Changes in oxo acid concentrations during the growth of groundnut seedlings.

In recent years we have been investigating the occurrence, distribution and metabolism of unsaturated amino acids in groundnut plants (Arachi8 hypogaea). Three related amino acids have been identified, namely (i) y-methyleneglutamic acid (y-MGA), (ii) its amide, y-methyleneglutamine (y-MG), and (iii) its decarboxylation product, y-amino-a-methylenebutyric acid (Done & Fowden, 1952; Fowden & Done, 1953). These substances are not ubiquitous in plant species, and have so far only been reported in tulips (Zacharius, Pollard & Steward, 1954), hops (Tatchell & Harris, 1953), and in a Lilium sp. (personal communication from Dr G. H. N. Towers, Montreal). A possible pathway for the biological synthesis of y-MGA could involve its oxo acid analogue, ymethylene-a-oxoglutaric acid (y-MOG), as an intermediate stage (Fowden, 1954). Some support for this idea has resulted from the isolation of this oxo acid (as the 2:4-dinitrophenylhydrazine derivative) from tulips (Towers & Steward, 1954), and groundnuts (Fowden & Webb, 1955). Investigations reporting the oxo acid concentration levels in higher plants have been few in number, and although Virtanen, Miettinen & Kunttu (1953), and Towers, Thompson & Steward (1954) have determined the concentrations of the main acids of some plant tissues, we believe that this is the first publication which relates the oxo acid levels in different plant organs to the stage of development of the plants. The quantitative distribution ofy-MOG and other oxo acids found in groundnut plants at different stages of their early seedling growth is reported. Since a similar study of the distribution ofy-MGA and y-MG has already been made (Fowden, 1954), a comparison of the importance of the related types of y-methylene compounds during seedling development can now be made.