ULTRAVIOLET-ABSORBING SUBSTANCES ASSOCIATED WITH LIGHT-INDUCED SPORULATION IN FUNGI

Publisher Website
Google Scholar
Abstract
An unidentified substance(s), proyisonally named P310, is produced in mycelia of Alternaria chrysanthemi, Ascochyta pisi, Ophiobolus graminis, Pleospora herbarum, and Pyronema omphalodes when sporulation has been induced with near-ultraviolet radiation. This same substance is absent in non-sporulating colonies grown in darkness. It is, however, present in unexposed colonies of A. pisi grown on media which are able to support sporulation in the absence of light. P310 is extractable with cold absolute ethanol, is water-soluble, passes through a dialysis membrane, is retained on a cation exchange resin, and appears to be composed of at least four possibly related substances. Maximum absorption of P310 is between 260 and 340 m[mu] is lost. P310 can be detected spectrophotometrically in extracts of colonies exposed to 6 hours of near-ultraviolet radiation, but not after a 1 hour exposure. Conidiospores of A. pisi contain P310. which may be a "sporulating factor" associated with these spores. The rate of P310 production in irradiated colonies appears to be related to length of exposure, yet this substance can be produced in darkness for a limited period following stimulation of colonies by near-ultraviolet radiation. Neither the identity nor the modus operandi of P310 has yet been demonstrated.