About this Research Topic
Ion homeostasis is a dynamic process and a fundamental requirement for all organisms. Many different minerals are required for essential biochemical processes, but accumulation of these elements may be toxic. Thus, all living organisms have developed efficient systems to acquire and store these elements and maintain their cytosolic and organellar concentrations within a specific physiological range that allow for normal development. This requirement has determined the establishment of evolutionary conserved, robust molecular mechanisms to maintain these homeostatic concentrations and avoid toxicity, while at the same time, permitting dynamic responses to environmental changes.
In plants, most membranes are energized by gradients of protons created by ATPases. Therefore, maintaining the pH homeostasis consumes about 50% of the ATP generated by glycolysis. This energetically costly gradient is used for the uptake of the required ions such as potassium, magnesium or calcium, and to extrude toxic ions, such as sodium or heavy metals. In addition, each ion must be maintained within a very narrow range of concentrations that varies with the subcellular location. Ion concentrations in the cytoplasm can range from about 150 mM for potassium to less than 1 microM for calcium, independently of the soil concentration. Concomitantly, the plant cell needs a complicated network of transporters and regulators to maintain homeostasis and to drive the changes required to respond to growth or stress signaling. Ion homeostasis determines pivotal functions for plant biology, such as the compensation of the negative charges of macromolecules, maintenance of electroneutrality, and establishment of cell turgor and volume. Also, a proper ion potential in the internal media or in the subcellular organelles is required for enzyme activity and other essential functions like protein synthesis. Ions are also essential components of biomolecules, such as chlorophyll or hemoglobin, and they play a key role at the whole plant level, by contributing to vital processes such as stomatal aperture which controls transpirational water loss, plant desiccation and cell elongation.
This Research Topic focuses on the most recent advances in the maintenance and regulation of ion homeostasis, with a special focus on the identification and characterization of new components participating in ion homeostasis. We therefore welcome contributions related to:
- Potassium and sodium transport.
- Salt or heavy metal stress.
- Calcium and magnesium homeostasis.
- Hormone regulation of ion transport or homeostasis.
- Ion fluxes and cell guard regulation or cell elongation.
- Systems biology approaches to ion homeostasis.
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