Salicylates of intact Salix myrsinifolia plantlets do not undergo rapid metabolic turnover.
Salicylates, the main phenolic glucosides of northern willow (Salix spp.), play an important role in plant-herbivore interactions. Salicylates are labile metabolites that are thought to undergo metabolic turnover. Salicylates are synthesized from phenylalanine (Phe) via the shikimate pathway. 2-Aminoindan-2-phosphonic acid (AIP), a strong inhibitor of Phe ammonia-lyase (EC 4.3.1.5), was used to block the biosynthesis of salicylates. The aim of this study was to investigate long-term turnover of salicylates in intact micropropagated plantlets of Salix myrsinifolia Salisb. The biosynthesis of salicylates was inhibited efficiently but not completely by 30 microM 2-aminoindan-2-phosphonic acid. Inhibitor treatment, aside from leading to a high accumulation of Phe, also led to an increase in tyrosine and tryptophan, indicating that 2-aminoindan-2-phosphonic acid may also inhibit enzymes other than Phe ammonia-lyase. Salicylates were shown to be unexpectedly stable metabolites that did not undergo marked metabolic turnover in intact plants; in leaves no significant turnover occurred, and in the stems the five salicylates studied were turned over slowly, with half-lives of 11 to 25 d. The total amount of salicylate in mature shoots decreased only 0.6% per day.
Ruuhola
T M
TM
Department of Biology, University of Joensuu, Box 111, FIN-80101 Joensuu, Finland. ruuhola@cc.joensuu.fi
Julkunen-Tiitto
M R
MR
D000598:Amino Acids, Cyclic / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007189:Indans / Q000494:pharmacology; D007700:Kinetics; D010650:Phenylalanine Ammonia-Lyase / Q000037:antagonists & inhibitors; D018515:Plant Leaves / Q000378:metabolism; D018520:Plant Shoots / Q000378:metabolism; D018547:Plant Stems / Q000378:metabolism; D019685:Rosales / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D012459:Salicylates / Q000378:metabolism*
D000598:Amino Acids, Cyclic; D004791:Enzyme Inhibitors; D007189:Indans; D012459:Salicylates; D010650:Phenylalanine Ammonia-Lyase