Perithecial Formation inGelasinospora reticulisporaVII: Action Spectra in UV Region for the Photoinduction and the Photoinhibition of Photoinductive Effect Brought by Blue Light

摘要

An action spectrum for photoinduction of perithecial formation after a prior 72 h dark growth period was determined in the UV region with apically growing mycelia of a sordariaceous fungus,Gelasinospora reticulispora. The spectrum exhibited a peak at 280 nm. Quantum effectiveness of 280 nm irradiation was ca. 1.7 times higher than that of 450 nm light. The number of perithecia induced by UV radiation was saturated at a lower level as compared with blue light. UV radiation having a fluence greater than the saturation level decreased the number of induced perithecia. UV radiation that was given after a saturating exposure to inductive blue light inhibited the inductive effect of blue light. An action spectrum for this inhibition exhibited a peak between 260 and 270 nm. Monochromatic light beyond 350 nm had no inhibitory effect. Inhibitory effects of UV radiation given after inductive blue light irradiation were observed in the fluence range where photoinductive effects of UV radiation became obvious. Therefore, the true height of the UV peak in the photoinduction actionspectrum, when free of distortion from the inhibitory effect, should be higher than the peak obtained in this study.