Action spectra for photoinhibition of sexual development in Phycomyces blakesleeanus

The sexual development of the fungus Phycomyces is inhibited by light. The action spectra for this photoinhibitory effect were determined for 48 h continuous exposure between 350 and 700 nm wavelengths during the mating process. Effective wavelengths were shorter than 490 nm, but the most effective wavelengths depended on the stage of sexual development. In early stages of progametangium formation, the major peaks appeared near 360 nm with small shoulders at 410nm, but in later stages, after gametangium formation, only single peaks were detected in the UVA range (350-390 nm). Low-fluence irradiation in the later stage, however, revealed inhibitory effectiveness at 370-410 nm, implying the existence of a dual photoresponse and multiple regulatory systems in the mating process of Phycomyces. (author)