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-1-C-13 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 C-13 or H-2 were isolated from root-washings of the same plants. The C-13-NMR elucidated that three molecules of L-methionine were incorporated into avenic acid A in the same way as 2'-deoxymugineic acid. The H-2-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.