Mitochondrial Acid Phosphatase and Adenosine Triphosphatase Activities in Germinating Rice Seeds Following NaCl Salinity Stress

Effect of NaCI salinity on activities of mitochondrial acid phosphatase and adenosine triphosphatase (ATPase) were studied in germinating rice (Oryxa sativa L.) seeds differing in salt tolerance. In salt tolerant cvs. CSR-1 and CSR-3 mitochondrial acid phosphatase activity increased in vivo in endosperms and embryoaxes with increasing levels of salinity whereas in salt sensitive cvs. Ratna and Jaya the activity of the enzyme decreased under salinisation. Mitochondrial ATPase activity increased in embryoaxes of germinating salt tolerant rice seeds under salinisation whereas in sensitive cultivars salinity caused decrease in enzyme activity in both endosperms and embryoaxes, NaCl when incorporated in the reaction medium caused inhibition in acid phosphatase activity in vitro in the both sets of cultivars. KC1, Na₂SO₄ and MgSO₄ stimulated acid phosphatase activity in vitro whereas CaCl₂ caused inhibition in enzyme activity. Results suggest varying behaviours of phosphorolytic enzymes in the two sets of rice cultivars differing in salt tolerance and that salt tolerance ability is associated with increased activities of these enzymes under salinisation.