Hyperaccumulator

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Hyperaccumulators are plants that thrive in soils with high concentrations of metal ions, absorb them with the roots and enrich them in their tissues ( bioaccumulation ). The high concentration of the metals can also have a highly toxic effect on clans (local populations, varieties or subspecies) of the hyperaccumulating plant species that are not specially adapted , so it may not be a property of the entire species, but only certain local clans of it.

The first such plant was Pycnandra acuminata (formerly Sebertia acuminata ) by Tanguy Jaffré et al. described. This tree species, endemic to New Caledonia, accumulates 20-25% nickel in its milky sap (latex), which turns it blue-green in color.

Compared to non-hyperaccumulating species, the metals are absorbed faster by the roots, transported faster in shoots and stored in certain parts of the plant. The ability to hyperaccumulate toxic metals could be traced back to different gene expressions as well as gene regulation of such genes , which are also present in plants of normal locations; So it is not about a completely new metabolic pathway, but about increasing the efficiency of an existing one. More than 500 species of flowering plants with the ability to hyperaccumulate metals in their tissues have been identified.

Hyperaccumulating plants are used specifically to extract metals from contaminated soil ( phytoremediation ). In this way, disturbed locations - mostly due to contaminated sites after industrial or mining use - can be rehabilitated and made usable again. There are also projects to extract metals from soils by means of so-called phytomining , where conventional mining methods are no longer economical. In this way, for example, nickel is successfully extracted from serpentine soils in Albania .

The evolutionary advantage of metal hyperaccumulation could be that concentrated heavy metals in leaves deter herbivorous animals due to their toxicity . The poisonous leaf litter also accumulates heavy metals on the soil surface and would reduce the competitive pressure from less tolerant plants, as they make it impossible for them to thrive.

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Individual evidence

  1. ↑ a b c Nicoletta Rascio, Navari-Izzo, Flavia: Heavy metal hyperaccumulating plants: How and why do they do it? And what makes them so interesting? . In: Plant Science . 180, No. 2, February 1, 2011, pp. 169-181. doi : 10.1016 / j.plantsci.2010.08.016 . PMID 21421358 .
  2. ↑ Tanguy Jaffré, Roger D. Reeves, Alan JM Baker, Henk Schat, Antony Van Der Ent: The discovery of nickel hyperaccumulation in the New Caledonian tree Pycnandra acuminata 40 years on: an introduction to a Virtual Issue . In: New Phytologist . 2018, p. 397-400 .
  3. ↑ LR Hossner, Löppert, RH, Newton, RJ, Szaniszlo, PJ: Literature review: Phytoaccumulation of chromium, uranium, and plutonium in planning systems . In: Amarillo National Resource Center for Plutonium, TX (United States) Technical Report . 1998.
  4. ↑ Hemen Sarma: Metal hyperaccumuulation in plants: A Review focusing on phytoremediation technology . In: Journal of Environmental Science and Technology . 4, No. 2, 2011, pp. 118-138. doi : 10.3923 / jest.2011.118.138 .
  5. ↑ A. Bani, Imeri, A., Echevarria, G., Pavlova, D., Reeves, RD, Morel, JL, Sulçe, S .: Nickel hyperaccumulation in the serpentine flora of Albania . In: Fresenius Environmental Bulletin, 22 (6), pp. 1792-1801 . 2013.