Bioaccumulation and biochemical effects of mercury in the plant Bacopa monnieri (L)
1996
Sinha, S. | Gupta, M. | Chandra, P.
Plants of Bacopa monnieri were treated with six different concentrations of Hg (0.01, 0.5, 1.0, 2.0, 3.0, and 5.0 microgram mL-1) for 4, 7, and 14 d under laboratory conditions. The metal accumulation in the root tissues was about five times more than in the shoots. At all the concentrations of Hg, cysteine, total -SH, reduced glutathione, and ascorbic acid contents increased in the roots of B. monnieri up to 7 d of exposure except the ascorbic acid content, which decreased above 2.0 microgram mL-1 Hg. The malondialdehyde content decreased at all the concentrations of Hg; however, protein and sugar contents decreased above 0.1 and 2.0 microgram mL-1 Hg, respectively, after 4 d of exposure in the roots of the plant. The chlorophyll content in leaves decreased significantly with an increase in metal concentrations and durations of exposure. The results suggest that an increase in cysteine, total -SH, reduced glutathione, and ascorbic acid content by Hg treatment at the initial exposure period are part of the overall expression of Hg tolerance in the plant, and the decrease in chlorophyll and protein content is a consequence of Hg toxicity at higher metal concentrations and increased period of exposure.
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