Comparison between the preservation of chloroplast structure in the dark and the turnover rate of chlorophyll-protein complexes in a moss and two varieties of pea

The senescence and preservation of the structure of the chloroplastin the dark was studied in the protonema of Ceratodon purpureusand in two varieties of pea, a tall variety "Dippe Maj" anda dwarf variety "Early low". The latter variety is better ableto survive in darkness, probably because of the larger amountof starch in its chloroplasts. The integrity of the chloroplastswas better preserved in the moss than in the peas. During isolationof the chlorophyll-protein complexes, there was no decreasein the specific activity of the total lamellar extract in anyof the dark-grown materials. This contrasts with the turnoverof chlorophyll-protein complex (CP) II in the dark-grown moss.In the light, CP II had a half life of two weeks in both themoss and the higher plants, whereas no turnover was evidentin CP I. The lack of turnover for CP I is connected with itsdecrease in senescence. ¹Present address: Department of Botany, University of Turku,20500 Turku 50, Finland. (Received July 13, 1979; )