Effects of 2,4-D on Metabolism of 14C-Glucose in Plant Tissues

A time course study on the in vitro effect of 10 –4 M (2,4-dichlorophenoxy)acetic acid (2,4-D) on the metabolism and incorporation of specific 14 C-labeled glucose into pea ( Pisum sativum L., var. Alaska) and corn ( Zea mays L., var. Golden Cross) tissues showed a preferential release of C-1 as CO 2 which was affected by 2,4-D. The glucuronic acid pathway was stimulated greatly in pea roots and slightly in corn stems; it was inhibited in corn roots. The pentose phosphate pathway was affected in an opposite pattern. The incorporation of both labeled carbon atoms into alcohol-insoluble residue was also affected by 2,4-D. The degree of effect, however, varied from pea to corn and from roots to stems. Analysis of the alcohol-soluble fraction revealed different effects of 2,4-D on labeling of some of the amino acids, an increase in fructose content, and an accumulation of malic acid.