Enhancement by Auxin of Ribonucleic Acid Synthesis in Excised Soybean Hypocotyl Tissue

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Abstract
Growth promotive concentrations of auxin enhanced Cl4-nucleotide incorporation into RNA of the elongating zone of the soybean hypocotyl, whereas growth inhibitory concentrations decreased incorporation. In fully elongated cells, auxin induced a 25 to 30% net increase in RNA. This enhanced synthesis of RNA occurred at a linear rate for at least 9 hours after an initial lag. Results from time course experiments on C14 nucleotide incorporation into RNA, in conjunction with differential centrifugation of tissue homogenates, indicate that a net transfer of Cl4 rnA from the nucleus to the ribosomes occurred. The synthesis of RNA was inhibited by 85-90% by actinomycin D. From the known action of actinomycin D, most (if not all) of the RNA in soybean hypocotyl cells must be synthesized on a DNA template.