Reports of introns
led to reservations among mycologists for using this gene
as a phylogenetic marker orfor DNA barcoding (Rossman
2007). If introns are frequent and of significant length, they
would interfere with PCR by disrupting priming sites
or increasing amplicon length. However, in the first comprehensive study of COX1in a fungal group, Penicillium
subgenus Penicillium(Seifert et al. 2007), introns were found
in only about 1% of 360 strains. A subsequent study of a
smaller genus in a different taxonomic order, Leohumicola,
reported only 5% of sampled cultures with introns (Nguyen
& Seifert 2008)