A short-term decrease in nitrogenase activity (C2H2 reduction) is induced by exposure of soybean shoots to their CO2 compensation point

Photosynthesis and nitrogenase acetylene-reducing activity (ARA) were measured in soybeans (Glycine max [L.] Merr.) in which the shoots were exposed for 48 h to 60 microliter L-1 CO2, a value corresponding to their CO2 compensation point. Six hours after the beginning of the light period at low CO2,...

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Bibliographic Details
Published in:Plant physiology (Bethesda) 1995-08, Vol.108 (4), p.1455-1460
Main Authors: Vidal, R. (Institut National de la Recherche Agronomique, Montpellier, France.), Gerbaud, A, Vidal, D, Drevon, J.J
Format: Article
Language:English
Subjects:
ACETILENO
ACETYLENE
Agronomy. Soil science and plant productions
Alkynes
atmospheric pressure
Biological and medical sciences
BRADYRHIZOBIUM
Carbon dioxide
DIFFUSION
DIFUSION
DIOXIDO DE CARBONO
DIOXYDE DE CARBONE
diurnal variation
Economic plant physiology
FOTOSINTESIS
Fundamental and applied biological sciences. Psychology
Genetics
GLYCINE MAX
Life Sciences
NITROGENASA
NITROGENASE
NODOSITE RACINAIRE
Nodules
NUDOSIDADES RADICULARES
OXIGENO
Oxygen
OXYGENE
Parasitism and symbiosis
PERMEABILIDAD
PERMEABILITE
permeability
Photophase
PHOTOSYNTHESE
Photosynthesis
Plant physiology and development
Plant roots
Plants
Plants genetics
PRESION ATMOSFERICA
PRESSION ATMOSPHERIQUE
RACINE
RAICES
REDUCCION
REDUCTION
Respiration
RITMOS BIOLOGICOS
root nodules
RYTHME BIOLOGIQUE
shoots
Soybeans
Symbiosis
Symbiosis (nodules, symbiotic nitrogen fixation, mycorrhiza...)
TALLO
TIGE
TRANSPIRACION
TRANSPIRATION
Whole Plant, Environmental, and Stress Physiology
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Summary:Photosynthesis and nitrogenase acetylene-reducing activity (ARA) were measured in soybeans (Glycine max [L.] Merr.) in which the shoots were exposed for 48 h to 60 microliter L-1 CO2, a value corresponding to their CO2 compensation point. Six hours after the beginning of the light period at low CO2, the ARA started to decrease, reaching a rate of 50% of the control rate in 14 to 24 h and 20% of the control rate in 34 to 38 h after the beginning of the CO2 treatment. At these times, there was no net photosynthesis, and the transpiration rate was 20% lower than that in the control plants. An increase in the partial pressure of O2 around the nodules alleviated this inhibition of ARA. The maximal ARA achieved at 40 kPa O2 was 3 times higher than that at 20 kPa O2 and similar to the maximal ARA of the control plants. It was argued that the decrease in ARA of soybean exposed to the CO2 compensation point was due to a decrease in the nodule's permeability to O2 diffusion
ISSN:0032-0889
1532-2548
DOI:10.1104/pp.108.4.1455