Chloride: essential micronutrient and multifunctional beneficial ion

Area of Science:

• Plant Physiology
• Environmental Science
• Biochemistry

Background:

• Chloride (Cl−) is an essential micronutrient for oxygenic photolithotrophs, crucial for global primary productivity.
• Many plants, including terrestrial and freshwater glycophytes, encounter environments with Cl− concentrations exceeding nutritional needs but below toxic levels.
• Intracellular Cl− plays key roles in cell turgor, volume regulation, and nastic movements, and is involved in action potentials and ion currents in various plant cells.

Purpose of the Study:

• To investigate the essentiality of chloride (Cl−) in various physiological processes in plants.
• To explore the role of Cl− in regulating cell turgor, volume, and movement.
• To examine the impact of low Cl− concentrations on plant water use efficiency and growth.

Main Methods:

• Literature review on the essentiality of Cl− in photolithotrophs and glycophytes.
• Analysis of Cl− roles in cell turgor, volume regulation, and nastic movements.
• Examination of Cl− involvement in action potentials and ion currents.
• Review of studies on Cl− effects on water use efficiency and leaf area in *Nicotiana tabacum*.

Main Results:

• Chloride (Cl−) is confirmed as an essential micronutrient for oxygenic photolithotrophs, impacting global primary productivity.
• Intracellular Cl− is integral to cell turgor, volume regulation, stomatal and pulvinar movements, and action potentials.
• Low concentrations of Cl− (1–5 mol m−3) have been shown to enhance water use efficiency, growth, and leaf area in *Nicotiana tabacum*.

Conclusions:

• Further research is needed to fully elucidate the essentiality of Cl− in diverse plant physiological processes.
• Chloride (Cl−) has significant implications for plant adaptation to saline environments and overall productivity.
• The findings suggest potential applications of Cl− in improving crop water use efficiency and growth.