Bioaccumulation and physiological effects of mercury in Pteris vittata and Nephrolepis exaltata
- 545 Downloads
Anatomical, histochemical and biochemical approaches were used to study mercury uptake and phytotoxicity as well as anti-oxidative responses in two species of ferns [Chinese brake fern (Pteris vittata) and Boston fern (Nephrolepis exaltata)], grown in a hydroponic system. The roots of both cultivars accumulated large amounts of mercury, but exhibited limited mercury translocation to shoots. Mercury exposure led to more pronounced phytotoxicity accompanied by stronger oxidative stress in the shoots of P. vittata than in N. exaltata. N. exaltata established a more effective anti-oxidative system against mercury-induced oxidative stress than did P. vittata. The activity of anti-oxidative enzymes (superoxide dismutase, catalase and glutathione reductase) increased. The reduced ascorbate (ASA) and oxidized ascorbate (DHA) are regulated. Mercury exposure led to an increase in the concentration of glutathione (GSH) in both fern species. The present study suggests that N. exaltata is more tolerant to mercury exposure than P. vittata, which has been also reported to be more tolerant to arsenic exposure. N. exaltata may thus have potential for phytostabilization of soils or phytofiltration of waste water contaminated with mercury.
KeywordsMercury Phytotoxicity Oxidative stress Pteris vittata Nephrolepis exaltata Phytoremediation
We thank Ms. Yunju Xia and Mr. Dean W. Patterson for chemical analyses. We also gratefully acknowledge the electronic microscopy study assistance provided by Ms. Amanda M. Lawrence. This research is supported by U.S. Department of Energy’s Office of Science and Technology through Cooperative Agreement DE-FC01-06EW-07040.
- Beers RF, Sizer IW (1952) A spectrophotometric method for measuring the breakdown of hydrogen peroxide by catalase. J Biol Chem 195:133–140Google Scholar
- Brooks RR (1998) Plants that hyperaccumulate heavy metals. CAB International, Wallingford, UKGoogle Scholar
- Córdoba-Pedregosa MC, Córdoba F, Villalba JM, González-Reyes JA (2003) Differential distribution of ascorbic acid, peroxidase activity, and hydrogenperoxide along the root axis in Allium cepa L. and its possible relationship with cell growth and differentiation. Protoplasma 221:57–65. doi: 10.1007/s00709-002-0069-9 CrossRefGoogle Scholar
- Gossett DR, Millhollon EP, Lucas MC (1994) Antioxidant response to NaCl stress in salt-tolerant and salt-sensitive cultivars of cotton. Crop Sci 34:706–714Google Scholar
- Halliwell B (1982) The toxic effects of oxygen on plant tissues. In: Oberley LW (ed) Superoxide dismutase, vol 1. CRC Press, Boca Raton, FL, pp 89–124Google Scholar
- Law MY, Charles SA, Halliwell B (1983) Glutathione and ascorbic acid in spinach (Spmacia oleracea) chloroplasts. Biochem J 210:899–903Google Scholar
- Reeves RD, Baker AJM (2000) Metal-accumulating plants. In: Raskin I, Ensley BD (eds) Phytoremediation of toxic metals: using plants to clean up the environment. Wiley, New York, pp 193–229Google Scholar