APPEARANCE OF PHOTO-CHEMICAL FUNCTION IN PROTHYLAKOIDS DURING PLASTID DEVELOPMENT

1. A method to separate the vesicles of prothylakoids from prolamellar body preparations obtained from etiolated and rapidly greening Avena laminae (0.25-4 h illumination) is described. The prothylakoid preparations were found to be free from contaminating prolamellar bodies but enriched prolamellar body preparations (enriched prolamellar body preparations) still contained some adhering prothylakoid material. 2. Only existing β-carotene appears to be transferred from the prolamellar bodies to the prothylakoids during early development and this ceases when freshly synthesized β-carotene becomes available. 3. Prolamellar body structures proper show no positive association of existing or developing photochemical activities; these are only to be found in the developing prothylakoids. 4. Using methylviologen-linked electron transport-dependent oxygen consumption, Photosystem I activities may be detected with added diaminodurene within 15 min of illumination and within 30 min and 1 h with added tetramethylphenylenediamine and dichlorophenolindophenol, respectively. 5. During the 2nd. and 3rd. h of greening, proton-pumping capability and later ATP formation increased in prothylakoids in the presence of diaminodurene. 6. The first indications of Photosystem II activity using diphenylcarbazide as electron donor are shown at a similar time (2 h) with prothylakoids. The last photochemical activity to appear is the capacity to split water (3 h) and consequently the diphenylcarbazide activity diminishes to zero before 8 h of illumination have passed. 7. The lack of effect of uncouplers such as NH+ 4 prior to 2 h suggests that in spite of some proton-pumping ability there is the possibility of proton-leaky areas existing within prothylakoids. This. lack of a persistent proton gradient before 2 h of illumination may explain the different starting times of phenazine methosulfate- and diaminodurene-dependent photophosphorylation (0.25 and 2 h, respectively). © 1979.