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Calcium supply effects on wheat cultivars differing in salt resistance with special reference to leaf cytosol ion homeostasis

Authors

  • Sherif H. Morgan,

    1. Institute for Plant Nutrition and Soil Science, Christian Albrechts University, Kiel, Germany
    2. Plant Physiology Section, Plant Botany Department, Faculty of Agriculture, Cairo University, Giza, Egypt
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  • Sylvia Lindberg,

    Corresponding author
    1. Department of Botany, Stockholm University, Stockholm, Sweden
    • Institute for Plant Nutrition and Soil Science, Christian Albrechts University, Kiel, Germany
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  • Karl H. Mühling

    1. Institute for Plant Nutrition and Soil Science, Christian Albrechts University, Kiel, Germany
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Correspondence

Corresponding author,

e-mail: sylvia.Lindberg@su.se

Abstract

Salinity causes changes in cytosolic Ca2+, [Ca2+]cyt, Na+, [Na+]cyt and pH, pHcyt, which induce specific reactions and signals. Reactions causing a rebalancing of the physiological homeostasis of the cytosol could result in plant resistance and growth. Two wheat cultivars, Triticum aestivum, Seds1 and Vinjett, were grown in nutrient solution for 7 days under moderate salinity (0 and 50 mM NaCl) with and without extra addition of 5 mM CaSO4 to investigate the seedling-ion homeostasis under salinity. In the leaf protoplasts [Ca2+]cyt, [Na+]cyt and pHcyt were detected using acetoxymethyl esters of the ion-specific dyes, Fura 2, SBFI and BCECF, respectively, and fluorescence microscopy. In addition, both cultivars were grown for 3 weeks at 0, 50 and 125 mM NaCl with, or without, extra addition of 5 mM CaSO4 to detect overall Na+ and Ca2+ concentrations in leaves and salinity effects on dry weights. In both cultivars, salinity decreased [Ca2+]cyt, while at extra Ca2+ supplied, [Ca2+]cyt increased. The [Ca2+]cyt increase was accompanied by increase in the overall Ca2+ concentrations in leaves and decrease in the overall Na+ concentration. Moreover, irrespective of Ca2+ treatment under salinity, the cultivars reacted in different ways; [Na+]cyt significantly increased only in cv. Vinjett, while pHcyt increased only in cv. Seds1. Even at rather high total Na+ concentrations, the cytosolic concentrations were kept low in both cultivars. It is discussed whether the increase of [Ca2+]cyt and pHcyt can contribute to salt tolerance and if the cytosolic changes are due to changes in overall Ca2+ and Na+ concentrations.

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