Pea (Písum sativum L.) leaves fully developed under either high or low irradiance were exposed for up to 30 h to dark oř limiting, saturating oř excessive iřřadiance. The time courses of degradation of a popidation of radioactively prelabelled Dl protein and the fluorescence parameter Fv/Fm, measured on intact leatf discs at room temperature were studied. The Dl protein degradation was shown to be dependent on irradiance but not directly correlated with changes in photosynthetic capacity. The irradiance dependence of Dl protein degradation was different in the two types of leaves and it occurred at a slow but significant rate in the daik. The irradiance dependence of Dl degradation tnay be associated with the 3-dimensional structure of the thylakoid membrane and is suggested to play a key role in flie regulation of radiant energy absorption and photosynthetic capacity of flie leaves.
Pea (Pisum sativum) leaves grown under high and low iiradiances were exposed for 6 h to a limiting, saturating oř excessive irradiance. The tůně courses of synthesis of the photosystem 2 (PS 2) core proteins D2 and CP43 and CP47 were studied. The D2 protein synthesis characteristics were shown to be dependent on both the growth irradiance and the irradiance during synthesis, reflecáng long-term and short-term adjustments of the plant. CP43 and CP47 synthesis was less susceptible to alterations in irradiance.