Carbohydrate Status of Halophytes in the Littoral of the White Sea.

The content of nonstructural carbohydrates (glucose, fructose, sucrose, starch) and activities of sucrose-utilizing enzymes (vacuolar, apoplastic, and cytoplasmic invertases, as well as sucrose synthase) were examined in halophyte plants Triglochin maritima L. (sea arrowgrass), Tripolium vulgare Ness. (sea aster), and Glaux maritima L. (sea milkwort) inhabiting the littoral zone of the White Sea coast. Studies of plants growing in tidal cycle conditions revealed species-specific differences in sugar content and the activity of sucrose-metabolizing enzymes. T. maritima featured high concentrations of monosaccharides in leaves and elevated content of sucrose and storage starch in underground organs. T. vulgare was characterized by low monosaccharide content and the activated synthesis of sucrose that is deposited in stems and plays the main role in maintaining the plant osmotic balance. G. maritima occupies a special place: unlike other species, it accumulates abundant starch reserves in aboveground and underground organs. This species is a crinohalophyte. Its protection against ion toxicity is mediated by the release of excess toxic ions via salt-removing glands, while mineral nutrition is assisted by the mycorrhiza. The above differences show that various littoral species adapt to salinity conditions in different ways, depending on their origin and biological features. [ABSTRACT FROM AUTHOR]