Hyperaccumulators and Biotic Interactions



Plants selected for phytoextraction are chosen for their ability to extract large volumes of pollutants. They are called hyper-accumulator plants, or hyper-accumulators. Common characteristics of hyperaccumulators are often: rapid growth; hardy plants that are easy to plant and maintain; high evapotranspiration capacity (evaporation of water through the leaves); and the ability to transform the contaminants concerned into non-toxic or less toxic products. Among the most commonly used plants are poplars, which combine rapid growth, great climatic adaptation, and the ability to absorb large quantities of water (relative to other species). This last quality allows them to treat larger quantities of dissolved pollutants, as well as limiting the amount of water passing beyond the contaminated area - thus also limiting the spread of contamination.

In 1999 Reeves et al9 listed 320 accumulator species from 43 families. The number is much higher: for example, in 2006 about 300 nickel hyperaccumulators are known. Centres of diversity occur in Cuba (subtropical climate) and New Caledonia (tropical climate). Many of the species studied for metal accumulation are Brassicaceae (temperate and cold climate, northern hemisphere).

Abdelhak El Amrani's research team on the mechanism behind biodiversity at the University of Rennes has worked on several pollutants, in particular the herbicide atrazine. These researchers have discovered a mechanism in plants that allows them to develop even when the concentration of pollution in their soil is normally lethal for an untreated plant. It is the presence of certain simple biodegradable natural compounds, such as exogenous polyamines, that allows plants to tolerate pollutant concentrations 500 times higher than control plants, but also to absorb more pollutants. This treatment leads to changes in the genetic expression of the plants, involving genes known to be involved in the process of resistance to environmental stress. The genetic technique has been patented by the University of Rennes10.

A plant is said to be a hyperaccumulator if it can concentrate the pollutant(s) to a minimum percentage that varies according to the pollutant concerned (e.g. more than 1 mg/g dry matter for nickel, copper, cobalt, chromium or lead; or more than 10 mg g/1 for zinc or manganese11. Most of the 215 hyperaccumulators cited by Baker and Brooks concern nickel. They listed 145 hyperaccumulators for nickel, 26 for cobalt, 24 for copper, 14 for zinc, four for lead, and two for chromium. This accumulation capacity is due to hypertolerance, or phytotolerance: the result of the adaptive evolution of plants to hostile environments over multiple generations. Boyd and Martens 12 list the biotic interactions that can be affected by metal hyperaccumulation:

  1. Protection
  2. Interference with neighbouring plants of different species.
  3. Mutualism
  4. Commensalism
  5. Biofilm


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Keywords

Hyperaccumulator
Hyperaccumulators
Phytodegradation
Phytoextraction
Phytomining
Phytoremediation
Phytoremediative
Phytoremediative Plants
Phytostabilisation
Phytovolatilisation
Rhizofiltration

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DeepDove: Nature Network (2021-09-21). Hyperaccumulator | Hyperaccumulators and Biotic Interactions. Retrieved , from

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This page was last changed on 2021-09-21.