An Action Spectrum for Light Induced Sporulation in the Fungus Ascochyta pisi.

Though light induced reproduction, both sexual an(l asexual, is common to many fungi (15), the mlechanisnm ;of this phenomenon is not un(lerstood. Suggestions have been made on the possible nature of a photoreceptor pigment involved (5) but there has been little experimental evidence to support or refute these views. Recent studies with .4scochyta pisi, Lib. (9), Pleospora herbarunm (Pers.) Rabenh. (11) and Alternaria chrysanthemi Schmidt (12) have lea(l to the postulation that photo-induced asexual reproduction in a number of fungi involves the samiie chemical mechaniislmi, andl that radiant energy is captured by a receptor pigment which absorbs ultraviolet radiation imiost effectively (12). The objective of this present studY was to deternmine the action spectrum for light in(luce(d sporulation of Ascochyta pisi in the lhope that this might provide clues to the nature of the photoreceptor pigment involved. There are no reports of actioIn spectra for light induced sporulation in fungi belonging to the Ascomycetes, the Basidionmycetes, or the Deuteromycetes. Page (16) (letermine(l the action spectrum for trophocyst formation in the Phycomycete Pilobolus and reported that the effective wavelengths are from 380 to 510 my. He believes that light absorption by a flavin probably initiates the formation of trophocysts. Wavelengths from 380 to 510 m,u have been ineffective in stimulating sporulation in the Ascomycetes and Deuteromycetes studied intensively in this laboratory (9, 11, 12). Aragaki (2) an(I Lukens (14) have published action spectra for photo-inhibition of sporulation in species of Alter-