Exaggeration of desiccation stress by heavy metal pollution in Tortula ruralis: a pilot study

Glutathione pool and redox status, as well as chlorophyll fluorescencewere measured in Tortula ruralis which was treated withheavy metals and exposed to different desiccation treatments. Two hours afterre-wetting, the ratio of oxidised glutathione to total glutathione poolreturnedto the steady state level (14%) in slowly dried unpolluted plants. Cdtreatment doubled this ratio, as did rapid drying without the heavy metaltreatment. When Cd and rapid drying were applied together, the ratio of GSSGreached 45% indicating a clear additive effect of these two stressfactors. RFd, a chlorophyll fluorescence parameter followed a similar pattern.Lead did not cause the depletion of the glutathione pool but increased theratioof GSSG. It is suggested that Cd and rapid desiccation exert their damageadditively. This might also entail a lowered degree of desiccation tolerance inareas polluted with metals and therefore a retreat of the mosses to mesicmicrohabitats.