Cellular basis of salinity tolerance in plants

Glycophytes and halophytes are believed to have salt tolerance mechanisms that occur at the cellular level. One facet of the cellular mechanisms concerns the elements of the protoplasm. Variations in the response of plasma membrane permeability in salt sensitive and tolerant genotypes to salinity are explained by differences in composition and/or structure of the plasma membrane. Changes in plasma membrane lipid composition are evident upon salt exposure. Changes in protein-lipid interactions may also be involved in plasma membrane permeability variations. Agents that accumulate under salinity and have membrane protective function mitigate cellular alterations brought about by salinity-induced plasma membrane disruption. It is obvious that salt adaptation mechanisms depend on preservation of plasma membrane integrity under salt stress. Cytoplasmic viscosity responds differently to salt imposition in genotypes contrasting in salt tolerance, reflecting differences in cytoplasm structure and composition. Results also support a cytoplasmic basis for salt tolerance. Data indicate absence of association of osmotic adjustment and adaptation to salinity. More information is needed to interpret the response of cytoplasmic streaming to salinity. Assays of protoplasmic qualities, such as cell membrane permeability and cytoplasmic viscosity, will provide an easy and fast test for screening relatively large numbers of cultivars for salt tolerance. (C) 2004 Elsevier B.V.. All rights reserved.