234 from Southern (i.e. warmer) locations will have an optimum temperature higher than those from temperate climate (PL population). Kosiak et al. (2005) recorded similar colony sizes (39–68 mm) for Norwegian isolates as those observed in this study for Polish ones. Canadian isolates from ginseng fields displayed the fastest growth at about 26°C (Punja et al. 2008), which seems to be in good agreement with our data. The ITEM 3699 strain was the only one that produced carmine reddish pigment in a PDA culture (results not shown). Having analysed the morphology of conidia and mycelium, and taking the tef-1α sequence into consideration, it seems likely that the strain represents F. langsethiae rather than F. equiseti. ITEM 6164 strain’s morphology is more typical to F. equiseti, but after the strain was subjected to further investigation by analysing the mycotoxin biosynthetic genes TRI5 and PKS13 (Figs. 4 and 5), it appeared that it probably represents F. sporotrichioides. There are only a few publications on the biosynthesis of ZEA by F. equiseti because, until recently, the species was considered as being unable to synthesise ZEA, and its main metabolites were fusarochromanone and trichothecenes (Marasas et al. 1984; Morrison et al. 2002). According to Bosch and Mirocha (1992), ZEA was detected in 8 of the 23 tested isolates of F. equiseti at concentrations between 55 and 3,433 μg/g. Two of them were lethal to rats, although in culture extracts, the only toxin found was ZEA, at concentrations of 567 and 232 μg/g, respectively. According to Langseth et al. (1998–1999), who examined mycotoxin production by F. equiseti isolated from Norwegian cereals, three isolates pro- duced ZEA in the range 0.1 to 3 μg/g. Kosiak et al. (2005) also found ZEA in all 25 examined isolates of F. equiseti, but only 14 of them synthesised this toxin in substantial amounts. Concerning the relatively high level of ZEA biosynthesis by IT strains (Fig. 3), it seems unexpected that most of them did not amplify PKS4 and PKS13 genes (Table 1). On the contrary, Polish isolates, which generally produced less toxin, showed the presence of both genes, with only one exception (KF 13 did not amplify the PKS13 gene). Obvi- ously, all strains that produce ZEA are supposed to carry PKS genes, despite the negative PCR results. This inconsis- tency may be explained by the fact that the primers were designed on the basis of F. graminearum gene sequences, so a significant level of inter-specific divergence is possible. Specific markers for the reliable identification of PKS genes from F. equiseti will be created for future research on the basis of the sequences obtained. Interestingly, similar differ- entiation of both populations can be visible in the case of TRI5 gene identification. Almost all Polish isolates dis- played the presence of the gene, while the Italian isolates did not (Table 1). Again, in the case of the PKS13 sequence, the ITEM 6164 strain appeared as being different from the other strains of F. equiseti, grouping with F. graminearum (Fig. 4) with a similarity level exceeding 90%. J Appl Genetics (2012) 53:227–236 The abilities of all strains to produce other toxins, such as enniatins and trichothecenes, were analysed by identifying the genes involved in two metabolic pathways. Those were: enniatin synthase gene esyn1, trichodiene synthase gene TRI5, together with TRI4 marker specific for group A tricho- thecene producers and TRI13-based markers distinguishing deoxynivalenol and nivalenol chemotypes among trichothe- cene producers (Nicholson et al. 2004). The esyn1 gene was present only in the ITEM 2753 strain of F. avenaceum, which is the species considered as one of the major pro- ducers of this mycotoxin group (Jestoi et al. 2004; Langseth et al. 1998–1999; Logrieco et al. 2002). However, since F. equiseti often produces beauvericin and both cyclohexadep- sipeptides (beauvericin and enniatins) share a common bio- synthetic pathway, there is a strong possibility that the species possess some form of the synthetase encoded by the esyn1 gene homologue. Experimental work to prove its presence in F. equiseti using newly designed primers is currently being carried out. Also, both markers amplifying portions of the TRI13 gene gave no amplification from all the strains tested, which should be regarded as the inability to produce DON or NIV by F. equiseti. Actually, the lack of DON/NIV chemotype markers suggests the ability to synthesise group A trichothe- cenes, like scirpentriol, MAS or DAS, which are, in fact, often produced by this species (Kosiak et al. 2005). TRI4 marker was found in only three strains of F. equiseti and one F. langsethiae strain (Table 1). This is likely a result of inter- specific sequence divergence between F. graminearum and F. equiseti; however, the marker, despite being described as ”generic”, has not yet been tested on F. equiseti isolates to prove its reliability (Nicholson et al. 2004). Weak amplifica- tion fragments obtained in the present work will serve as templates to design species-specific TRI4 markers. We found the TRI5 gene present in almost all strains from the Polish population and only in a few isolates originating from Italy (Table 1). Two of them (KF 2650 and 2651), though described as Italian strains, based on the tef-1α and TRI5 sequence comparisons, are placed firmly inside the clade of Polish isolates (Figs. 1 and 5). Also, the speed of their growth resembles the PL strains rather than the IT ones. When tef-1α and TRI5 dendrograms were compared, two distinct groups of PL isolates from the tef-1α tree seem to be more dispersed when the TRI5 sequence is analysed. It can be concluded that the Polish strain set used in our study was less uniform than the Italian set, although more isolates should be added to the analyses we have presented here in order to support this hypothesis. Two other strains (ITEM 3699 and ITEM 6164) were already highlighted on the basis of the partly controversial results of the sequence analysis (Figs. 1 and 4). They formed a separate branch on the TRI5 tree, being more closely related to F. langsethiae (KF 2640) and F. graminearum variants (KF 1413 and KF 371), as well as to the F. sporotrichioides sequences of TRI5 present in