Some effects of 2,4-dichlorophenoxyacetic acid on soluble nucleotides & nucleic acid of soybean seedlings

One of the most marked biochemical changes in plants known to accompany 2,4-D4 treatments is the increase in nucleic acid. Rebstock et al (33) found the nucleic acid content to double in the stems of bean plants after 2,4-D treatment. Similar increases in the RNA content of 2,4-D-treated cucumber plants were reported by West et al (40) ; 2,4-D treatment was also shown to alter the RNA content of excised tissue both in cucumber and in corn (40). It has been proposed that auxin action is linked to nucleic acid metabolism (36), and that an alteration of nucleic acid metabolism is involved in the abnormal growth and development of 2,4-D-treated plants (33). Work by Marre and Forti (24) has shown that auxins initiate a large increase in ATP in pea stem sections within 30 minutes after treatment. More recently Ormrod and Williams (29) have shown that 2,4-D treatment causes a rapid rise in soluble organic phosphates, suggesting an increase in such compounds as ATP (since inorganic phosphate is usually incorporated into organic compounds via oxidative phosphorylation). RNA is apparently involved in such processes as protein synthesis (3), oxidative phosphorylation (12), and ion absorption (19,38), processes known to be affected by 2,4-D (9, 16, 28, 35, & 37). Soluble nucleotides are involved in such essential biological processes as oxidative phosphorylation (20), amino acid metabolism (8), carbohydrate transformations ( 14), and lipide syntheses ( 1 5). Therefore it seemed that additional basic information on the effects of 2,4-D on nucleotide metabolism was needed. These data are results of experiments undertaken to study some relationships of 2,4-D to nucleotide metabolism. The results suggest that changes in nucleotide metabolism may underlie the growth aberrations induced by 2,4-D. However, more basic knowledge of the normal growth processes will be necessary before the role of 2,4-D as an auxin or as a herbicide can be fully clarified.