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EIN BEITRAG ZUR INTERPRETATION DER DUNKELROTBANDE DER HOCHENERGIEREAKTION BEI DER PHOTOMORPHOGENESE (LICHTABHÄNGIGE ANTHOCYANSYNTHESE BEI SENFKEIMLINGEN, SINAPIS ALBA L.)
W. Bertsch and H. Mohr
65. Bd., 3. H. (1965), pp. 245-258
Published by: Springer
Stable URL: http://www.jstor.org/stable/23365422
Page Count: 14
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Anthocyanin synthesis in mustard seedlings is known to be controlled by phytochrome and by a hypothetical "high energy reaction" (Mohr 1957). This "high energy reaction" (= HER) is characterized by an action spectrum with peaks in the far-red and in the blue range of the visible spectrum (Fig. 2). Photosynthesis is not involved (Bertsch and Mohr 1965). The present paper is concerned with the problem of whether at least the far-red action band of the HER could be explained on the basis of phytochrome. It is evident, however, that the action spectrum of the HER elaborated with simultaneous red background irradiation (Fig. 2), the irradiance-response curves (Fig. 3) and the time-response curves (Fig. 4) are hardly to be explained on the basis of the presently accepted phytochrome theory (e. g. Hendricks 1964). Red light is only slightly effective in anthocyanin synthesis of mustard seedlings when brief exposures to red are used in order to once saturate the photostationary state of phytochrome (Fig. 5). If, however, brief exposures to red are preceded by long exposures to far-red, the red is much more effective (Fig. 6). Long exposures to far-red increase the sensitivity of the system to red (Table 1). — On the other hand, a pretreatment with long exposures to red will decrease considerably the sensitivity of the system to far-red (Fig. 7, Table 1). These data, too, cannot be understood solely on the basis of the conventional phytochrome theory. It is assumed, following a recent hypothesis by Hartmann (1965) for hypocotyl lengthening in lettuce seedlings (Table 2), that at least the far-red band of action of the HER can eventually be understood on the basis of phytochrome if the in-vivo destruction of phytochrome 730 (Butler 1964) is taken into account. This assumption is supported by recent experiments in which anthocyanin synthesis in the mustard seedling was studied under steady state conditions of irradiation (Mohr, Wagner and Hartmann 1965), but more data and more reasoning will be required before the explanation of the HER on the basis of phytochrome will be satisfactorily established.
Planta © 1965 Springer