Effect of 2,4-Dichlorophenoxyacetic Acid on the Nucleic Acid and Protein Content of Seedling Tissue

Abstract

NE of the most marked effects of herbicidal concentrations of '2,4-D (2,4-dichlorophenoxyacetic acid) is the swelling and proliferation of basal stem tissues. Sell et al. (15) reported a large increase in the protein content of stems of bean plants treated with 2,4-D. Shaw, et al. (16) observed an increase of total protein in plants treated with 2,4-D and Rebstock, et al. (14) found the nucleic acid content to double in the stems of bean plants treated with 2,4-D. Rebstock et al. postulated that nucleic acid was involved in the unusual growth and development of the plant. Skoog (17) has presented an attractive hypothesis linking auxin action with nucleic acid metabolism. Current biochemical investigations leave little doubt that RNA (ribonucleic acid), particularly of the microsome fraction of the cytoplasm, is involved in protein synthesis (1). Furthermore, RNA appears to be implicated in oxidative phosphorylation (6) and ion absorption (8, 21), two processes known to be affected by 2,4-D (4, 12, 20). The experiments reported here are the initial results of a study to determine if the herbicidal effects of 2,4-D are linked to aberrations in nucleotide metabolism. The results suggest that this may be true, but additional basic knowledge of the biochemistry of nucleotide metabolism in growing cells will be required if the question is to be fully answered.