Studies in Plant Metabolism. III. Absorption, Translocation and Metabolism of Radioactive 2,4-D in Corn and Wheat Plants.

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Abstract
A sample of carboxyl-C14-labeled 2,4-D with a specific activity of 5.3 x 106 cpm/mg was synthesized and used in these experiments. A study has been made of the absorption and translocation of radio-active 2,4-D by the corn and wheat plants. The results indicated that this growth regulator is absorbed by the monocots, but at a slower rate than that found in bean plants. The translocation of C14 to the apical portion of the corn and wheat plants was very slow. There seems to be a block in the intercalary meristem of the monocotyledonous stems and leaves of young plants. A part of the applied 2,4-D is incorporated in a few days into other compounds. Two major compounds, which were designated as un- known 1 and unknown 3, were found in the 80% alcohol extracts of leaves from both 2,4-D treated corn and wheat plants. The latter unknown which was found in a greater concentration, indicated a difference in metabolism of 2,4-D in corn and wheat plants from that found in the bean plants. The identity of the major unknown radioactive compounds has not been established. However, the complexity of the molecule of these two 2,4-D conjugates has been demonstrated.