EFFECTS OF PHLORHIZIN AND P-CHLOROMERCURIBENZENESULFONIC ACID ON SUCROSE AND PROLINE ACCUMULATION IN DETACHED TOMATO LEAVES SUBMITTED TO NACL AND OSMOTIC STRESSES

Proline accumulation was induced in detached tomato leaves in the absence of any saline or osmotic stress. An osmotically low trehalose concentration in the incubation medium (25 mM) or 10 and 50 mM sucrose in the presence of the inhibitors of the sucrose carrier of plasmalemma (phlorizin and p-chloromercuribenzenesulfonic acid) were used for this induction. Moreover, the proline accumulation induced by saline or osmotic stress (300 mM NaCl, 800 mM sucrose or PEG 380 g kg(-1)) was modified by the different treatments acting on the sucrose content. A positive correlation was found between proline and sucrose accumulation and water content in the tissue under saline stress (r = 0.9288 and r = 0.9348, respectively), while this correlation was only positive with proline (r = 0.8856) under PEG conditions. Therefore, an important correlation was found between proline and sucrose accumulation under saline stress (r = 0.9819). The implication of sucrose in the osmotic adjustment and its accumulation in the apoplastic space before phloem loading was discussed in relation to proline accumulation, according to the approach assessed.