Understanding molecular mechanisms for improving phytoremediation of heavy metal-contaminated soils

Abstract

Heavy metal pollution of soil is a significant environmental problem with a negative potential impact on human health and agriculture. Rhizosphere, as an important interface of soil and plants, plays a significant role in phytoremediation of contaminated soil by heavy metals, in which, microbial populations are known to affect heavy metal mobility and availability to the plant through release of chelating agents, acidification, phosphate solubilization and redox changes, and therefore, have potential to enhance phytoremediation processes. Phytoremediation strategies with appropriate heavy metal-adapted rhizobacteria or mycorrhizas have received more and more attention. In addition, some plants possess a range of potential mechanisms that may be involved in the detoxification of heavy metals, and they manage to survive under metal stresses. High tolerance to heavy metal toxicity could rely either on reduced uptake or increased plant internal sequestration, which is manifested by an interaction between a genotype and its environment.A coordinated network of molecular processes provides plants with multiple metal-detoxifying mechanisms and repair capabilities. The growing application of molecular genetic technologies has led to an increased understanding of mechanisms of heavy metal tolerance/accumulation in plants and, subsequently, many transgenic plants with increased heavy metal resistance, as well as increased uptake of heavy metals, have been developed for the purpose of phytoremediation. This article reviews advantages, possible mechanisms, current status and future direction of phytoremediation for heavy-metal-contaminated soils.

Physiological adaptive mechanisms of plants grown in saline soil and implications for sustainable saline agriculture in coastal zone

“…Enhancing plant salt tolerance is a crucial step for culturing crops in saline land, and there are three methods-conventional breeding program, gene engineering method and ordinary physiological methods. Due to the complexity of functional genes in response to salt stress, conventional breeding program is relatively hard to be executed effectively (Flowers 2004;Shabala and Cuin 2008;Shao et al 2009Shao et al , 2010. Although many studies have announced that salt tolerance was enhanced in transgenic plants (Begcy et al 2011;Hao et al 2011;Jacobs et al 2011;Rahnama et al 2011;Wei et al 2011), the results are obtained under abnormal growth condition and not tested in the field.…”

Reactive Oxygen in Abiotic Stress Perception - From Genes to Proteins

“…Indeed, vacuolar compartmentalization is considered as the major tolerance mechanism allowing HM accumulation in plants, mainly in the vacuoles of root cells. However, it has been demonstrated for some HM hyperaccumulator species, that shoots can www.intechopen.com contain higher HM levels than roots (Hong-Bo et al, 2010). It is possible that chelators act as HM sensors and that the modification of these HM sensors/scavengers might be recognized by other proteins to decipher the information.…”

“…A variety of molecules are able to chelate HM, including both low molecular weight molecules such as organic acids, amino acids, peptides, as well as proteins, such as metallothioneins or phytochelatins (PC). After chelation, HM are transported and further sequestered in the vacuole (Hong-Bo et al, 2010). Indeed, vacuolar compartmentalization is considered as the major tolerance mechanism allowing HM accumulation in plants, mainly in the vacuoles of root cells.…”

Grafting as an Alternate Tool for Biotic and Abiotic Tolerance with Improved Growth and Production of Solanaceous Vegetables: Challenges and Scopes in India

“…The increasing levels of heavy metals in agricultural land are gradually becoming an serious threat not only for crop plants, but also for the environment and human health Gratão et al, 2005;Clemens, 2006;Hong-Bo et al, 2010;Raskin et al, 1997). Non judicial use of large amounts of chemicals, irrigation with the reclaimed wastewater, the application of contaminated soil amendments, sewage sludge and other anthropogenic activities have dramatically increased the concentrations of several nutrient ions as well as heavy metals in the soils (Guo et al, 2004;He et al, 2005;Yu et al, 2005).…”