Greater Length of Ribonucleic Acid Synthesized by Chromatin-bound Polymerase from Auxin-treated Soybean Hypocotyls

An investigation has been made of the RNA synthesized by chromatin-bound RNA polymerase from soybean hypocotyls (Glycine max var. Wayne). Polymerase activity is 4- to 5-fold higher with chromatin from tissue treated with 2,4-dichlorophenoxyacetic acid, a synthetic auxin, compared to untreated tissue. Thin layer chromatography of the RNA hydrolysis products and acrylamide gel electrophoresis of the RNA synthesized by the chromatin show that increased activity induced by 2,4-dichlorophenoxyacetic acid is due primarily to the production of longer RNA chains, with only 20 to 50% increase in the number of RNA chains. The observation that 2,4-dichlorophenoxyacetic acid treatment leads to greater rates of RNA synthesis, producing longer chains in unit time, suggests that one manifestation of auxin activity is in activation of RNA polymerase I (ribosomal RNA polymerase).