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- Title
The mechanism of resistance to sterol 14alpha demethylation inhibitors in a mutant (Erg 40) of Ustilago maydis
- Authors
Zhou, M. G.; Butters, J. A.; Hollomon, D. W.
- Abstract
Resistance to DMI fungicides is a problem in both agriculture and medicine. Several mechanisms of resistance exist, but, as yet, few havebeen characterised in field resistant strains of plant pathogens. One approach to evaluating the role of mutations in the sterol 14 alphademethylase (14DM) target site requires cloning this gene and confirming its identity by complementation in an appropriate mutant. The azole-resistant mutant, Erg 40, of Ustilago maydis which is totally blocked at the 14 alpha demethylation step in sterol biosynthesis seems to be suitable for such expression studies. Transformation of Erg 40 with a plasmid containing the yeast 14 alpha demethylase (CYP51A1) gene removed the block in sterol biosynthesis and generated azole-sensitive transformants. Detailed analysis of these transformants failed to detect the presence of the yeast gene and suggested, instead, that changes in sterol biosynthesis resulted simply from the transformation protocol and not from the incorporation of extracellular DNA. Subsequent sequence analysis has revealed a mutation in the 14 alpha demethylase gene of Erg 40. The results suggest that azole resistance in Erg 40 is not simply controlled by this mutation but involves some additional regulatory function, and consequently Erg 40 is not suitable for complementation studies with CYP51A1 genes.
- Subjects
AGRICULTURE; BOTANY; FUNGI; PLANTS; USTILAGO maydis
- Publication
Pest Management Science, 2000, Vol 56, Issue 3, p257
- ISSN
1526-498X
- Publication type
Article