Studies on sporopollenin biosynthesis in Cucurbita maxima (DUCH.) - II. The involvement of aliphatic metabolism

Due to the results of spectroscopic analysis, an involvement of aliphatics in the structure of the sporopollenin molecule has been proposed. To test t his assumption on a biochemical level, tracer experiments were carried out in which the aliphatic moiety of the biopolymer was targeted. Tracer experi ments were focussed on the incorporation of C-14-labeled substances, such a s acetic acid, malonic acid, stearic acid, oleic acid and linoleic acid. Se veral cofactors and inhibitors of sterol biosynthesis were used to enhance the incorporation rates of the precursors. The highest incorporation rates were obtained with acetic acid in the presence of a sterol biosynthesis inh ibitor. The incorporation of this precursor could be increased to a signifi cant extent if AMO 1618 was added simultaneously with the tracer. In the ca se of fatty acid the best results were obtained with oleic and stearic acid s. With the significant incorporation of these substances the involvement o f the aliphatic metabolism in biosynthesis of sporopollenin could be verifi ed.