Cyclic hexadepsipeptides in wheat field samples andesyn1 gene divergence among enniatin producingFusarium avenaceum strains

Abstract

Fusarium avenaceum is one of the most important pathogenic species in agricultural and forest environments of moderate climate, particularly in cereals and legume pulse crops. Numerous mycotoxins can be synthesized by the species, with moniliformin and enniatins (ENN) being the prevailing metabolites. The aims of this work were to examine the amounts of ENN and beauvericin present in naturally contaminated field samples of wheat kernels and chaffs collected in Poland in 2005 and 2009 from heads infected withF. avenaceum, and to reveal the divergence of theesyn1 gene amongF. avenaceum strains of different origin. ENN-B and ENN-B1 were the major metabolites identified in wheat field samples. Chaff fractions contained significantly more mycotoxins than grain. Samples originating from 2005 were in general less contaminated with ENN than those from the 2009 season. The highest amount of ENN-B found in grain was 28,520 μg/kg. Beauvericin was only found in trace amounts in all the samples tested.F. avenaceum strains isolated from the analysed wheat samples were identified using species-specific DNA marker and translation elongation factor 1α (tef-1α) sequence analysis. A higher level of sequence polymorphism was revealed for the enniatin synthetase (esyn1) gene than ecorded bytef-1α analysis. Moreover, species known to be typical beauvericin producers, e.g.Fusarium oxysporum andFusarium proliferatum, were clustered into a separate branch on the dendrogram, apart from the strains of ENN-producing species, i.e.F. avenaceum andFusarium scirpi.