Effect of light on the formation of atypical fruiting structures in Ganoderma lucidum

Abstract

Ganoderma lucidum develops atypical fruiting structures (AFSs) with non-basidiocarpous basidiospores during the incubation under light on nutrient agar media. To examine the light quality effective in inducing AFSs, 17 isolates ofG. lucidum were incubated on agar media under light from different colored fluorescent lamps. Of the 17 isolates, 13 isolates produced AFSs and basidiospores under fluorescent lamps. Nine isolates formed AFSs in a broad light region from P-B (pure blue) to P-R (pure red) lamps. The remaining 4 isolates produced AFSs under different colored fluorescent lamps. No isolates formed AFSs in the dark or under BLB (black light blue) illumination. The mycelial growth was inhibited by light illumination, especially BLB light. Although the AFSs were induced at a very low light intensity such as 0.5µmol m−2s−1, the optimum light intensity for the AFS formation varied depending on the kind of fluorescent lamp and the isolate. The AFS formation inG. lucidum isolates was also tested under monochromatic light produced by the combination of interference filters and colored glass filters.G. lucidum isolates were separable into various types in the responses of AFS formation to monochromatic light, indicating thatG. lucidum is heterogeneous in its photo-response with regard to AFS formation.