Die Wirkung von hellroter und blauer Strahlung auf die Chloroplastenausbildung

Abstract

Growth and morphogenesis of young fern gametophytes, e.g. of Dryopteris filix-mas, is completely controlled by light. This remarkable light effect has nothing to do with photosynthesis but is a good example of photomorphogenesis, i.e. direct control of growth and development by light. Only short wave visible light (blue) has been found to be photomorphologically effective. Under longer wave visible light (red) the sporelings continue to grow as "etiolated" filaments very similar to those formed in darkness, whereas under blue light normal 2-dimensional growth and prothallium formation can occur. The induction of morphogenesis by blue light is causally connected with an increase of protein synthesis. Sporelings growing in the blue contain much more protein (as related to dry weight) than sporelings growing in the red at about the same photo-synthetic rate. It is here shown that that the size of chloroplasts in cells of these sporelings can be controlled by light. In darkness the chloroplasts are smaller than in red or blue light, but in the blue they become much larger than in the red. The control of plastid size is reversible; for example, if sporelings which have been grown in the red are kept under blue light the chloroplast size increases rapidly up to a certain value, but if they are brought back into the red the original size will be regained within a few days. It was concluded that the protein content of the plastids is controlled by light and that changes of the plastid size are manifestations of a change in protein content of the plastids.