Impact of changes in the target P450 CYP51 enzyme associated with altered triazole-sensitivity in fungal pathogens of cereal crops

Control of diseases caused by fungi in both medicine and agriculture is heavily dependent on the use of
triazoles. As a consequence, resistance to triazoles is a threat to both human health and the sustainability of
agricultural production systems. In human pathogens, particularly Candida albicans, mutations encoding
alterations in the target cytochrome P450 sterol 14α-demethylase (CYP51; where CYP is cytochrome
P450) enzyme are the primary determinants of triazole resistance. In fungal pathogens of cereals, CYP51A1
modifications, some at positions known to contribute to a resistant phenotype in human pathogens, have
also been identified in isolates with altered triazole-sensitivity. However, unlike medicine where resistance
to triazoles is a major clinical problem, failures of triazoles to control crop diseases in the field are rare with
mean population sensitivities generally remaining low, perhaps due to differences in the selection pressures
imposed on human and cereal pathogen populations. Nonetheless, the biological potential for resistance
exists, and the question remains as to whether widespread triazole resistance can develop in an important
cereal pathogen