[Reversibility of the effects of cadmium on the growth and nitrogen metabolism in the tomato(Lycopersicon esculentum)].

In order to better understand the effects of heavy metals on the growth of plants, we decided to perform recovering experiments by following both chemical and physiological parameters in cadmium pre-stressed tomato seedlings after cadmium had been removed from the nutrient solution. The work shows that cadmium suppression results in resumption of growth activity. The biomass of leaves and stems rose steadily.

Glutamine and alpha-ketoglutarate are metabolite signals involved in nitrate reductase gene transcription in untransformed and transformed tobacco plants deficient in ferredoxin-glutamine-alpha-ketoglutarate aminotransferase.

Transformed tobacco (Nicotiana tabacum L.) plants with varying activities of the key enzyme of ammonia assimilation, ferredoxin-glutamine-alpha-ketoglutarate aminotransferase (Fd-GOGAT; EC 1.4.

Immunolocalization of glutamine synthetase in senescing tobacco (Nicotiana tabacum L.) leaves suggests that ammonia assimilation is progressively shifted to the mesophyll cytosol.

Glutamine synthetase (GS) catalyses the formation of glutamine (a major form of nitrogen transport in plants) in an ATP-dependent reaction using ammonium and glutamate. This enzyme is present in the plastids and/or in the cytosol depending on the plant or the organ examined. In order to understand the role of GS isoforms in the remobilization of leaf nitrogen, we studied the localization of GS isoenzymes during natural senescence of tobacco (Nicotiana tabacum L.

Characterization of the sink/source transition in tobacco ( Nicotiana tabacum L.) shoots in relation to nitrogen management and leaf senescence.

The metabolic, biochemical and molecular events occurring during tobacco (Nicotiana tabacum) leaf ageing are presented, with a particular emphasis on nitrogen metabolism. An integrated model describing the source/sink relationship existing between leaves of different developmental stages along the main plant axis is proposed. The results of our study show that a tobacco plant can be divided into two main sections with regards to sink/source relationships.

Simultaneous expression of NAD-dependent isocitrate dehydrogenase and other krebs cycle genes after nitrate resupply to short-term nitrogen-starved tobacco.

Mitochondrial NAD-dependent (IDH) and cytosolic NADP-dependent isocitrate dehydrogenases have been considered as candidates for the production of 2-oxoglutarate required by the glutamine synthetase/glutamate synthase cycle. The increase in IDH transcripts in leaf and root tissues, induced by nitrate or NH4+ resupply to short-term N-starved tobacco (Nicotiana tabacum) plants, suggested that this enzyme could play such a role. The leaf and root steady-state mRNA levels of citrate synthase, acotinase, IDH, and glutamine synthetase were found to respond similarly to nitrate, whereas those for cytosolic NADP-dependent isocitrate dehydrogenase and fumarase responded differently.