Phosphatase induction under stress conditions in wheat

Abstract

The effects of phosphorus deficiency and osmotic (NaCl or polyethylene glycol, PEG) stresses on phosphatase activity were compared in the soluble fraction of shoots of wheat cv. Kharchia, a known salt tolerant cultivar. Phosphatase activity increased under P deficiency and water stress conditions. Phosphatase activities in the supernatant were assayed using ATP, Na-pyrophosphate and P-nitro-phenylphosphate as substrates at varying pH. Changes in phosphatase isoenzyme patterns under different stress conditions were followed by phosphocellulose column chromatography. Two main phosphatase peaks were found in control plants. Both were present under different stress conditions, but in different proportions. Changes in relative activities towards different substrates were also evident. It is suggested that the phosphatase isoenzyme pattern differences found under P deficiency, osmotic and salt stresses, explain the differences in substrate specificities and the specific activities of the supernatants. Mg2+-activated alkaline phosphatase activity, specific for the shoot, decreased under all stress conditions, and did not bind to the P-11 column, providing an easy separation from the acid phosphatases.