Stimulation of the Uptake of Water and Ions by lndolyl-3-acetic acid : its Dependence on Nucleic Acid and Protein Synthesis

Abstract

THE plant growth hormone indolyl-3-acetic acid (IAA) affects almost all aspects of growth and development, and the very remarkable promotion of growth is associated with a simultaneous stimulation of water uptake, ion uptake and several metabolic processes. We have previously presented evidence to show that the plant growth substances, IAA, gibberellic acid and kinetin, all regulate the synthesis and release of nuclear RNA and that the fraction of RNA involved has a base composition complementary to that of DNA^1–4. The synthesis of nuclear protein, as well as some enzyme systems concerned with the metabolic pathways known to be affected by IAA, is also stimulated by growth promotive concentrations of IAA^4,5. In this communication we report that the lAA-induced stimulation of water uptake and ion uptake also involves a nucleic acid system, that this process is inhibited by actinomycin D and that the inhibition is removed by IAA.