title: Plasma membrane NADH oxidase of maize roots responds to gravity and imposed centrifugal forces.
abstract: NADH oxidase activities measured with excised roots of dark-grown maize (Zea mays) seedlings and with isolated plasma membrane vesicles from roots of dark-grown maize oscillated with a regular period length of 24 min and were inhibited by the synthetic auxin 2,4-dichlorophenoxyacetic [correction of dichorophenoxyacetic] acid. The activities also responded to orientation with respect to gravity and to imposed centrifugal forces. Turning the roots upside down resulted in stimulation of the activity with a lag of about 10 min. Returning the sections to the normal upright position resulted in a return to initial rates. The activity was stimulated reversibly to a maximum of about 2-fold with isolated plasma membrane vesicles, when subjected to centrifugal forces of 25 to 250 x g for 1 to 4 min duration. These findings are the first report of a gravity-responsive enzymatic activity of plant roots inhibited by auxin and potentially related to the gravity-induced growth response.
authors.affiliation: Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907-1333, USA.
authors.forename: E
authors.initials: E
authors.lastname: Bacon
authors.forename: D J
authors.initials: DJ
authors.lastname: Morre
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D002498:Centrifugation; D006112:Gravitation; D018522:Gravitropism / Q000187:drug effects*; D006540:Herbicides / Q000494:pharmacology; D018471:Hypergravity; D009097:Multienzyme Complexes / Q000378:metabolism*; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D010507:Periodicity; D018517:Plant Roots / Q000187:drug effects / Q000201:enzymology / Q000648:ultrastructure; D003313:Zea mays / Q000187:drug effects / Q000201:enzymology* / Q000648:ultrastructure*
chemical_list: D006540:Herbicides; D009097:Multienzyme Complexes; D015084:2,4-Dichlorophenoxyacetic Acid; C023107:NADH oxidase; D009247:NADH, NADPH Oxidoreductases