Struktur und Funktion der genetischen Information in Piastiden XV. Beziehungen zwischen Chlorophyllgehalt, Photosyntheseverhalten und Piastidenfeinstruktur in Kerngen-bedingten Aureamutanten von Antirrhinum majus (Mutante „Aurea“) und Pelargonium zonale (Sorte „Cloth of Gold“)

Abstract

Summary The electron microscopic observations of yellow-green and green plastids of Antirrhinum and Pelargonium demonstrate direct connections between fine structure, chlorophyll content and photo-synthetic activity. It can be shown that in young yellow-green plastids a significant decreased level of chlorophyll b is correlated with a very low amount of stacked thylakoids. A normalization of the chlorophyll a/b-ratio in the course of the development and increased greening of the plastids is connected with a preferential building of partitions. This finding supports the conception of a direct participation of chlorophyll b in the formation and maintenance of grana stacks. Young Aurea plastids accumulate only a small amount of chlorophyll, but they are photosynthetically active. Plastom mutants of the same species have an impaired photosynthesis in spite of a higher chlorophyll content (Herrmann 1971; Herrmann and Hagemann 1971). Besides of magnograna only perforated primary thylakoids are present in the mutant plastids (Knoth 1975). The Aurea plastids, however, posses always continous stromal membranes. This structurally detectable difference between both kinds of plastids is based probably on lacking or presence of chlorophyll-proteincomplex I and possibly represents the cause for a blocked or intact photosynthesis.