The ITS region is a reliable character in the taxonomic distinction of Fusarium verticillioides and F. proliferatum

F. verticillioides and F. proliferatum are morphologically very similar pathogens of maize. For this reason, F. proliferatum isolates have been often erroneously attributed to the ex-species F. moniliforme (the former name of F. verticillioides). The only accepted marker for these morphospecies is the possible (but not exclusive) formation of polyphialides in F. proliferatum but not F. verticillioides; both produce microconidia in chains. A collection of 100 isolates from maize grown in North-western Italy were assigned either to F. verticillioides or F. proliferatum by morphological observation. This approach requires considerable expertise, and must be integrated with sexual and molecular analyses. We performed sexual crosses, ITS and calmodulin sequencing as well as AFLP on a subset of isolates, and ITS-RFLP on all of them. We propose that the ITS region be considered taxonomically relevant for the phylogenetic distinction of these two species. Indeed ITS-RFLP, as well as a pair of primers designed on conserved polymorphisms associated to either species within this region, could rapidly and very reliably discriminate between F. proliferatum and F. verticillioides isolates, once they were examined for the presence of conidial chains to exclude F. subglutinans isolates. These primer pairs add to the toolbox of the fungal taxonomists interested in species discrimination among Fusarium pathogens of maize.