Perithecial formation in Gelasinospora reticulispora : VI. Inductive Effect of Microbeam Irradiation with Blue Light.

When hyphae in the basal region of 72-hold, dark-grown mycelium of G. reticulispora (Greis et Greis-Dengler) C. et M. Moreau (Sordariaceae) were exposed to a microbeam of monochromatic blue light, perithecial initials were induced only in hyphae located within or in the vicinity of the light spot. The average distance from the periphery of the microbeam spot to perithecial initials produced outside the spots was 100-200 μm, regardless of the beam diameter or the incident light energy. The maximum distance of a perithecium formed outside a microbeam spot was ca. 700 μm. The inductive effect of blue light became detectable at 100 J m(-2) and reached a maximum at 1000 J m(-2), regardless of beam diameter. A microphotographic examination showed that the microbeam irradiation was effective only in hyphae rich in protoplasm.