Metabolic fate of 14C-labelled nicotinamide and adenine in germinating propagules of the mangrove Bruguiera gymnorrhiza.
We studied the metabolic fate of [carbonyl-14C]nicotinamide and [8-(14)C]adenine in segments taken from young and developing leaves, stem, hypocotyls, and roots of a shoot-root type emerging propagule of the mangrove plant Bruguiera gymnorrhiza. Thin-layer chromatography was used together with a bioimaging analyser system. During 4 h of incubation, incorporation of radioactivity from [carbonyl-14C]nicotinamide into NAD and trigonelline was found in all parts of the propagules; the highest incorporation rates into NAD and trigonelline were found in newly emerged stem and young leaves, respectively. Radioactivity from [8-(14)C]adenine was distributed mainly in the salvage products (adenine nucleotides and RNA), and incorporation was less in catabolites (allantoin, allantoic acid, and CO2). Adenine salvage activity was higher in young leaves and stem than in hypocotyls and roots. Over a short time, the effect of 500 mM NaCl on nicotinamide and adenine metabolism indicated that NaCl inhibits both salvage and degradation activities in roots.