232 Fig. 2 Colony diameter of the strains used in the study after four days of culturing on potato dextrose agar (PDA) medium at room temperature (mean of two replicates) J Appl Genetics (2012) 53:227–236 the TRI5 gene and two alleles of the TRI13 gene, associated with deoxynivalenol and nivalenol chemotypes). In case of the esyn1 gene, encoding enniatin synthetase, we could iden- tify it only in the strain of F. avenaceum ITEM 2753. Also, we did not find any amplification products from the strains of F. equiseti using primers specific for TRI13DON and TRI13NIV markers, which suggests the inability of those strains to pro- duce DON or NIV. F. graminearum strains KF 1413 and KF 371, exhibiting DON and NIV chemotypes, respectively, am- plified the expected amplicons (results not shown). Since F. equiseti has often been reported as a group A trichothecene producer, we screened the studied strain set for the presence of the TRI5 gene and an allele of the TRI4 gene specific for A-trichothecene producers (Nicholson et al. 2004). Only 14 of the strains possessed the TRI5 gene: 13 F. equiseti genotypes and KF 2640 F. langsethiae strain (Table 1). The amplified fragments were used to read the sequences, which served as the basis for phylogenetic tree construction (Fig. 5). All the obtained TRI5 sequences were submitted to the NCBI GenBank and are publicly available under accession numbers JF966257–JF966272. Discussion The results of the species-specific DNA marker identifica- tion showed that the set of F. equiseti isolates used in the study reveals a high level of intra-specific polymorphism. Nine of 25 isolates tested did not amplify the expected amplicon (Table 1). There was no correlation between the country of origin and the presence of the marker fragment. The marker was designed on the basis of the highly variable ITS region of nuclear ribosomal DNA (Mishra et al. 2003), s o i t s e e m s l i ke l y t h a t i t d i s p l ay s i n t r a - s p e c i f i c Fig. 3 Zearalenone (ZEA) production by Fusarium equiseti isolates used in this study