Biochemie und Physiologie der Pflanzen
Summary 1. The amount of allantoin and allantoate was determined in moss callus grown under various light conditions. It can reach 26,5 % of the plant nitrogen content. The accumulation is influenced by light intensity and colour. 2. Red-light (660 nm) causes a greater allantoin level in the cells than blue light and white light illumination. Red-light favours the formation of young setae from the moss callus. We could detect a relation between the intensity of seta-development and the amount of allantoin. The accumulation is increasing with the growth of the setae. 3. Blue-light (440 nm) enhances the chlorophyll synthesis and promotes chloroplast develop ment. This effect is correlated with a high degrading-activity of allantoin by the plant extracts. Callus grown in the dark shows a low enzymatic activity and a much greater allantoin accumulation than the illuminated cultures. We suggest that there may be some connection between allantoin metabolism, chloroplast development and photosynthesis. 4. The main part of the observed amount of allantoin (shown with 14 C-Adenin) comes from the degradation of purin bases and nucleic acids. 5. The moss callus showing marked heterotrophic tendences has only little degradingcapacity for allantoin. The gametophytes regenerated from the callus can use allantoin as a nitrogen source. This products of regeneration seem to be more autotrophic.