Physiological Roles of Organic Acids in Alkali-Tolerance of the Alkali-Tolerant Halophyte Chloris virgata
- Chunwu Yanga,
- Weiqing Guoa and
- Decheng Shi *a
Seedlings of Chloris virgata, an alkali-tolerant halophyte, were stressed with a range of salt stress (molar ratio of NaCl:Na2SO4 = 1:1, 40–200 mM, pH 6.48–6.65) or alkali stress (molar ratio of NaHCO3:Na2CO3 = 1:1, 40–200 mM, pH 9.93–9.97). Contents of organic acids (OAs) and inorganic ions were measured, and the OAs in secretions analyzed, to probe physiological roles of OAs in alkali-tolerance. Under alkali stress, Na+ sharply increased, and NO3 − and H2PO4 − decreased in shoots, which caused a severe deficit of negative charge. This deficit was greatly remedied by OA. We propose that OA metabolic regulation might play an important role in the intracellular ion balance of C. virgata. Chloris virgata accumulated mainly malate and citrate in shoots. However, in roots, synthesis, and secretions of acetate, oxalate, formate, and lactate were significantly stimulated, especially acetate. This indicated that roots and shoots might differ in adjustment mechanisms for OA metabolism, and that OA secretion may be important for pH adjustment outside the roots.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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