INCREASED RESISTANCE TO 14-ALPHA-DEMETHYLASE INHIBITORS (DMIS) IN ASPERGILLUS-NIGER BY COEXPRESSION OF THE PENICILLIUM-ITULICUM EBURICOL 14-ALPHA-DEMETHYLASE (CYP51) AND THE ASPERGILLUS-NIGER CYTOCHROME-P450 REDUCTASE (CYRA) GENES

In this paper we describe the effects of over-expression of the Penici llium italicum gene encoding eburicol 14 alpha-demethylase (cyp51), in Aspergillus niger strains with one or multiple copies of the gene enc oding cytochrome P450 reductase (cprA), on the eburicol 14 alpha-demet hylase activity. Eburicol 14 alpha-demethylase activity was determined by measuring the resistance of transformants against some eburicol 14 alpha-demethylase inhibitors (DMIs). DMIs are widely used as fungicid es in crop protection and human and veterinarian health care. DMI resi stance in a transformant overexpressing both CPR and CYP51 was increas ed 5-30-fold compared to DMI resistance in the wild type strain, depen ding on the test compound used. Resistance in this strain was approxim ately 2-5-fold increased compared to DMI resistance in a transformant that was overexpressing the cyp51 gene but had only the wild type copy of the cprA gene and approximately 3-12-fold increased compared to a strain overexpressing the cprA gene (and having only the wild type cop y of the cyp51 gene). These results show the importance of CPR overexp ression for increasing cytochrome P450 activities in filamentous fungi .