Abstract
The use of pedunculate oak (Quercus robur L.), along with other tree species, for the afforestation of heavy metal contaminated lands is an attractive prospect. Little, however, is known of Q. robur tolerance and its antioxidative system response to heavy metal exposure. The main objective of the study was to determine the cadmium-induced changes in antioxidative system of pedunculate oak in an attempt to identify molecular mechanisms underlying Cd tolerance. This may be of great importance in respect of using Q. robur for phytoremediation purposes. As the response of the antioxidative system to heavy metal contamination can vary within species, the research was conducted on oak seedlings from two different regions of origin. Differences in antioxidative system response of seedlings derived from tested regions of origin were noticed both at the transcript and enzyme activity levels. The obtained results indicate that ascorbate peroxidase (APX; EC 1.11.1.11) and superoxide dismutase (SOD; EC 1.15.1.1) play a first barrier role in oak seedlings response to the oxidative stress caused by Cd exposure. Catalase (CAT; EC 1.11.1.6) is involved in reducing the negative effects of prolonged Cd treatment.
Highlights
Heavy metal contamination of soils is a serious problem of the modern world (Mihucz et al 2012)
The obtained results indicate that ascorbate peroxidase (APX; EC 1.11.1.11) and superoxide dismutase (SOD; EC 1.15.1.1) play a first barrier role in oak seedlings response to the oxidative stress caused by Cd exposure
lipid peroxidation (LPO) increase was observed in 50 lM Cd treated plants already after 1 day of exposure, whereas 10 lM Cd treatment caused no changes in LPO level throughout the whole experiment
Summary
Heavy metal contamination of soils is a serious problem of the modern world (Mihucz et al 2012). Cadmium is recognized as one of the most toxic pollutant due to its high mobility and low amount needed to cause the toxicity symptoms. Cd was shown to induce ultrastructural damage to chloroplasts, which subsequently affects photosynthesis and causes decline in biomass production. Plants showing high Cd tolerance revealed increased Rubisco level, mitigating Cd effect on biomass production. As cadmium causes oxidative stress (Mihucz et al 2012), an adequate antioxidative system reaction is a fundamental cell defense mechanism. The activation of antioxidative enzymes helps to protect plant against oxidative injury evoked by heavy metals (DalCorso et al 2008). Major antioxidative enzymes are superoxide dismutase (SOD; EC 1.15.1.1), catalase (CAT; EC 1.11.1.6) and ascorbate peroxidase (APX; EC 1.11.1.11) (Mittler 2002). SOD catalyzes the dismutation of O2Á- to H2O2, which is subsequently detoxified by CAT and APX (Sharma and Dietz 2009)
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