Metals and Metalloid Transport, Tolerance, Detoxification and Homeostasis Strategies in Plants

Metals and metalloids, added to the hydrosphere and lithosphere largely through diverse anthropogenic activities, constitute one of the major environmental contaminants that restrict plant productivity. Their prolonged persistence in the environment, coupled with bio-enrichment of food chains, is resulting in a risk to human health. Plants inherently contain homeostatic pathways to maintain the required level of essential metal ions in different cellular compartments. The essential module of metal homeostasis involves uptake and transport, chelation and sequestration processes. Thus, transporters are key players from the entry of elements to their cellular and intracellular distribution in plants. The study of their mechanism, regulation and spatial nature assumes great significance to plants. Plant genomes encode members of various metal transporter families with substrate specificities, temporal and spatial expression patterns, and cellular localization to regulate metal translocation throughout the plant. Toxic metal(loid)s generally are taken up into plant cells at the expense of essential inorganic ions on account of similar properties and sharing the same transporter network. In response to metal(loid)-mediated stress, complex signal transduction networks are activated which are characterized by synthesis of stress related proteins, signalling molecules, and activation of specific metal-responsive genes as well as enhanced synthesis of chelating agents such as phytochelatins and metallothionins. Additionally, metal(loid) stress leads to redox imbalance, which is controlled by the modulation of antioxidant system. Root-microbe interaction has also been reported to plays a significant role in availability as well as absorption of metal(loids) in plants. In addition supplementation of, nutrients those compete with metal(loids), plant growth regulators and signalling molecules, has been helpful in enhancing the tolerance of plants.

Omics (genomics, transcriptomics, proteomics and metabolomics) investigations are increasingly being used by various groups to explore molecular responses in the plants due to metal(lloid) stress. These studies have led to identification of a number of genes as potential candidates to develop strategies for phytoremediation as well as stress tolerance through biotechnological approaches. Multiple interaction, such as, of plants/lower plant with metal(loid) along with abiotic (Fe, S, Se, N, P etc. and signalling molecules such as nitric oxide, salicylic acid etc.) and biotic (microbes) components has also been a matter of extensive investigation.

This Research Topic will provide recent developments in the area of plant metal(loid) interactions, transport and detoxification, responses at omics level, as well as genetic manipulations for enhanced phytoremediation potential and developing low metal(loid) safe crops. We welcome the following article types: original research, theories and opinions, updates, mini reviews or reviews. Topics will be highlighted by researchers using diverse approaches for deciphering metal(loid) toxicity and tolerance involving homeostatic mechanisms in plants including lower plants (algae, fungi, lichens etc), and interaction of metal(loid) with other stresses.