Die Beziehungen zwischen Lipochinonsynthese und Plastoglobulibildung in den Chloroplasten von Ficus elastica Roxb. / The Correlation between Lipoquinone Accumulation and Plastiglobuli Formation in the Chloroplasts of Ficus elastica Roxb.
The structure of plastids, as well as size and frequency of the osmiophilic plastoglobuli were studied from the development of Ficus leaves until the degeneration of older leaves and compared with the accumulation of excess plastid-quinones. 1. The plastids on the young, light green Ficus leaves still rolled up in the buds already contain thylakoids. Prolamellar bodies and small plastoglobuli are, however, still present. Few days after leaf-unfolding the prolamellar bodies are used up in thylakoid formation; the number of plastoglobuli is reduced concurrently. 2. Thereafter size and frequency of the osmiophilic plastoglobuli increase with the age of Ficus chloroplasts. In several-year-old green Ficus leaves large plastoglobuli up to 3,5 μ diameter with the greatest frequency at 0,5 μ diameter can be found. During chloroplast degeneration in senescent leaves both thylakoids and plastidstroma are dissolved progressively. The plastoglobuli remain. Their size still increases during chlorophyll breakdown. In the final yellow tob rown stage of Ficus leaves the plastids predominantly contain some larger plastoglobuli up to 7 μ arising by fusion of smaller ones. 3. The accumulation of excess plastidquinones - mainly α-tocopherol and plastohydroquinone 45 - proceeds concurrently to the formation and enlargement of the plastoglobuli. It is shown that the excess plastidquinones of Ficus chloroplasts are deposited in the osmiophilic plastoglobuli whose size thus increases. The isolated plastoglobuli predominantly contain α-tocopherol and plastohydroquinone 45, in lower concentrations also plastoquinone 45, α-tocoquinone, and vitamin K1, traces of carotenoids, but no chlorophylls. 4. During chlorophyll and thylakoid breakdown those lamellar lipids (carotenoids, plastidquinones) not decomposed are deposited together with the newly formed plastidquinones in the osmiophilic plastoglobuli. Plastoglobuli of degenerating chloroplasts thus contain more carotenoids than plastoglobuli from fully functional chloroplasts of green Ficus leaves.