Salinity is among the major threats to agriculture having been the reason for demise of Sumer civilisation and nowadays causing annual economic losses over 10 billion USD. Effects of salinity on plants include 1) osmotic stress, 2) disruption of membrane ion transport, 3) direct toxicity of cytoplasmic sodium ...
Salinity is among the major threats to agriculture having been the reason for demise of Sumer civilisation and nowadays causing annual economic losses over 10 billion USD. Effects of salinity on plants include 1) osmotic stress, 2) disruption of membrane ion transport, 3) direct toxicity of cytoplasmic sodium and chloride at high concentrations and 4) induced oxidative stress. Ion transport is vital in determining salinity tolerance in plants; main crucial points include specific processes of cation and anion transport across plasma membranes of root cells, transport through vacuolar membrane, long distance ion transport via xylem and phloem and also salt exclusion/accumulation by specialised cells. Transport via membranes is mediated by ion channels and transporters, which ensure selective passage of definite ions. Over 1000 genes are predicted to encode membrane proteins in model salt-sensitive plant Arabidopsis, over 100 of them are cation channels and transporters. The molecular and structural diversity of ion channels and transporters is amazing: 1) they differ in number of transmembrane domains, 2) selectivity filters for allowing highly specific transport of definite ions, 3) molecular structures for gating (opening and closing) by changing membrane voltage or by certain chemical compounds, 4) regulation by interacting proteins or chemical modifications (e.g. by phosphorylation/dephosphorylation). Naturally occurring salt-tolerant plants and halophytes provide unique source of traits for tolerance and genes for membrane proteins and their regulators; they could be transferred to agriculturally important crops to increase their tolerance. Attention in the aspect is also attracted by salt-tolerant algae and fungi with ion transporters, channels and pumps potentially unknown for Kingdom Plantae. An alternative approach from synthetic biology is to modify the existing membrane transport proteins or create new ones with desired properties for transforming agricultural crops. Detailed description of distinct ion channels and transporters leading further to involved cellular and whole plant mechanisms is the logical way to understand salinity tolerance. Theoretical and pure scientific aspects aim to protein chemistry, structure-function relations of membrane proteins, systems biology and physiology of stress and ion homeostasis. The focus of contributions is expected to be on the above mentioned questions and perspectives. All types of articles including original research, review, mini review, method, and perspective/opinion/hypothesis are welcomed.
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