Amino acids regulate salinity-induced potassium efflux in barley root epidermis
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The amino acid content increases substantially in salt-stressed plants. The physiological relevance of this phenomenon remains largely unknown. Using the MIFE ion flux measuring technique, we studied the effects of physiologically relevant concentrations of 26 amino acids on NaCl-induced K+ flux from barley root epidermis. We show that 21 (of 26) amino acids caused a significant mitigation of the NaCl-induced K+ efflux, while valine and ornithine substantially enhanced the detrimental effects of salinity on K+ homeostasis. Our results suggest that physiologically relevant concentrations of free amino acids might contribute to plant adaptive responses to salinity by regulating K+ transport across the plasma membrane, thus enabling maintenance of an optimal K+/Na+ ratio as opposed to being merely a symptom of plant damage by stress. Investigating the specific mechanisms of such amelioration remains a key issue for future studies.
KeywordsAmino acids Barley Membrane Potassium homeostasis Stress Adaptation
Microelectrode ion flux
This work was supported by ARC Discovery grant (DP0449856) to S. Shabala.
- Bush DR (1999) Amino acid transport. In: Singh BK (ed) Plant amino acids. biochemistry and biotechnology. Marcel Dekker, New York, pp 305–318Google Scholar
- Curl EA, Truelove B (1986) The Rhizosphere. Springer, Berlin Heidelberg New YorkGoogle Scholar
- Dubey RS, Rani M (1990) Influence of NaCl salinity on the behavior of protease, aminopeptidase and carboxypeptidase in rice seedlings in relation to salt tolerance. Aust J Plant Physiol 17:215–221Google Scholar
- Kavi Kishor PBK, Sangam S, Amrutha RN, Laxmi PS, Naidu KR, Rao K, Rao S, Reddy KJ, Theriappan P, Sreenivaslu N (2005) Regulation of proline biosynthesis, degradation, uptake and transport in higher plants: its implications in plant growth and abiotic stress tolerance. Curr Sci 88:424–438Google Scholar
- Nakamura Y, Kasamo K, Shimosato N, Sakata M, Ohta E (1992) Stimulation of the extrusion of protons and H+-ATPase activities with the decline in pyrophosphatase activity of the tonoplast in intact mung bean toots under high-NaCl stress and its relation to external levels of Ca2+ ions. Plant Cell Physiol 33:139–149 Google Scholar
- Paleg LG, Douglas TJ, Vandaal A, Keech DB (1981) Proline, betaine and other organic solutes protect enzymes against heat inactivation. Aust J Plant Physiol 8:107–114Google Scholar
- Rhodes D, Verslues PE, Sharp RE (1999) Role of amino acids in abiotic stress resistance. In: Singh B (eds) Plant amino acids. Biochemistry and biotechnology. Marcel Dekker, New York, pp 319–356Google Scholar
- Verma DPS, Zhang C-S (1999) Regulation of proline and arginine biosynthesis in plants. In: Singh BK (ed) Plant amino acids. Biochemistry and biotechnology. Marcel Dekker, New York, pp 249–266Google Scholar