Die Lokalisation der Plastidenchinone und Carotinoide in den Chromoplasten der Petalen von Sarothamnus scoparius (L.) Wimm ex Koch

Abstract

The yellow petals of Sarothamnus are colored by chromoplasts which contain free xanthophylls and carotenoid esters. During development of chromoplasts from young chloroplasts the secondary carotenoids are formed together with plastidquinones of the benzoquinone-type (mainly α-tocopherol). The formation of secondary carotenoids already starts in the green petals of the buds. Their main synthesis however, proceeds parallel with a partial destruction of chlorophyll and thylakoids. The secondary carotenoids are accumulated predominantly in the plastids of the epidermal and subepidermal cells. Concurrently the number of plastoglobuli is strongly increased. The isolated plastoglobuli show the same size distribution (40–200 nm) as in situ on the electromicrograms. They contain both lipid classes, carotenoids and plastidquinones. Most of the carotenoid-rich Sarothamnus-plastoglobuli are much less electron dense than the plastoglobuli of green leaf tissue, which contain only traces of carotenoids. The general function of plastoglobuli in chromoplasts as stores for carotenoids and plastidquinones is discussed.