title: Comparison of growth, exogenous auxin sensitivity, and endogenous indole-3-acetic acid content in roots of Hordeum vulgare L. and an agravitropic mutant.
abstract: The chemically induced barley (Hordeum vulgare L.) mutation, agr, was found to be a simple recessive trait resulting in agravitropic roots and normal gravitropic shoots. The total seedling root growth was similar for mutant and wild-type roots, although the mutant had fewer roots per seed and greater elongation per root. Although the concentration of exogenous indole-3-acetic acid (IAA) required to reduce root growth by 50% (GR50) was 12 times greater for the agravitropic mutant, agravitropic and gravitropic roots were equally sensitive to exogenous applications of 2,4-dichlorophenoxyacetic acid (2,4-D) and naphthalene acetic acid (NAA). Root IAA contents, determined by high-pressure liquid chromatography (HPLC), were not different for gravitropes and agravitropes. The greater root elongation rates, lack of sensitivity to exogenous IAA, and normal endogenous IAA levels indicate that auxin-controlled growth regulation may be altered in the mutant.
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000494:pharmacology; D000085:Acetates / Q000494:pharmacology; D002523:Edible Grain / Q000502:physiology*; D006112:Gravitation; D001467:Hordeum / Q000502:physiology*; D007210:Indoleacetic Acids / Q000502:physiology*; D009154:Mutation; D009281:Naphthalenes / Q000494:pharmacology; D010937:Plant Growth Regulators / Q000502:physiology*
chemical_list: D000085:Acetates; D007210:Indoleacetic Acids; D009281:Naphthalenes; D010937:Plant Growth Regulators; D015084:2,4-Dichlorophenoxyacetic Acid; C030737:indoleacetic acid