PCR-based detection of sterol demethylation inhibitor-resistant strains of Penicillium digitatum

A simple method for detecting sterol demethylation inhibitor (DMI)-resistant strains of the citrus green mould pathogen, Penicillium digitatum, has been developed. The method involves detection of a tandem repeat of a transcriptional enhancer in the promoter region of PdCYP51, which encodes the target enzyme of DMIs, by PCR, using conidia as template. The presence of the tandem repeat leads to overexpression of this gene and confers DMI resistance to the fungus. We examined the relationship between the presence of the tandem repeat and DMI resistance in 39 strains of P digitatum. The results suggested that the DMI resistance mechanism based on the tandem repeat is common in this fungus. Using this method, the presence of DMI resistance of this fungus can be detected within 5-6 h. (C) 2001 Society of Chemical Industry.