THE PHENOLIC ACIDS IN WHEAT: I. CHANGES DURING GROWTH AND DEVELOPMENT

Abstract

Quantitative determinations were made of p-coumaric, ferulic, caffeic, sinapic, p-hydroxybenzoic, vanillic, and syringic acids which occur as alkali- and acid-hydrolyzable derivatives in ethanolic extracts of wheat tissues. The ethanol-insoluble (cell wall) residues also yielded phenolic acids on cold alkaline hydrolysis. Comparatively large quantities of p-coumaric and ferulic acids (1.8 mg/g dry wt, and 4 mg/g dry wt., respectively, in 25-day-old shoots) were obtained from this fraction, the amounts depending on the age of the tissue. Phenolic acids in the ethanol-soluble fraction reached a maximum concentration about 9 days after germination. The amounts fell off with increasing age, reaching a minimum 4 to 5 weeks later. There was no obvious relationship between the amounts of these acids as reported here and rates of lignification as reported for the wheat plant by others. The behavior of sinapic acid was markedly different from that of p-coumaric and ferulic acids and it is suggested that it may not be a natural precursor of the syringyl units of lignin.