Hyperaccumulating plant

Soil. The first reported field trial of the use of hyperaccumulating plants to remove metals from a soil contaminated by sludge appHcations has been reported (103). The results were positive, but the rates of metal uptake suggest a time scale of decades for complete cleanup. Trials with higher biomass plants, such as B.juncea, are underway at several chromium and lead contaminated sites (88), but data are not yet available. 

Nickel is localized predominantly in the epidermal and subepidermal of the leaves. However, in leaves of some hyperaccumulator plants such as T. caerulescens and T. goesingense, Ni and Zn are found mainly in vacuoles (Salt and Kramer, 2000). Trace elements also are inactivated in the vacuoles as high-affinity low-molecular-weight metal chelators (such as Cd-phytochelatin complex), providing plants with trace element tolerance. Some Ni in leaves is found to be associated with cell wall pectates as well. 

However, some plants can accumulate more than 0.1% of Pb, Co, Cr, and more than 1% of Mn, Ni and Zn in the shoots. These accumulator plants are called hyperaccumulators. To date, there are approximately 400 known metal hyperaccumulator plants in the world (Baker and Walker, 1989). Thlaspi caerulescens, Alyssum murale, A. lesbiacum, A. tenium are Zn and Cd hyperaccumulators. Brassica juncea, a high-biomass plant, can accumulate Pb, Cr(III), Cd, Cu, Ni, Zn, Sr, B and Se. Thlaspi caerulescens accumulates Ni. Hybrid poplar trees are reported to phytoremediate Cd and As contaminated soils. A Chinese brake fem, Pteris vittata, is an As hyperaccumulator (Ma et al., 2001). 

Nickel hyperaccumulator plants Allysum spp. various locations ... 

Lichen, Umbilicaria sp. whole 16 km vs. 90 km from nickel smelter Terrestrial vegetation Hyperaccumulator plants Most species Vegetables... 

Kramer U, Grime GW, Smith JAC, Hawes CR, Baker AJM. Micro-PIXE as a technique for studying nickel localization in leaves of the hyperaccumulator plant Alyssum lesbiacum. Nucl Instr Methods B 1997 130 346-350. 

Chaney R. L., Angle J. S., Wang A. S., McIntosh M.S., Broadhurst L., and Reeves R. D., 2005, Phytoextraction of soil Cd, Ni and Zn using hyperaccumulator plants to alleviate risks of metal contaminated soils requiring remediation. International Workshop Current developments in remediation of contaminated lands p. 39, 27-29 October 2005. Pulawy, Poland. 

Mosses, 4 species isolated areas Nickel hyperaccumulator plants Allysum spp. various locations Flowers Fruits Leaves Roots Seeds Stems... 

Al-Najar, H., Schulz, R., and Romheld, V. (2003). Plant availability of thallium in the rhizo-sphere of hyperaccumulator plants A key factor for assessment of phytoextraction. Plant Soil 249, 97-105. 

Hyperaccumulating plant species represent perhaps the ultimate in plant tolerance to extremely hostile edaphic environments. They can thrive in soils that would kill... 

Hyperaccumulating plants have been the subject of several phytochemical studies because unlike most other plants, milligram rather than microgram quantities of organometallic complexes can be separated from the plant tissue. For the sake of brevity however, this topic is not addressed in this chapter (see Baker and Brooks, 1989 for further information). 

Hammer, D., Keller, C., McLaughlin, M. J., and Hamon, R. E. (2006). Fixation of metals in soil constituents and potential remobihzation by hyperaccumulating and non-hyperaccumulating plants Results from an isotopic dilution study. Environ. Pollut. 143, 407-415. 

Schwartz, C., Morel, J. L., Saumier, S., Whiting, S. N., and Baker, A. J. M. (1999). Root architecture of the Zn-hyperaccumulator plant Thlaspi caerulescens as affected by metal origin, content and localisation in soil. Plant Soil 208, 103-115. 

Boominathan, R., Saha-Chaudhury, N.M., Sahajwalla, V., and Doran, PM. 2004. Production of nickel bio-ore from hyperaccumulator plant biomass Applications in phytomining. Biotechnology and Bioengineering, 86 243-50. 

Figures 1 and 2 show relationships among concentrations of U and selected major and trace elements in spinach leaves and petioles, respectively. It is noteworthy that concentrations of U in spinach were significantly positively correlated (p<0.01) with concentrations of Fe and A1 in both leaves and petioles. These relationships suggested that the absorption and transport processes of U in spinach could be related to those of Fe and Al, as was also suggested by Kametani et al. who showed that plants with higher Fe concentrations tended to absorb more U. Less U was extracted by 1 mol L ammonium acetate solution from soil (Table 2), meaning that U in soil was less available to plants. Spinach favours neutral-to-weak alkaline conditions and has the ability to acquire insoluble mineral nutrients such as Fe under neutral-to-alkaline conditions. Helal et al. compared spinach and beans with respect to the ability of the root to uptake Fe and found that spinach root absorbed Fe more efficiently. The differences in Cu, Zn, and Cd uptake by two spinach cultivars were attributed to different abilities to exude oxalate, citrate, and malate from root l The application of organic acids to soil facilitated the phytoextraction of U by hyperaccumulator plants thus, those root exudates could induce U dissolution from soil. Since part of U is associated with Fe and Al minerals in the soil it was likely that the absorption of U was accompanied by Fe and Al absorption, possibly triggered by the secretion of protons or organic acids to solubilise Fe and Al from soil.

Mengoni, A., Grassi, E., Barzanti, R., Biondi, E. G., Gonnelli, C., Kim, C. K., and Bazzicalupo, M. (2004). Genetic diversity of bacterial communities of serpentine soil and of rhizosphere of the nickel-hyperaccumulator plant Alyssum bertolonii. Microb. Ecol. 48, 209-217. 

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