Short term exposure of Lemna minor and Lemna gibba to mercury, cadmium and chromium

Abstract

The effects of mercury (Hg), cadmium (Cd) and chromium (Cr) in concentrations ranging from 0.02 to 20 mg L−1 applied for 24 h were assessed in Lemna minor and Lemna gibba by measuring changes in protein concentration, ascorbic acid, phenolics, malondialdehyde (MDA), hydrogen peroxide (H2O2), the activity of guaiacol peroxidase (G-POX) and catalase (CAT). Ascorbic acid, phenolics, catalase and guaiacol peroxidase played a key role in the antioxidative response of L. gibba. Inadequate activity of antioxidant enzymes in the L. minor resulted in MDA and H2O2 accumulation. In both used species, Hg treatment decreased protein content and increased CAT and G-POX activity, but decreased MDA and H2O2 levels. Cadmium and chromium had opposite impacts on two used Lemna species on almost all observed parameters. Enhanced antioxidative responses of L. gibba to lower concentrations of Hg, Cd and Cr indicated greater abiotic stress tolerance than L. minor.

Activation of Non‐Enzymatic Antioxidants by Lepidium sativum L. Exposed to Hg During Assisted Phytoextraction

“…An increased concentration of AA was also observed by Zengin and Munzuroglu in Phaseolus vulgaris exposed to lower concentrations of Hg. However, other studies have demonstrated that exposure to higher concentrations of Hg decreased the amount of AA and ASH in Lemna minor , L. gibba , and Triticum vulgare plant tissues . The results provide evidence that L. sativum L. shoots were able to reduce oxidative stress caused by intense production of AA, especially at high Hg concentrations.…”

Phytoremediation capacity of aquatic plants is associated with the degree of phytochelatin polymerization

“…As a result of the induced oxidative stress, their exposure to Zn and Cd metals has led to a decline in the protein concentration [19,20]. In Lemna species ascorbic acid, phenolics, catalase and guaiacol peroxidase have been found to play important roles in heavy metal detoxification processes [21]. Cd accumulation has led to an increase in H 2 O 2 and O 2 concentration and in the lipid peroxidation in the leaves of S. natans too.…”

A Comparison of Growth on Mercuric Chloride for Three Lemnaceae Species Reveals Differences in Growth Dynamics That Effect Their Suitability for Use in Either Monitoring or Remediating Ecosystems Contaminated With Mercury

“…These findings are similar to the changes in soluble protein content in L. minor reported under treatments with between 0 and 500 μM CdCl 2 (Razinger et al, 2008 ). However, Varga et al ( 2013 ) have reported direct reduction of protein content in L. minor and L. gibba after 24 h exposure to different Hg and Cd concentrations (0, 100, 200, 300, 400, 500, and 600 μM), most likely due to excessive stress in the short-term. The inability to synthesize protein at high Hg concentrations (2, 4, 8 mg/L) might be due to several reasons, such as shortage of energy, carbohydrates or a reduced level of nutrients essential for protein synthesis, such as Mg and K (Mazhoudi et al, 1997 ; Gardea-Torresdey et al, 2004 ; Wang et al, 2008 ), increased protease activity (Palma et al, 2002 ) or structural changes induced by DNA damages or damage to the photosynthetic system (Ates et al, 2004 ; Gardea-Torresdey et al, 2004 ).…”

“…A range of protective substances, including antioxidant enzymes (SOD, CAT, POD), soluble proteins, flavonoids, and other phenolics have been shown to accumulate in plants as an adaptive mechanism for coping with certain stresses (Horling et al, 2003 ; Mittler et al, 2004 ; Sharma and Dietz, 2009 ; Varga et al, 2013 ). Each enzyme has a different role to play in plant protection; SOD converts superoxide to H 2 O 2 (Mishra et al, 2006 ), whilst CAT and POD breakdown the H 2 O 2 (Scandalios et al, 1994 ).…”

“…This processes resulted in treated water that was below both the maximum permitted concentration of Hg in drinking water (1.0 μg/L) and the permitted discharge limit of wastewater (10.0 μgL/L) set by China and USEPA. A comparative study showed that antioxidative enzymes can be activated within 24 h exposure to Hg although these enzymes are activated at lower Hg concentrations in L. gibba than L. minor (Varga et al, 2013 ). However, to date there has been no extensive study providing side-by-side comparisons of different duckweed species under various Hg concentrations.…”