Modyfikacje pomp protonowych plazmolemy i tonoplastu w warunkach stresu solnego

W pracy wykazano, że frakcja cytosolowa z korzeni ogórków traktowanych NaCl, stymulowała plazmolemową i tonoplastową ATPazę izolowaną z roślin nie poddanych działaniu soli. Stymulujący efekt frakcji cytosolowej był eliminowany przez wysoką temperaturę i staurosporynę. Wprowadzenie jonów wapnia z ekstraktem z roślin niepoddanych działaniu soli, do zawiesiny błon izolowanych z roślin również nietraktowanych solą, stymulowało pompy protonowe. Takie rezultaty sugerowały udział specyficznych białkowych kinaz, zależnych od wapnia w aktywacji ATPaz błonowych w warunkach stresu solnego. Doświadczenia z zastosowaniem W7, antagonisty kalmoduliny, zawęziły szeroką grupę kinaz do tych zależnych od kompleksu wapń-kalmodulina. Dodatkowo wykazano, że w błonach izolowanych z korzeni ogórków traktowanych NaCl funkcjonuje antyport Na⁺/H⁺, który wyrzuca nadmiar jonów sodu z cytoplazmy.The extract from NaCl treated cucumber roots stimulated both, the plasma membrane and tonoplast ATPases isolated from unstressed plants. Stimulatory effect of the extract from NaCl treated plants was eliminated by high temperature and staurosporine. On the other hand, addition of Ca²⁺ together with extract from unstressed plants to the membrane prepared from unstressed roots stimulated both proton pumps. Such results suggested a participation of specific Ca-dependent kinases in activation of the membrane ATPases under salt stress conditions. Experiments with W7, an antagonist of calmodulin, restricted a wide group of kinases to those dependent on the calcium-calmodulin complex. Furthermore, it was found that in membranes isolated from NaCl stressed cucumber roots operated the Na⁺/H⁺ antiport, which excluded sodium ions from cytoplasm

Changes in pH and organic acids in mucilage of Eriophorum angustifolium roots after exposure to elevated concentrations of toxic elements

The presence of Eriophorum angustifolium in mine tailings of pyrite maintains a neutral pH, despite weathering, thus lowering the release of toxic elements into acid mine drainage water. We investigated if the presence of slightly elevated levels of free toxic elements triggers the plant rhizosphere to change the pH towards neutral by increasing organic acid content. Plants were treated with a combination of As, Pb, Cu, Cd and Zn at different concentrations in nutrient medium and in soil in a rhizobox-like system for 48-120 hrs. The pH and organic acids were detected in the mucilage dissolved from root surface, reflecting the rhizosphere solution. Also the pH of root-cell apoplasm was investigated. Both apoplasmic and mucilage pH increased and the concentrations of organic acids enhanced in the mucilage with slightly elevated levels of toxic elements. When organic acid concentration was high, also the pH was high. Thus, efflux of organic acids from the roots of E. angustifolium may induce rhizosphere basification