This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Web of Science (21) Citing Articles via Google Scholar Google Scholar Articles by Davidonis, G. H. Articles by Mumma, R. O. Search for Related Content PubMed PubMed Citation Articles by Davidonis, G. H. Articles by Mumma, R. O. Agricola Articles by Davidonis, G. H. Articles by Mumma, R. O.

Articles

Metabolism of 2,4-Dichlorophenoxyacetic Acid (2,4-D) in Soybean Root Callus ¹

EVIDENCE FOR THE CONVERSION OF 2,4-D AMINO ACID CONJUGATES TO FREE 2,4-D

Pesticide Research Laboratory and Graduate Study Center, The Pennsylvania State University, University Park, Pennsylvania 16802, Department of Entomology, The Pennsylvania State University, University Park, Pennsylvania 16802, Department of Biology, The Pennsylvania State University, University Park, Pennsylvania 16802

An auxin-requiring soybean root callus metabolized [1-¹⁴C]-2,4-dichlorophenoxyacetic acid (2,4-D) to diethyl ether-soluble amino acid conjugates and water-soluble metabolites. The uptake in tissue varied with incubation time, concentration, and amount of tissue. Uptake was essentially complete (80%) after a 24-hour incubation and the percentage of free 2,4-D in the tissue fell to its lowest point at this time. At later times, the percentage of free 2,4-D increased and the percentage of amino acid conjugates decreased, whereas the percentage of water-soluble metabolites increased only slightly. Similar trends were seen if the tissue was incubated for 24 hours in radioactive 2,4-D, followed by incubation in media without 2,4-D for 24 hours. Inclusion of nonlabeled 2,4-D during the 24-hour chase period did not reduce amino acid conjugate disappearance but did reduce the percentage of free [1-¹⁴C]2,4-D. Thus, an external supply of 2,4-D does not directly prevent amino acid conjugate metabolism in this tissue. It is concluded that 2,4-D amino acid conjugates were actively metabolized by this tissue to free 2,4-D and water-soluble metabolites.