© International Society for Tropical Ecology Biochemical and physiological mechanisms leading to salt tolerance

Abstract: We showed that malic enzyme and F-type ATPase isolated from glycophytes and halophytes do not differ significantly in their amino acid composition. Isolated enzymes from both types of plants showed nearly identical salt sensitivity, each, but enzyme activities in fresh homogenates from halophyte leaves apparently were more salt resistant as compared to the ones from glycophytes. These results suggest that some cytosolic compounds other than the tested enzymes bring about salt tolerance. We observed distinct differences in photosynthate export out of the chloroplasts when comparing salt stress response of glycophytes and halo-phytes. In contrast to glycophytes metabolite leakage out of the chloroplasts or internal me-tabolite pool size are more strictly regulated in halophytes. Pronounced differences were ob-served, when measuring P-type ATPase activities at the plasmalemma. Apparently, most of the difference between salt tolerant plants (halophytes) and glycophytes is due to a faster and more effective response of the former bringing about ion homeostasis by adaptation of transmem-brane transport to saline conditions and coordination of metabolism. Resumen: Nosotros mostramos que la enzima málica y la ATPasa de tipo F aisladas de glicófitas y halófitas no difieren significativamente en su composición de aminoácidos. Las en