ИСТИНА

Ion exchange properties and swelling capacity of suaeda (Suaeda altissima L. Pall), spinach (Spinacia oleracea L., Matador cv.) and chickpea (Cicer arietinum L.) root cell walls were investigated under different salinity condition. It was found that, there are 3 cation-exchange groups (two types of carboxyl groups and phenolic group) and one anion-exchange group (amine group) in the plant root cell walls. The total quantities of cation exchange (Stcat) and anion exchange (Stan) groups were determined, and the quantity of functional groups of each type (Sj) was estimated, and the corresponding values of pKaj were calculated. The Stcat and Stan as well as Sj were demonstrated to be are stable at any pH and electrolyte concentration (CNa+) of the medium. The values of pKaj and Sj indicate that the root cell walls of tested plants are identical in qualitative structure of ionogenic groups but vary in the quantity of each ionogenic group. It was shown that for all types of cation exchangeable groups arranged in cell wall structure the acid properties are enhanced by the increasing of electrolyte concentration. It was found that swelling of root cell walls changes with pH, CNa+ and strongly depends on plant species. In the pH and CNa+ range covered the swelling coefficient varies in the following sequence: chickpea > spinach > suaeda. The results indicate that for tested plant species such sequence of change in swelling is connected with different cross-linked degree of the polymers in cell wall structure, different summarized quantity of carboxyl groups and different total quantity of functional groups. Based on known data and experimental results of present study it was concluded that the change in cell wall swelling in response to variances of environmental or initial conditions leads to the change in volume water flow through the plant roots. The results of this investigation point to the fact that both the transport of mineral solutes within the apoplast and the volume water flow through the plants are highly sensitive to environmental influence on the ion exchange properties of plant root cell walls. The work was supported by the Russian Foundation for Basic Research (project No 08-04-01398-а).