Peculiarities of physiological indexes of water regime in the bryophytes with a different tolerance to water deficit

N. Kyyak

Institute of Ecology of the Carpathians, NAS of Ukraine
11, Stefanyk St., Lviv 79000, Ukraine

The seasonal changes of water regime indexes (an intracellular osmotic pressure and accumulation of the osmotically active substances) in shoots of the mosses Bryum argenteum and Brachytecium salebrosum with a different tolerance to water deficit on the area of sulfur deposits dump were investigated. In the moss leaves the apical-basal gradient of osmotic pressure, which increases absorption and maintenance of water under the unfavorable hydrothermical conditions, was indicated. In the tolerant to water deficit moss Bryum argenteum the higher intracellular osmotic pressure was detected. It is concluded that osmotic pressure is the important indicator of water regime of bryophytes with different tolerance to water deficit. In mosses with different sensitivity to water deficit the differences in accumulation of the soluble sugars were founded. In Bryum argenteum shoots higher content of the soluble carbohydrates during the vegetative season and a significant increase in their concentration in summer were determined, which provide osmotic pressure regulation and protection of subcellular structures. Under the unfavorable hydrothermical conditions in the tolerant to water deficit mosses the considerable rebuilding of the nitrogen-containing compounds metabolism, which leads to an increase in the free aminoacids total contents and proline in the cells, was indicated.

Keywords: osmotic pressure, soluble carbohydrates, free aminoacids, proline, mosses

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