Alain Gerbaud

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Gas exchanges of wheat (Triticum aestivum L. cv. Courtot) shoots were measured before and during a water stress. While photosynthesis, transpiration and dark respiration decreased because of the stress, photorespiration increased initially, up to a maximum of 50% above its initial value. The CO2 concentration in the intercellular space was calculated from(More)
RNA transcript levels of Arabidopsis plants, infected by the rhizobacterium Pseudomonas thivervalensis (strain MLG45), and axenic control plants were compared using cDNA microarrays representing approximately 14 300 genes. The analysis revealed an increase of defence-related transcripts in the shoots of bacterized plants relative to control (axenic) plants.(More)
The 24 h O2 uptake and release together with the CO2 balance have been measured in two CAM plants, one a non-succulent Sempervivum grandifolium, the other a succulent Prenia sladeniana. The O2 uptake was estimated by the use of 18O2. It was found that the mean hourly O2 uptake in the light was 7 times that in the dark for Sempervivum and 5 times that for(More)
Many plant genes are responsive to sugars but the mechanisms used by plants to sense sugars are unknown. A genetic approach has been used in Arabidopsis to identify genes involved in perception and transduction of sugar signals. For this purpose, an in vivo reporter system was established consisting of the light- and sugar-regulated plastocyanin promoter,(More)
This study examines the capacity of intact spinach (Spinacia oleracea L.) chloroplasts to fix (14)CO(2) when supplied with Benson-Calvin cycle intermediates in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU). Under these conditions, substantial (14)CO(2) fixation occurred in the light but not in the dark when either dihydroxyacetone(More)
Unidirectional O(2) fluxes were measured with (18)O(2) in a whole plant of wheat cultivated in a controlled environment. At 2 or 21% O(2), O(2) uptake was maximum at 60 microliters per liter CO(2). At lower CO(2) concentrations, it was strongly inhibited, as was photosynthetic O(2) evolution. At 2% O(2), there remained a substantial O(2) uptake, even at(More)
All measurements of photorespiration and gross photosynthesis in leaves, whether using isotopes or not, are underestimated because of the recycling of O(2) or CO(2). On the basis of a simple diffusion model, we propose a method for the calculation of the recycling and the corresponding underestimation of the measurements. This procedure can be applied when(More)
The rate of HCO(3) (-) uptake by the red macroalga Chondrus crispus has been investigated. Unbalanced concentrations of free CO(2) and HCO(3) (-), generated by the photosynthetic activity, were detected in steady state conditions by using an exchange column apparatus linked to an assimilation chamber. Observing the variations of this gradient as influenced(More)