Production of petasol by Drechslera gigantea in liquid culture

Drechslera gigantea, the causative agent of zonate eyespot disease on grasses, produces at least twelve bioactive eremophilanes. Their structures have been recently elucidated using conventional spectroscopy and X-ray crystallography. A study to examine the production of one of these eremophilanes, petasol, by D. gigantea grown in liquid culture was undertaken. A procedure using high performance liquid chromatography to quantify petasol levels in culture filtrates of D. gigantea was developed. This procedure was used to study petasol production by D. gigantea under different cultural conditions. Leaf material from quackgrass ( Agropyron repens), a host of the fungus, stimulated petasol production. Amendments such as l-leucine or the sterol biosynthesis inhibitor chloro-choline chloride (CCC) also exhibited stimulatory activity.