The work addresses mechanisms of salinity tolerance in higher plants. Previous results showed that activation of inositol biosynthesis constitutes one essential aspect of a plant's adaptive response to excess sodium influx. The investigators concentrate on two aspects, of biochemical characterization of the enzymes of the pathway and the flux through the pathway in stressed plants and inositol transport. They will obtain a complete description of the metabolic flux that is necessary to sustain inositol concentrations high enough for the synthesis of membrane phospholipids and signaling molecules which utilize inositol. The characterization of a recently detected sodium/inositol symporter protein, its expression characteristics and response to salt stress signaling, will be pursued. Data indicate that sodium-inositol co-transport might be the mechanism that synchronizes photosynthesis (carbon fixation), growth and sodium uptake. This aspect of work has the potential of changing a dogma held by plant physiologists, assuming sodium/proton antiport as a tolerance mechanism. That the inositol-dependent uptake of sodium into the leaves is the controlling factor in salt stress tolerance.
