Feasibility Study of Phragmites karka and Christella dentata Grown in West Bengal as Arsenic Accumulator.

A survey was undertaken, in arsenic (As) contaminated area of the Nadia district, West Bengal, India, to find native As accumulator plants. As was determined both in soil and plant parts. The results showed that the mean translocation factor of Pteris vittata L, Phragmites karka (Cav.) Trin. Ex. Steud and Christella dentata Forssk were higher than 1. It thus appeared that these plants can be efficient accumulators of As. Phytoremediation ability of C. dentata and P. karka was evaluated and compared with known As-hyperaccumulators -P. vittata and Adiantum capillus veneris L. Plants were grown in the As spiked soil (25, 50, 75 and 100 mg kg(-1)). As accumulation was found to be highest in P. vittata, 117.18 mg kg(-1) in leaf at 100 mg kg(-1) As treatment, followed by A. capillus veneris, P. karka and C. dentata being 74, 83.87 and 40.36 mg kg(-1), respectively. Lipid peroxidation increased after As exposure in all plants. However, the antioxidant enzyme activity and molecules concentration also increased which helped the plants to overcome As-induced oxidative stress. The study indicates that P. karka and C. dentata could be considered as As-accumulators and find application for As-phytoextraction in field conditions.

Phytoremediation of arsenic contaminated soil by arsenic accumulators: a three year study.

To investigate whether phytoremediation can remove arsenic from the contaminated area, a study was conducted for three consecutive years to determine the efficiency of Pteris vittata, Adiantum capillus veneris, Christella dentata and Phragmites karka, on arsenic removal from the arsenic contaminated soil. Arsenic concentrations in the soil samples were analysed after harvesting in 2009, 2010 and 2011 at an interval of 6 months. Frond arsenic concentrations were also estimated in all the successive harvests. Fronds resulted in the greatest amount of arsenic removal. Root arsenic concentrations were analysed in the last harvest. Approximately 70 % of arsenic was removed by P. vittata which was recorded as the highest among the four plant species. However, 60 % of arsenic was removed by A. capillus veneris, 55.1 % by C. dentata and 56.1 % by P. karka of arsenic was removed from the contaminated soil in 3 years.

Metabolic adaptation of Pteris vittata L. gametophyte to arsenic induced oxidative stress.

The sporophyte and gametophyte of Pteris vittata are arsenic hyperaccumulators, however, little is known about the mechanism by which the gametophyte deals with this toxic element. An in vitro system (spores grown in arsenic amended nutrient media) was used to investigate the impact of arsenic on growth of the gametophyte and the role of antioxidative systems in combating As-stress. When mature spores of P. vittata were grown in medium amended with 0-50 mg kg(-1) of arsenic (as arsenate), the arsenic concentration in the gametophyte increased, with increasing arsenate in the media, but did not inhibit the spore germination and biomass development. Increases in the level of antioxidant enzymes, superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase, and glutathione-Stransferase) and of ascorbic acid and glutathione probably enabled the gametophyte to withstand the oxidative stress caused by arsenate.

Arsenic accumulation pattern in 12 Indian ferns and assessing the potential of Adiantum capillus-veneris, in comparison to Pteris vittata, as arsenic hyperaccumulator.

The present study was undertaken to evaluate the ability of some Indian ferns to accumulate and tolerate arsenic. Twelve species of Indian ferns were exposed to 10 mg L(-1) arsenic as sodium arsenate for 15 days in hydroponic system. Depending on the arsenic uptake in the plant parts--Pteris vittata, Pteris cretica, Adiantum capillus-veneris and Nephrolepis exaltata may be categorised as arsenic accumulator. Further, A. capillus-veneris plants were grown in arsenic contaminated soil (200-600 mg kg(-1)) under green-house condition, to assess its arsenic accumulation and tolerance mechanism, in comparison to known As-hyperaccumulator--P. vittata Linn., growing in the same conditions. The experiment identified A. capillus-veneris having a potential to tolerate arsenic up to 500 mg kg(-1). The plants were analysed for the extent of oxidative stress, as a result of arsenic accumulation. A. capillus-veneris was able to detoxify the arsenic stress through induction of anti-oxidant defence system.

Effects of arsenic on nitrate metabolism in arsenic hyperaccumulating and non-hyperaccumulating ferns.

This study investigated the effects of arsenic on the in vitro activities of the enzymes (nitrate reductase and nitrite reductase) involved in nitrate metabolism in the roots, rhizomes, and fronds of four-month old Pteris vittata (arsenic - hyperaccumulator) and Pteris ensiformis (non-arsenic-hyperaccumulator) plants. The arsenic treatments (0, 150, and 300 microM as sodium arsenate) in hydroponics had adverse effects on the root and frond dry weights, and this effect was more evident in P. ensiformis than in P. vittata. Nitrate reductase and nitrite reductase activities of arsenate-treated plants were reduced more in P. ensiformis than in P. vittata. This effect was accompanied by similar decreases in tissue NO(3)(-) concentrations. Therefore, this decrease is interpreted as being indirect, i.e., the consequence of the reduced NO(3)(-) uptake and translocation in the plants. The study shows the difference in the tolerance level of the two Pteris species with varying sensitivity to arsenic.