Biosynthesis of avenic acid a, a ferric chelating substance secreted from avena sativa l

The biosynthesis of avenic acid A was studied by feeding L-methionine-l-13C or D,L-methionine-3, 3, 4, 4-d4 to iron-deficient oat roots (Avena sativa L. cv Amuri II). Both avenic acid A and 2’-deoxymugineic acid labeled with ¹³C or ²H were isolated from root-washings of the same plants. The 13C-NMR elucidated that three molecules of L-methionine were incorporated into avenic acid A in the same way as 2’-deoxymugineic acid. The 2H-NMR spectra indicated that all deuteriums from the methionine were incorporated into 2’-deoxymugineic acid, but one of the deuteriums at C-4 was lost in avenic acid A. A possible biosynthetic pathway is L-methionine-> — 2’-deoxymugineic acid-»avenic acid A.