New smut-specific primers for the ITS barcoding of Ustilaginomycotina

The smut fungi (Ustilaginomycotina) are a highly diverse group, containing about 115 genera and 1700 species, most of which are biotrophic plant pathogens. As for other fungal groups, the ITS rDNA region is widely used to determine smut fungi at species level due to its high discriminatory power and for phylogenetic reconstructions within genera. So far, two primer sets, ITS1/ITS4 and M-ITS1/ITS4, were generally used to amplify smut fungi, but these often co-amplify host plants or contaminant fungi and do not yield satisfactory amplification for a variety of smut fungi. In the present study, based on a selection of genera that include more than 90% of the species of smut fungi (more than half of the genera of smut fungi), three new primers, smITS-F, smITS-R1 and smITS-R2, situated in the SSU or LSU region, were designed to avoid the amplification of host plants and to extend the coverage of PCR amplification for as many smut genera as possible.