Author/Editor     Razinger, Jaka; Dermastia, Marina; Drinovec, Luka; Drobne, Damjana; Zrimec, Alexis; Dolenc-Koce, Jasna
Title     Antioxidative responses of Duckweed (Lemna minor L:) to short-term copper exposure
Type     članek
Source     Environ Sci and Pollut Res
Vol. and No.     Letnik 14, št. 3
Publication year     2007
Volume     str. 194-201
Language     eng
Abstract     Goal, Scope and Background. Elevated concentrations of copper in the environment result in accumulation of the metal in plants and cause an increase in reactive ox:idative species (ROS). The first response to elevated amounts of ROS is increased levels of enzymatic and non-enzymatic antioxidants that reduce oxidative stress. The aim of our study was to evaluate the early stages of antioxidative responses to the low copper concentrntions usually present in moderately polluted environments. In addition, some other parameters were examined to evaluate the effect of copper on plants. Methods. Duckweed (Lemna minor L.) was exposed to different concentrations of copper sulphate for up to 24 hours. Glutathione concentration and enzymatic activities of catalase, guaiacol peroxidase and glutathione reductase were measured spectrophotometrically. Additionally, delayed and prompt chlorophyll fluorescence was measuced by luminometry and fluorometrv, respectively. The accumulation of copper in plants exposed for 24 hours to various concentrations of copper sulphate was measured by flame atomic absorption spectrophotometry. Results. The treatment of plants with copper sulphate resulted in an immediate decrease of the glutathione pool, which was replenished after 24 hours at CuS04 concentrations lower than 2 micro M. Higher CuSO4 concentrations caused a decrease of reduced glutathione. The responses of the antioxidant enzymes glutathione reductase, guaiacol peroxidase and catalase to CuSO4 differed during the first six hours of exposure, but their enzyme activities all increased aher 24 hours of exposure. All these enzymes displayed biphasic activity curves with maximum values between 0.5 micro M and 1 micro M CuSO4. The response of guaiacol peroxidase was the most pronounced and statistically significantly specific and that of catalase the least. (Abstract truncated at 2000 characters)
Descriptors     PLANTS
COPPER
CHLOROPHYLL
FLUORESCENCE
CATALASE
GLUTATHIONE REDUCTASE
GLUTATHIONE
REACTIVE OXYGEN SPECIES