Estratégias de tolerância da fitorremediação de metais pesados em plantas-modelo: um estudo de caso em espécies do gênero botânico Brassica

Abstract

The increase in soil contamination by heavy metals (HMs) such as cadmium (Cd), chromium (Cr), mercury (Hg), arsenic (As), lead (Pb), nickel (Ni), and zinc (Zn), has generated major environmental concerns, mainly due to the non-biodegradability characteristic of these HMs, which makes them remain in the environment for long periods. Some remediation techniques for contaminated soils are reported in the literature, among them, phytoremediation stands out, a technology that uses plants capable of stabilizing or remediating environmental contamination through contaminant absorption and accumulation strategies. Some plants species are more tolerant to the toxic effects of HMs, such as plants belonging to the botanical genus Brassica. Some HMs, such as Zn and Ni, are essential to plants, however high concentrations of these HMs or other non-essential ones, such as Cd, can cause cell damage, osmoregulation, in the photosynthetic metabolism, and the gas exchange of plants. Brassica species, however, have an efficient enzymatic and non-enzymatic defense mechanism against the stress generated by these contaminants. The literature reports that some agronomic management techniques such as the use of plant growth regulators, plant growth promoters, chelating and acidifying agents, in addition to the selection of more tolerant cultivars and the use of genetic engineering, can help in the uptake and tolerance of HMs by Brassica plants. Therefore, species of the botanical genus Brassica are an interesting model for studies in the field of phytoremediation and, therefore, we chose to write this monograph as a scientific review article, based on the continuous update of what is most current and promising in the field literature on phytoremediation of HMs by Brassica species.