Cadmium induces cellular pH changes in Elodea canadensis and causes external basification
(English)Article in journal (Refereed) Submitted
Earlier investigations showed that Elodea canadensis causes a basification of the surrounding medium in the presence of cadmium. This study was aimed to investigate the mechanism by which Cd causes this plant to increase the surrounding water pH. Cd-induced pH changes in cytosol, vacuole and apoplastic regions of E. canadensis were monitored by fluorescence microscopy and pH-specific fluorescent dyes. Since cytosolic Ca2+ and pH homeostasis are closely linked, the cytosolic calcium [Ca2+]cytwas also investigated after Cd treatment. Cd binding to the cell walls of E. canadensis was investigated after cultivation of plants at different fixed pH. We developed a new enzymatic method for the isolation of protoplasts from E. canadensis leaves. Cd exposure resulted in a subsequent increase in both cytosolic and vacuolar pH of leaf protoplasts and concomitant rise in the [Ca2+]cyt. Changes in [Ca2+]cyt and [pH]cyt followed the same dynamics upon Cd addition, but the changes in [pH]cyt seemed to be prior to the [Ca2+]cyt changes. Cd treatment decreased the apoplastic pH by 0.85 units and Cd contents of cell walls were enhanced at low pH. In conclusion, Cd exposure decreased the apoplastic pH of E. canadensis and resulted in Cd binding to the cell walls which may prevent Cd influx to the cytosol. The results suggest that the Cd-induced apoplastic acidification can be one of the mechanisms to increase the surrounding medium pH by E. canadensis shoots.
Cadmium, Cytosolic pH, Cytosolic Ca2+, Vacuolar pH, Apoplastic pH, Protoplasts, Elodea canadensis
Research subject Plant Physiology
IdentifiersURN: urn:nbn:se:su:diva-64326OAI: oai:DiVA.org:su-64326DiVA: diva2:457077
In thesis, Mechanisms behind pH changes by plant roots and shoots caused by elevated concentration of toxic elements2011-11-162011-11-162011-11-17Bibliographically approved