Stimulation of Armillaria ostoyae vegetative growth by tryptophol and rhizomorph produced by Zygorhynchus moelleri

Tryptophol (an indole-3-ethanol analogue which is a major secondary metabolite produced by Zygorhynchus moelleri) stimulated the growth of 13 out of 18 isolates of Armillaria ostoyae in culture. Rhizomorph production of 16 out of 18 isolates of A. ostoyae was enhanced by the presence of Z moelleri in oak branch segments. Tryptophol can be considered as a growth-promoting substance stimulating the vegetative growth of A. ostoyae in culture, and Z. moelleri as a fungus stimulating the rhizomorph formation on oak wood.