title: Influence of Substrate and Tissue Manganese on the IAA-Oxidase System in Cotton.
abstract: Tissue manganese was found to influence the indoleacetic acid (IAA) system of cotton over a wide range of concentrations. The cofactor and inhibitor activities of the IAA-oxidase system were affected as the concentration of manganese in the tissue was varied. Maximum inhibitor activity was found in leaf extracts from the plants grown in 0.5 mg/l manganese (Hoagland's level). The inhibitor activity decreased in the leaf extracts of plants grown at concentrations of manganese either higher or lower than 0.5 mg/l. Abnormally high IAA-oxidase activity was found in the leaves of plants grown in deficient levels of manganese (<0.0005, 0.005 mg/l) and the extracts from plants in the <0.0005 mg/l Mn treatment showed IAA-oxidase cofactor activity.
authors.affiliation: Department of Plant Sciences, Texas A & M University, College Station, Texas 77843.
authors.forename: D M
authors.initials: DM
authors.lastname: Taylor
authors.forename: P W
authors.initials: PW
authors.lastname: Morgan
authors.forename: H E
authors.initials: HE
authors.lastname: Joham
authors.forename: J V
authors.initials: JV
authors.lastname: Amin