Action Spectrum of Photoinduced Conidiation in Altenaria cichorii

Summary: An action spectrum for photoinduced conidiophore formation in the fungus Alternaia cichorii was determined by exposing colonies to monochromatic radiation obtained from a diffraction grating monochromator. The action spectrum showed a peak near 290 nm with a noticeable shoulder between 310 and 330 nm and another one between 260 and 265 nm. This action spectrum has many common characters with those for photoinduced conidiophore formation of Helminthosporium oryzae and Alternaria tomato, where the induction of conidiophore formation is controlled by a blue-light-inducible, near-UV-reversible, photoreaction.