Salicylic acid produced by isochorismate synthase and isochorismate pyruvate lyase in various parts of constitutive salicylic acid producing tobacco plants

Abstract

Salicylic acid production in roots, stems, young leaves, medium leaves and old leaves of constitutive salicylic acid producing (CSA) tobacco plants was tested. In protein extracts of CSA-tobacco plants, the formation of isochorismate and of salicylic acid (SA) were measured to determine isochorismate synthase (ICS) and isochorismate pyruvate lyase (IPL) activity. The highest production of isochorismate and SA in vitro were produced by protein extracts of the young leaves of CSA-tobacco plants. The isochorismate and SA productions in vitro by protein extracts and the accumulation of SA and SA-glucoside in CSA-tobacco plants varied among the tested lines and within one line. The accumulation of SA in vivo is determined by the activity of IPL.