Control of nitrate and nitrite assimilation by carbohydrate reserves, adenosine nucleotides and pyridine nucleotides in leaves of Zea mays L. under dark conditions

The rate of in-vivo nitrate reduction by leaf segments of Zea mays L. was found to decline during the second hour of dark anaerobic treatment. On transfer to oxygen the capacity to reduce nitrate under dark conditions was restored. These observations led to the proposal that nitrate reductase is a r...

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Bibliographic Details
Published in:Planta 1987-12, Vol.172 (4), p.548-554
Main Authors: Watt, M.P., Gray, V.M., Cresswell, C.F.
Format: Article
Language:English
Subjects:
Agronomy. Soil science and plant productions
Anaerobic conditions
Anaerobiosis
Biological and medical sciences
carbohidratos
carbohydrates
darkness
Economic plant physiology
Enzymes
feuille
Fundamental and applied biological sciences. Psychology
glucide
hojas
Leaves
Mesophyll cells
Metabolism
nitrate
Nitrates
nitratos
nitrite
Nitrites
nitritos
Nitrogen metabolism
Nitrogen metabolism and other ones (excepting carbon metabolism)
nucleotide
nucleotides
nucleotidos
Nutrition. Photosynthesis. Respiration. Metabolism
obscuridad
obscurite
Oxygen
Plant cells
Plant physiology and development
Protoplasts
zea mays
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Summary:The rate of in-vivo nitrate reduction by leaf segments of Zea mays L. was found to decline during the second hour of dark anaerobic treatment. On transfer to oxygen the capacity to reduce nitrate under dark conditions was restored. These observations led to the proposal that nitrate reductase is a regulatory enzyme with ADP acting as a negative effector. The effect of ADP on the invitro activity of nitrate reductase and the changes in the in-vivo adenylate pool under dark-N2 and dark-O2 were investigated. It was found that ADP inhibited the activity of partially purified nitrate reductase. Similarly, the in-vivo anaerobic inhibition of nitrate reduction was associated with a build-up of ADP in the leaf tissue. Under anaerobic conditions nitrite accumulated and on transfer to oxygen the accumulated nitrite was reduced. To explain this phenomenon the following hypothesis was proposed and tested. Under anaerobic conditions the supply of reducing equivalents for nitrite reduction in the plastid becomes restricted and nitrite accumulates as a consequence. On transfer to oxygen this restriction is removed and nitrite disappears. This capacity to reduce accumulated nitrite was found to be dependent on the carbohydrate status of the leaf tissue.
ISSN:0032-0935
1432-2048
DOI:10.1007/BF00393873