Fusarium incarnatum-equiseti species complex occurring on durum wheat in Southern Italy

A survey of fungal diversity associated with Fusarium crown rot of durum wheat in Southern Italy led to isolation of multiple Fusarium species. Strains belonging to the Fusarium incarnatum equiseti species complex (FIESC) were the second most frequently isolated group. The FIESC comprises over 30 phylogenetic species, most of which are cryptic and lack formal Latin names, making identification challenging. If FIESC strains are indeed pathogenic, their high frequency should be considered in field disease management and when evaluating mycotoxin contamination risks. Pathogenicity tests performed with 29 isolates showed a variable level of virulence (disease severity index range 0÷38%, on a 0-100 scale), with 13.4% average. Using single-gene phylogeny based on translation elongation factor 1-alpha, we identified 74 Fusarium strains belonging to 7 FIESC species. Based on phylogenetic analyses, strains have been shown to belong to F. clavum (63), F. flagelliforme (1), F. croceum (1), F. guilinense (1), F. coffeatum (3), F. tanahbumbuense (3) and the recently described Fusarium mariecurieae (2), here reported in Italy for the first time. To investigate the potential of F. mariecurieae to produce trichothecenes, a primer pair, targeting conserved regions of the TRI1 gene, was designed. An amplification fragment was obtained, and homologous sequences were assessed for the 2 isolates. Since the trichothecene cluster is reported in various FIESC members, and variation in the TRI gene cluster content can influence trichothecene analogue production, additional studies are necessary to confirm whether F. mariecurieae produces trichothecenes or other mycotoxins, and to evaluate its impact on food safety.