PHOTOINDUCED CONIDIATION IN TRICHODERMA-VIRIDE

Trichoderma viride is a deuteromycete in which conidiation is photo-in ducible. Conidiation results when colonies grow in the day- night regi me or when colonies grown in the dark are exposed to short pulses of n ear UV or blue light. Conidiation was induced by light pulses at inter vals of 8, 16, 24, 48 or 72 hours. Several membrane-damaging agents, D NA-intercalating drugs and inhibitors of RNA or protein synthesis prev ent photo-conidiation, A hypothetical scheme of photo-induced conidiat ion, based on the results with metabolic inhibitors, is presented. A s udden increase of intracellular ATP was observed as an immediate photo -response. The ATP level is dose-dependent, with a maximum at 1.2 klx. Drugs interfering with various signalling pathways were tested in an attempt to analyze the signal pathways whereby light pulses induce con idiation. Non-conidiating and color mutants have been obtained and use d in complementation studied by means of heterokaryosis and protoplast fusion. In a color mutant with brown conidia, conidiation is accompan ied by high production and excretion of anthraquinone metabolites.