The identification of the primary toxicity mechanisms of excess cations is hampered by the large array of potential cation ligands present in plant cells. Cation tolerance mechanisms are also poorly established, mainly because of the lack of experimental designs that allow to correlate the maintenance or inhibition of growth with the compartmentation and/or detoxification of the toxic cations. In the present project this correlation will be studied during the initial periods of reponse. Such a cronological approach is possible due to the methodological advances made by our team in the fields of high resolution (10 micrometres) monitoring of root elongation, determination of water relation parameters responsible for root cell elongation (root and cell pressure probe), subcellular compartmentation (EDAX, cytochemical and fluorescence methods), analysis of chelating substances (phytochelatins, organic acids), and methods of phytohormone analysis. Experiments concerning different cation toxicities wil be performed with plant species or varieties with clear different tolerance: tropical corn varieties differing in Al3+ and H+ tolerance, "Phaseolus vulgaris" and "Sinapsis alba" as Cd and Zn sensitive species, and "Thlaspi caerulescens" as Zn and Cd tolerant species, and "Mendicaggo arboerea ssp arborea" as Na+ sensitive in comparison to the "M. arborea ssp citrina" wich is Na+ tolerant.
|Effective start/end date||1/07/95 → 1/07/98|