RuBP limitation of photosynthetic carbon fixation during NH sub 3 assimilation: Interactions between photosynthesis, respiration, and ammonium assimilation in N-limited green algae

Journal Article · Wed Jun 01 04:00:00 EDT 1988 · Plant Physiology; (USA)

DOI:https://doi.org/10.1104/pp.87.2.395· OSTI ID:5560003

Elrifi, I R; Holmes, J J; Weger, H G; Mayo, W P; Turpin, D H ^[1]

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1. Queen's Univ., Kingston, Ontario (Canada)

The effects of ammonium assimilation on photosynthetic carbon fixation and O{sub 2} exchange were examined in two species of N-limited green algae, Chlorella pyrenoidosa and Selenastrum minutum. Under light-saturating conditions, ammonium assimilation resulted in a suppression of photosynthetic carbon fixation by S. minutum but not by C. pyrenoidosa. These different responses are due to different relationships between cellular ribulose bisphosphate (RuBP) concentration and the RuBP binding site density of ribulose bisphosphate carboxylase/oxygenase (Rubisco). In both species, ammonium assimilation resulted in a decrease in RuBP concentration. In S. minutum the concentration fell below the RuBP binding site density of Rubisco, indicating RuBP limitation of carboxylation. In contrast, RuBP concentration remained above the binding site density in C. pyrenoidosa. Compromising RuBP regeneration in C. pyrenoidosa with low light resulted in an ammonium-induced decrease in RuBP concentration below the RuBP binding site density of Rubisco. This resulted in a decrease in photosynthetic carbon fixation. In both species, ammonium assimilation resulted in a larger decrease in net O{sub 2} evolution than in carbon fixation. Mass spectrometric analysis shows this to be a result of an increase in the rate of mitochondrial respiration in the light.

• OSTI ID: 5560003
• Journal Information: Plant Physiology; (USA), Journal Name: Plant Physiology; (USA) Vol. 87:2; ISSN 0032-0889; ISSN PLPHA
• Country of Publication: United States
• Language: English

Related Subjects

560300* -- Chemicals Metabolism & Toxicology
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ALGAE
AMMONIUM COMPOUNDS
BIOLOGICAL EFFECTS
BIOLOGICAL VARIABILITY
CARBON DIOXIDE FIXATION
CARBON-CARBON LYASES
CARBOXY-LYASES
CELL CONSTITUENTS
CHEMICAL REACTIONS
ELECTROMAGNETIC RADIATION
ELEMENTS
ENZYMES
GENETIC VARIABILITY
INHIBITION
LYASES
MASS SPECTROSCOPY
MEMBRANE PROTEINS
METABOLISM
MITOCHONDRIA
NONMETALS
ORGANIC COMPOUNDS
ORGANOIDS
OXYGEN
OXYGEN COMPOUNDS
PHOSPHATES
PHOSPHORUS COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PLANTS
PROTEINS
RADIATIONS
RECEPTORS
RESPIRATION
RIBULOSE DIPHOSPHATE CARBOXYLASE
SPECTROSCOPY
SYNTHESIS
VISIBLE RADIATION