Application of nickel hyperaccumulating plants in natural phytoextraction: the Alyssum L. genus

Abstract

Application of nickel hyperaccumulating plants in natural phytoextraction: the Alyssum L. genus.

Metallophytes have evolved biological mechanisms allowing them to survive on metal-rich soils, either of natural (serpentine or ultramafic soils) or anthropogenic origin. Most metallophytes achieve tolerance by physiologically restricting the entry of metals into the root and/or transport to the shoot. A few species, however, have extremely specialized mechanisms enabling them to accumulate, and even "hyperaccumulate" metals (such as Cd, Co, Ni and Zn) in their shoots at concentrations that can exceed 2% of their dry weight: the so-called "hyperaccumulators". There are many more hyperaccumulators of Ni than of any other metal; a vast number are members of the Brassicaceae family, of which most are represented within the genus Alyssum L. Phytoextraction employs these plants to extract soil metals into plant shoots for recycling and less expensive disposal, offering an economic strategy to decontaminate polluted soils. One challenge of adapting hyperaccumulators to practical phytoextraction is the small size and biomass of many of these species. Optimizing soil management practices to increase plant biomass and metal accumulation, and the development of plant breeding programmes for improved hyperaccumulator cultivars, will be crucial in the development of this technique.