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Ion exchange properties of root cell walls of 50-to 60-day-old plants of Suaeda altissima L., grown in nutrient medium in the presence of different NaCl concentration (0.3, 250, 750 mM) were investigated. For all growth conditions, the ion exchange capacity of the cell walls was estimated at various pH values and at different salt concentrations. The total amount of cation and anion exchange groups in the cell walls was determined. It is shown that four ionogenic groups in the polymeric structure of the halophyte cell walls are always observed independently of growth conditions: three are cation exchangeable, and one exchanges anions. The amount of the functional groups of each type is estimated, and the corresponding values of pK j a are calculated. It is shown that acidic properties are enhanced for all types of cation exchangeable groups by increasing electrolyte concentration (NaCl) in the nutrient solution. At the level of 'optimal salinity' (250 mM NaCl) the amount of polygalacturonic acid groups in cell walls is approx. 1.5 times greater than for the plants grown at either low (0.3 mM NaCl) or high salinity (750 mM NaCl). Ion exchange capacities of the root cell walls of the halophytes grown in different salt concentration are discussed in terms of S. altissima adaptation to salt stress.

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We have done a comparative study of ion status, growth and biochemical parameters in shoots and roots of seablite (Suaeda altissima (L.) Pall.) and spinach (Spinacia oleracea L.) grown with different salinity levels in the medium (0.5 -750 mМ). A distinctive feature of the halophyte was a high Na + content in tissues at its low concentration in the medium (0.5 mM). In these conditions, Na + accumulation in seablite roots was four-fold higher than in spinach roots, and Na + content in seablite leaves was almost 20-fold higher than in spinach. Together with an increase in sodium concentration in the medium, K + content decreased six-fold in seablite leaves, while in spinach it did not decrease so drastically. We can suppose that in the halophyte, some processes occur only in the presence of sodium, and these functions of sodium cannot be fully fulfilled by potassium. Analysis of protein and total nitrogen content in tissues shows that at high salinity, the ability to synthesize non-protein nitrogen-containing compounds increases in the halophyte and decreases in the glycophyte. Data on proline content dynamics show that its increase in tissues of spinach (salinity levels 150 and 250 mМ) and seablite (salinity levels 0.5 and 750 mМ) is an indicator of plant injury. In seablite and spinach, proline is not a major osmoregulator. Its concentration both in roots and leaves was no more than 2.5 µmol/g fresh weight. The data presented in this work concern the accumulation and distribution of Na + , Cl − , K + and 3 NO  ions, as well as growth and biochemical parameters. Our data show that the development of adaptation reactions in the whole plants in the conditions of high salinity is determined by morphofunctional systems and their interaction.

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