Growth and physiological responses in chicory towards mercury induced in vitro oxidative stress

Abstract

Plants experience oxidative stress upon exposure to heavy metals that leads to cellular damage. Plants accumulate metal ions that disturb cellular ionic homeostasis. Currently the main interest in metal accumulators lies in the field of phytoremediation when plants are used to “clean up” metal contaminants from the soil. The present study was conducted to evaluate the oxidative stress in chicory plants when subjected to different concentrations of Hg (0, 25, 50 and 75 µM). In order to study oxidative stress and Hg accumulation in chicory various morphological, biochemical and enzymatic parameters at two different stages (23 and 46 days old) were studied. The root and shoot growth, biomass accumulation declined significantly at highest Hg concentration (75 µM) and Hg accumulation was higher in roots than in shoots as indicated by translocation factor < 1. Hydrogen peroxide (H2O2) and thiobarbituric acid reactive substances content increased with increasing concentration of Hg treatments. The change in H2O2 was also revealed by in vivo histochemical detection. The osmolytes and photosynthetic pigment increased significantly up to 50 µMHg, while as decreasing slightly at higher dose (75 µM). The activities of defense enzymes viz. superoxide dismutase, catalase, ascorbate peroxidase, guaiacol peroxidase, glutathione reductase and glutathione S-transferase were found to be positively correlated with Hg-concentration. In conclusion, the chicory plants were found to possess Hg-detoxification capacity which can be recommended for remediating Hg contaminated soils.