Nanoscale copper particles (nano-Cu) are used in many antimicrobial formulations and products for their antimicrobial activity. They may enter deliberately and/or accidentally into terrestrial environments including soils. Being the major 'eco-receptors' of nanoscale particles in the terrestrial ecosystem, soil-microbiota and plants (the soil-plant system) have been used as a model to dissect the potential impact of these particles on the environmental and human health. In the soil-plant system, the plant can be an indirect non-target organism of the soil-associated nano-Cu that may in turn affect plant-based products and their consumers. By all accounts, information pertaining to nano-Cu toxicity and the underlying potential mechanisms in the soil-plant system remains scanty, deficient and little discussed. Therefore, based on some recent reports from (bio)chemical, molecular and genetic studies of nano-Cu versus soil-plant system, this article: (i) overviews the status, chemistry and toxicity of nano-Cu in soil and plants, (ii) discusses critically the poorly understood potential mechanisms of nano-Cu toxicity and tolerance both in soil-microbiota and plants, and (iii) proposes future research directions. It appears from studies hitherto made that the uncontrolled generation and inefficient metabolism of reactive oxygen species through different reactions are the major factors underpinning the overall nano-Cu consequences in both the systems. However, it is not clear whether the nano-Cu or the ion released from it is the cause of the toxicity. We advocate to intensify the multi-approach studies focused at a complete characterization of the nano-Cu, its toxicity (during life cycles of the least-explored soil-microbiota and plants), and behavior in an environmentally relevant terrestrial exposure setting. Such studies may help to obtain a deeper insight into nano-Cu actions and address adequately the nano-Cu-associated safety concerns in the 'soil-plant system'.

Central European Institute of Technology Brno University of Technology Technicka 3058 10 CZ 616 00 Brno Czech Republic

CESAM Centre for Environmental and Marine Studies and Department of Chemistry University of Aveiro 3810 193 Aveiro Portugal

CESAM Centre for Environmental and Marine Studies and Department of Chemistry University of Aveiro 3810 193 Aveiro Portugal; CESAM Centre for Environmental and Marine Studies and Department of Biology University of Aveiro 3810 193 Aveiro Portugal

Department of Botany Faculty of Science Hamdard University New Delhi 110062 India

Department of Botany Plant Physiology and Ecology N P Ogarev Mordovia State University Bolshevistskaja Str 68 Saransk 430005 Russia

Department of Chemistry and Biochemistry Faculty of Agronomy Mendel University in Brno Zemedelska 1 CZ 613 00 Brno Czech Republic; Central European Institute of Technology Brno University of Technology Technicka 3058 10 CZ 616 00 Brno Czech Republic

References provided by Crossref.org

Phytostabilization-Management Strategy for Stabilizing Trace Elements in Contaminated Soils

Nanoparticles based on essential metals and their phytotoxicity