Nickel hyperaccumulators

Nickel hyperaccumulator plants Allysum spp. various locations ... 

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

Serpentine soils have high levels of heavy metals (Ni, Co, Cr), and low levels of important plant nutrients (P, Ca, N). Because of these inhospitable conditions, serpentine soils support a specialized flora, including such plant species as the nickel hyperaccumulator Alyssum bertolonii. In a study that examined bacterial communities at various distances from A. bertolonii roots in different serpentine areas, it was found that the bacterial communities possessed high genetic diversity... 

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. 

Wenzel, W.W., Bnnkowski, M., Puschenreiter, M., Horak, O., 2003. Rhizosphere characteristics of indigenonsly growing nickel hyperaccumulator and excinder plants on serpentine soil. Environ. PoU. 123, 131-138. 

Salt, D.E., Kato, N., Kramer, U., Smith, R.D., Raskin, 1., 2000. The Role of Root Exudates in Nickel Hyperaccumulation and Tolerance in Accumulator and Nonaccumulator Species of Thlaspi. In Terry, N., Banuelos, G. (Eds.), Phytoremediation of Contaminated Soil and Water. CRC Press LLC, Boca Raton, FL, pp. 189-200. 

Robinson BH, Brooks RR, Howes AW, Kirkman JH, Gregg PEH. (1997). The potential of the high-biomass nickel hyperaccumulator Berkheya coddii for phytoremediation and phytomining. Journal of Geochemical Exploration 60 115-126. 

Nickel-tolerant or accumulator species of plants are likely to be found only on nickel-rich soils. Hyperaccumulator species usually grow on relatively infertile nickel-rich serpentine soils and contain more than 10,000.0 mg Ni/kg DW. Leaves from some genera of nickel hyperaccumulator plants, including Alyssum, Homalium, and Hybanthus, growing on soils derived from volcanic rocks, which are rich in ifickel, accumulate nickel to concentrations of 120,000.0 mg kg DW. Nickel is bound as a citrate complex in hyperaccumulator plants from New Caledonia however, nickel accumulator plants from other locations do not contain unusually high levels of citrate, and nickel is not present as a citrate complex but as a carboxylic acid complex. 

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. 

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. 

The nickel content of most natural vegetation is 0.05-5 ppm on a dry weight basis (NAS 1975). Near source areas, nickel on plants may be elevated because of direct foliar deposition. Some species of plants have the ability to hyperaccumulate nickel (Brooks 1980). The concentration in the leaves of Alyssum bertolonii contained 120 ppm nickel (12%). These plants are thought to produce organic ligands that complex with nickel. 

Brooks RR. 1980. Hyperaccumulation of nickel by terrestrial plants. In Nriagu JO, ed. Nickel in the environment. New York, NY John Wiley and Sons, 410-413. 

Fig. 4-1. Histogram showing nickel concentrations in the gznm Alyssum. There are two distinct populations including hyperaccumulators with > 1000 pg g l Ni in dried tissue.

Fig. 4-2. World map showing the locations of hyperaccumulators of copper, cobalt, nickel, and zinc.

Table 4-3. Hyperaccumulators of nickel (maximum concentration in gg g 1 dry weight).

Hyperaccumulators of Ni ( nickel plants ) are distributed throughout the world but only in regions that have not previously been glaciated. The main centres of distribution are shown in Fig. 4-2. The presence of these plants only in non-glaciated regions is probably a temporal factor. Presumably plant evolution and adaptation to the hostile environment of nickel-rich soils is a process considerably longer than the 10000 years that have elapsed since the last period of glaciation. 

Hyperaccumulation of Ni appears to be a strategy where genera such as Alyssum have been able to evolve a physiological tolerance to phytotoxic nickel-rich soils, and avoid competition from other species by flourishing in environments so hostile, that often Alyssum is the only coloniser of the area. 

Until recently, there had been no record of nickel plants from South America. However, Brooks et al. (1990) have now identified 12 hyperaccumulators from ultramafic soils in Goias State. Among them is a Jatropha sp. (Euphorbiaceae) with a creamy latex containing 1.35% Ni on a dry weight basis. This is analogous to Sebertia acuminata from New Caledonia. 

Hyperaccumulation of metallic elements in plants as reviewed above, is likely to draw increasing attention from scientists throughout the world for the reasons outlined in the introduction to this chapter. Studies on nickel plants could well involve scientists from such diverse fields as ecology, biogeography, mineral exploration, evolutionary biology, taxonomy, physiology, phytochemistry, and even archaeology (phyto-... 

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. 

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