AN USTILAGIO-MAYDIS MUTANT PARTIALLY BLOCKED IN P450(14DM) ACTIVITY IS HYPERSENSITIVE TO AZOLE FUNGICIDES

An Ustilago maydis ergosterol biosynthesis mutant (A14) which is parti ally blocked in sterol 14 alpha-demethylase (P450(14DM)) activity is d escribed, This mutant accumulated the abnormal 14 alpha-methyl sterols , eburicol, 14 alpha-methylfecosterol, and obtusifoliol, along with si gnificant amounts of ergosterol, Although the A14 mutant grew nearly a s well as the wild type, it was impaired in cell extension growth, whi ch indicated a dysfunction in apical cell wall synthesis, The mutant w as also found to be hypersensitive to the azole fungicides penconazole and tebuconazole. (C) 1996 Academic Press, Inc.