The formation of chlorophyⅡ-protein complexes (CP-complexes) during the greening of rape cotyledons (Brassica napus cv. Yongdang) was investigated by the SDS-poly-acrylamide gel electrophoresis. The total chlorophyⅡ content and ChⅠ a/b ratio were also determined. In addition, the effects of dark treatment on the CP-complex patterns during greening have been examined with respect to their photosynthetic electron transport activity. Greening has brought about the increase in total chlotophyⅡ content and the decrease in ChⅠ a/b ratio, but there have been no changes in ChⅠ a/b ratio after 24 hrs of greening. The light-harvesting chlorophyⅡ a/b-protein complex (LHCP-complex) was predominant during the initial greening period. Thereafter, the amount of chlorophyⅡ a-protein complex (CP Ⅰ-complex) was gradually increased. Twenty-four-hr dark treatment immediately after illumination for 6 hrs and 12 hrs resulted in the increase of the ChⅠ a/b ratio and the CP Ⅰ complex, otherwise the decrease of the LHCP-complex.
The LHCP/CP Ⅰ ratio was gradually decreased with further greening, and appeared no change after 48 hrs illumination. The investigation of the photosynthetic electron transport activity indicated that photosystem (PS) Ⅱ activity (H_2O→p-PD^*＋FeCy^**) did not change, but the activity of PS Ⅰ was increased suddenly due to the dark treatment. The data suggests that the increase of CP Ⅰ-complex may result in that of P-700, that is, the increase of PS Ⅰ activity.
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