Sterol composition of mycelia of the plant pathogenic ascomycete Leptosphaeria maculans

Analysis of sterols in mycelia of the ascomycete, Leptosphaeria maculans by gas chromatography-mass spectrometry revealed that ergosterol comprised 95% of the total sterols, with eight other sterols comprising the remaining 5%. Six of these latter sterols were putative precursors of ergosterol and their presence suggested a pathway for ergosterol biosynthesis in this fungus. Ergosterol biosynthesis in fungi is inhibited by the triazole antifungal agent flutriafol. When L. maculans was grown in the presence of flutriafol, ergosterol content decreased while two 14 alpha-methylated sterols, 24-methylene dihydrolanosterol and obtusifoliol, accumulated.