Partial characterisation of the fruiting inducing factor from the polyporePhellinus contiguus

Filtrates from cultures of wild isolates of Phellinus contiguus grown on li quid medium containing malt extract induced precocious fruiting of this res upinate polypore when tested in a bioassay. Active filtrates were analysed using gel filtration, HPLC and GC-MS and were compared with filtrates from single spore progeny, two of which lacked fruiting inducing activity. The a ctive material was polar and heat stable, passed through both anion and cat ion exchange columns and had a mel, wt less than approx. 1000. Fractionatio n using HPLC on amino-silica yielded one fraction which was active on its o wn and a second, later eluting fraction, which had scarcely detectable acti vity when alone, but when combined with the first fraction had much higher activity than either alone. GC-MS showed that both this first fraction and the most active fraction from P2 gel filtration were rich in mono- and disa ccharide sugars. In comparison with fractions from parallel inactive filtra tes, all active fractions contained more myo-inositol and a relatively high glucose/disaccharide ratio. It is suggested that a combination of high concentrations of myo-inositol a nd apoplastic glucose may be required for initiation of fruiting in P. cont iguus. Although additional work is needed, this view is consistent with kno wn features of growth and fruiting in white rot fungi.