PEP carboxylase in a leguminous plant : Medicago sativa

International audienc

Molecular characterization of a gene encoding a vegetative storage protein (CiVPS) from Cichorium intybus and its expression in the root and shoot in relation to nitrogen status and pathogen resistance

http://dx.doi.org/10.1111/j.1399-3054.2004.00366.xInternational audienc

Purification and properties of tobacco ferredoxin-dependent glutamate synthase, and isolation of corresponding cDNA clones

International audienc

Response of two wheat genotype to long-term salinity stress in relation to oxidative stress and osmolyte concentration

Effect of long-term salinity stress was studied in wheat, Karim (tolerant) and Om Rabiaa (moderately tolerant) under control and two levels of salinity (100 and 200 mM NaCl). Salinity stress decreased relative water content (RWC), chlorophyll (CHL), carotenoids (CAR), membrane stability index (MSI), and increased hydrogen peroxide (H2O2), thiobarbituric acid reactive substances (TBARS), proline, glycine-betaine (GB), soluble sugars, superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR) activity in both the genotypes and at all the stages. Salinity induced decrease in RWC, CHL, CAR, MSI, were significantly higher in Om Rabiaa than more tolerant Karim. Karim recorded higher activity of SOD, CAT, GR, as well as contents of proline, soluble sugar, GB and K, and comparatively lower H2O2 and TBARS contents compared with Om Rabiaa. Om Rabiaa also showed higher Na and Na/K ratio. Results show that salinity tolerance of Karim as manifested by lower decrease in biomass is associated with higher antioxidant activity, osmolyte concentration and potassium contents, and lower H2O2, TBARS and sodium contents than Om Rabiaa

The expression of the tobacco genes encoding plastidic glutamine synthetase of ferredoxin-dependent glutamate synthase does not depend on the rate of nitrate reduction, and is unaffected by suppression of photorespiration

International audienc

Long-term salt stress responsive growth, carbohydrate metabolism, proline and anti-stress enzymes in Nicotiana tabaccum

We investigated the long-term responses of tobacco tissues to salt stress, with a particular interest for growth parameters, proline (Pro) accumulation, and carbohydrate metabolism. Exposure of 17-day-oldtobacco plants to 0.2 M NaCl was followed by a higher decrease in dry matter in roots than shoots with a decrease of both Chlorophyll a and b. Analysis of potassium, sodium and chloral accumulation showed dramatic effect to K+ accumulation especially in shoots, whereas Na+ and Cl- accumulation were strongly increased in shoots with NaCl treatment, but with minor effects in the roots. Salinity stress conditions induced a strong increase in sugar free content in the shoot and root and Pro and 2-oxoglutarate biosynthesis in tobacco tissues. However, salt-stress resulted in significant increase in the activity of NADPH and NADH malate dehydrogenase dependency, particularly in the roots, and this effect was reversed with NADP+ and NAD+-dependent malate dehydrogenase, but the activity of these enzymes was also maintained significantly higher in the absence of NaCl. Significant decreases in NADPH-depend isocitrate dehydrogenase was also observed after long-term salt treatment in tobacco plants. In addition, a gradual increase was observed in the in vitro aminating GDH activity, but the in vitro deaminating activity remained unchanged under salinity stress. These results confirmed thehypothesis that the salinity-generated MDH and GDH induction act as anti-stress enzymes in ammonia detoxification and production of Glu for Pro synthesis.Keywords: Tobacco, carbohydrate metabolism, salinity stres