law 297/2000.