[A specific effect of blue light on the incorporation of photosynthetically assimilated (14)C into the protein of fern sporelings [dryopteris filix-mas (L.) Schott]].

Morphogenesis and metabolism of the early gametophytes (=sporelings) of the common male fern are controlled by light. The "normal" two-dimensional development of the gametophytes takes place only in white or blue light; in red light alone, on the other hand, the sporelings remain filamentous even under conditions of equal photosynthetic rate.The problem has been whether blue light exerts its morphogenic influence through differential gene activation. In other words: does blue light mediate the synthesis of "morphogenic enzymes" which are required for "normal" morphogenesis. In an earlier paper (DRUMM and MOHR, 1967) we have shown that blue light increases the rate of RNA synthesis within an hour whereas the first indication of a morphogenic change due to blue light is only discernible about 3 hours after the onset of blue light (Figs. 1,2). Furthermore we have shown (MOHR, 1965) that Actinomycin D specifically inhibits the blue light mediated morphogenic alterations, and BERGFELD (1967) has shown that blue light will rapidly lead to changes in nuclei and nucleoli in the fern sporelings. In the present paper it has been shown that blue light does increase the rate of protein synthesis about an hour after the transfer of the sporelings from the red into the blue light of equal quantum flux density (350 pE·cm(-2)·s(-1)).The rate of protein synthesis was measured in shortterm experiments (40min) using (14)CO2. The photosynthetic rate was the same in red and blue; it was not influenced by the transfer(Fig. 3). Likewise the rate of (14)C incorporation into the pool of free amino acids was not significantly different in red and blue light (Fig.4). On the other hand, the rate of incorporation of (14)C into the protein increased rapidly after the transfer of the sporelings from the red into the blue light (Fig. 5). The same phenomenon (no influence of blue light on the specific activity of the free amino acid; a strong promotive influence on the specific activity of the protein-bound amino acid) was observed in the case of alanine which was investigated in detail (Figs. 6, 7). Since the increase of the protein content of the sporelings is not significant during the first six hours after transfer to blue light (Fig. 8) the protein induced by blue light and directly related to morphogenesis can only be a very small fraction of the total protein of the sporeling.The data strongly support the hypothesis (OHLENROTH and MOHR, 1964), that the morphogenic effect of blue light on the fern sporelings is due to the induction of "morphogenic enzymes" by blue light.