Effects of nitrite, chlorate, and chlorite on nitrate uptake and nitrate reductase activity

Effects of NO2(-), ClO3(-), and ClO2(-) on the induction of nitrate transport and nitrate reductase activity (NRA) as well as their effects on influx into roots of intact barley (Hordeum vulgare cv Klondike) seedlings were investigated. A 24-h pretreatment with 0.1 mol m-3 NO2(-) fully induced NO3(-...

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Bibliographic Details
Published in:Plant physiology (Bethesda) 1992-10, Vol.100 (2), p.644-650
Main Authors: Siddiqi, M.Y, King, B.J, Glass, A.D.M
Format: Article
Language:English
Subjects:
ABSORCION DE SUSTANCIAS NUTRITIVAS
ABSORPTION DE SUBSTANCES NUTRITIVES
ACTIVIDAD ENZIMATICA
ACTIVITE ENZYMATIQUE
ANION
ANIONES
Barley
Biological and medical sciences
chlorate
Chlorates
CHLORE
chlorite
CLORO
effects on
Enzymes
Fundamental and applied biological sciences. Psychology
HORDEUM VULGARE
ION
IONES
Kinetics
Membranes and Bioenergetics
Metabolism
NITRATE
NITRATE REDUCTASE
Nitrates
NITRATO REDUCTASA
NITRATOS
nitrite
Nitrites
Nitrogen metabolism
Plant physiology and development
Plant roots
Plants
Pretreatment
RACINE
RAICES
Seedlings
transport
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Summary:Effects of NO2(-), ClO3(-), and ClO2(-) on the induction of nitrate transport and nitrate reductase activity (NRA) as well as their effects on influx into roots of intact barley (Hordeum vulgare cv Klondike) seedlings were investigated. A 24-h pretreatment with 0.1 mol m-3 NO2(-) fully induced NO3(-) transport but failed to induce NRA. Similar pretreatments with ClO3(-) and ClO2(-) induced neither NO3(-) transport nor NRA. Net ClO3(-) uptake was induced by but not by ClO3(-) itself, indicating that and ClO3(-) transport occur via the NO3(-) carrier. At the uptake step, NO2(-) and ClO2(-) strongly inhibited NO3(-) influx; the former exhibited classical competitive kinetics, whereas the latter exhibited complex mixed-type kinetics. ClO3(-) proved to be a weak inhibitor of NO3(-) influx (Ki = 16 mol m-3) in a noncompetitive manner. The implications of these findings are discussed in the context of the suitability of these NO3(-) analogs as screening agents for the isolation of mutants defective in NO3(-) transport
ISSN:0032-0889
1532-2548
DOI:10.1104/pp.100.2.644