Glisoprenin A, an inhibitor of the signal transduction pathway leading to appressorium formation in germinating conidia of Magnaporthe grisea on hydrophobic surfaces

Glisoprenin A, a fungal metabolite obtained from submerged cultures of Gliocladium roseum, interfered with appressorium formation in germinating conidiospores of Magnaporthe grisea on hydrophobic surfaces. In the absence of a hydrophobic surface, induction of appressorium formation by cAMP, 8,4-chlorophenylthio-adenosine-3′,5′-monophosphate, 3-isobutyl-1-methylxanthine or 1,16-hexadecanediol, a plant wax component, was not affected. When the chemical signals were tested on a hydrophobic surface, however, no formation of infectious structures was observed in the presence of glisoprenin A. The results indicate that in appressorium formation two signal transducing pathways are involved, which operate partly independently of each other.