Effects of the period of glyphosate treatment on oak seedlings: phenological and physiotogical aspects

International audienc

Photosynthesis, Rubisco activity and mitochondrial malate oxidation in pedunculate oak (Quercus robur L) seedlings grown under present and elevated atmospheric CO 2

Pedunculate oak seedlings were grown at 350 and 700 μL/L CO2 in controlled chambers. After 130 days at elevated CO2, the biomass of the whole plant did not significantly increase. Photosynthesis, Rubisco activity, mitochondrial malate oxidation, carbohydrates and nitrogen contents were examined in the fourth growth flush. At 700 μL/L CO2, the leaf net photosynthetic rate was 220% higher than at 350 μL/L CO2. The decreased activity of Rubisco was accompanied by an accumulation of sucrose and glucose. The decreased oxidative capacity of crude leaf mitochondria from elevated CO2 plants was driven by the lower nitrogen and protein contents rather than by the higher carbohydrates contents in the leaves. Nevertheless, direct effects of elevated CO2 on the respiratory biochemistry cannot be excluded.Photosynthèse, activité Rubisco et oxydation mitochondriale du malate chez des semis de chêne pédonculé (Quercus robur L) élevés à des concentrations en CO2 atmosphérique actuelle et double. Des germinations de chêne pédonculé ont été élevées sous 350 et 700 μL/L de CO 2 en chambres de culture. Après 130 jours de CO2 élevé, la biomasse du plant entier n'a pas augmenté significativement. Les échanges foliaires de CO2, l'activité Rubisco, l'oxydation mitochondriale du malate, les teneurs de sucres et d'azote ont été étudiées sur des feuilles de la quatrième vague de croissance. À 700 μL/L de CO 2, le taux de photosynthèse nette foliaire augmente de 220 % par rapport à celui à 350 μL/L de CO2. La diminution de l'activité Rubisco est accompagnée d'une accumulation de saccharose et de glucose. La diminution de la capacité d'oxydation des mitochondries brutes de feuilles des plants sous CO2 élevé est reliée plutôt à la diminution des teneurs en azote et protéines qu'à l'augmentation de la teneur en sucres dans les feuilles. Néanmoins, les effets directs de l'élévation de CO2 sur la biochimie de la respiration ne sont pas exclus

Extraction and study of enzymes linked to malate metabolism in tree leaves

International audienc

Foliar CO2 fixation in bean (Phaseolus vulgaris L.) submitted to elevated ozone: distinct changes in Rubisco and PEPc activities in relation to pigment content

International audienceUsing open-top chambers, the impact of ozone (O3) on foliar carboxylases of bean (Phaseolus vulgaris L.) was investigated. From sowing, beans were exposed to non-filtered air (NF) and NF supplied with 40 (+40) and 80 (+80) nL L_1 O3. Twenty days after emergence, primary and first trifoliate leaves were sampled. Biochemical characteristics of leaves from +40 were quite similar to those from NF. Conversely, +80 induced distinct biochemical effects in primary and first trifoliate leaves. Regarding primary leaves, +80 reduced ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity by 33% whereas it stimulated phosphoenolpyruvate carboxylase (PEPc) activity by 376%. The reduction in Rubisco activity was accompanied by a decrease in both Rubisco subunit amounts and a consistent oxidative modification of the Rubisco small subunit (SSU). These changes came with a drastic loss in pigmentation. Regarding first trifoliate leaves, +80 stimulated Rubisco activity by 33% while it disturbed neither PEPc activity nor pigmentation. Surprisingly, the enhanced Rubisco activity was associated with a slight decrease in Rubisco protein quantity, which was not coupled with the formation of carbonyl groups in Rubisco-SSU

Effects of polyaromatic hydrocarbons on the forest ecosystem and woody plants

International audienc

Carbohydrate status and invertase activities in relation to survival and weak dormancy of the latent buds in Platanus acerifolia Willd

International audienc

Rhythmic growth and carbon allocation in Quercus robur. 1. Starch and sucrose

International audienc

Mycorrhiza formation and elevated CO2 both increase the capacity for sucrose synthesis in source leaves of spruce and aspen

International audienc