Inhibition of signal transduction leading to appressorium formation in Magnaporthe grisea by glisoprenins

摘要

From submerged cultures of the deuteromycete Gliocladium roseum, strain HA190-95, glisoprenins A, C, D and E were isolated as inhibitors of appressorium formation in Magnaporthe grisea. The compounds inhibited formation of infection structures on hydrophobic, stimulating surfaces. Glisoprenin E was ten times less active compared to the other glisoprenins. Formation of appressoria on nonstimulating surfaces, induced by the cAMP analogue 8-(4-chloro-phenylthio)-adenosine-3',5'-monophosphate or by 1,16-hexadecanediol, a plant wax component, was not affected by glisoprenins, indicating that at least two signal transduction pathways are involved in appressorium formation in M. grisea. Inhibition of appressorium development by glisoprenins on hydrophobic surface could be reversed in a competitive manner by 1,2-dioctanoylglycerol, a known activator of protein kinase C (PKC) but not by 1-oleoyl-2-acetylglycerol, the most effective inducer of PKC in mammalian cells.