Photosynthese und Photomorphogenese bei Farnvorkeimen vonDryopteris filix-mas

Summary

Under conditions of identical rate of photosynthesis (measured by dry weight increase under steady state conditions) growth and differentiation of the gametophytes of ferns (e.g.Dryopteris filix-mas) are completely different in red and blue light. In the blue light “normal” growth and morphogenesis take place and “normal” two or three-dimensional prothallia are formed (Fig. 3). In the red, however, the prothallia look very similar to those growing in complete darkness: they grow as one-dimensional filaments (Fig. 1).

It has been shown in this paper that photosynthesis, which is important as a source of organic material and free energy, has no influence at all on morphogenesis. Morphogenesis, i.e. the formation of “normal” prothallia instead of filaments, is controlled by a photoreactive system which depends on “blue” light of suitable intensity and which is not related to photosynthesis as such. If no blue light is present no morphogenesis occurs in spite of high photosynthetic activity.

In our opinion theprimary products of photosynthesis are the same in all wavelengths. But now the photomorphogenic light reaction which depends on blue light apparently directs the flow of metabolites. In this way even the same initial products of CO₂ fixation may lead subsequently to rather different photosynthetic products and consequently to the very great difference between prothallia growing with or without blue light.

The addition of sucrose has practically no influence on growth and morphogenesis under our conditions. On the basis of our results we cannot agree with the general conclusions drawn byMiller andMiller (1961) who regard photosynthesis as a “photomorphogenetic system” in these gametophytes of ferns.