The amino acid metabolism of Dichapetalum cymosum (Gifblaar)

Summary The metabolism of NMA-methyl-14C and NMA-alanine-14C in young and old leaves of Gifblaar was compared to that of methionine-methyl-14C and alanine-14C. Less than 1% of the label was found in the organic acid and sugar fraction whereas 5–10% of the label appeared in the lipid fraction. The label pattern observed with all precursors was consistent with the active functioning of the Krebs cycle in young but not in old leaves. The most important part of the metabolism of NMA was that it acted as a methyl donor in the biosynthesis of N-methyl-L-serine from serine in both old and young leaves. The label pattern of NMA-alanine-14C and alanine-14C differed to such an extent that it was clear that this was not the only pathway involved in the metabolism of NMA. An explanation is also offered for the good correlation found between NMA content and fluoroacetate content in various parts of the plant.