Composition of xylem and phloem exudates in relation to the salt-toleranceof domestic and wild tomato species

Plants of Lycopersicon esculentum cv. Volgogradskij (Le) and L. pennellii a ccession PE-47 (Lp) were cultivated for 22 days under control and saline (1 00 mmol/L NaCl) conditions. Besides growth parameters and leaf water conten t, toxic ions (Na+, Cl-), major nutrients (K+, Ca2+, Mg2+ and PO43-) and as similates (carbohydrates and amino acids) were determined weekly in xylem a nd phloem exudates. Salinity reduced plant dry weight by 55% and 29% in Le and Lp, respectively while a 46% increase in the root biomass was found in the latter. An earlier and higher Na+ and Cl- accumulation in the xylem and a greater Na+ retranslocation through phloem was found in Lp. The better n utritional status found in the xylem of the salinized plants of the wild sp ecies at the end of the salinization period seems also to be linked to phlo emxylem retranslocation. Thereafter, a more rapid and higher transport of c arbohydrates and amino acids from roots to shoot through xylem was found in Lp than in Le under salinity. The implication of these parameters in the s alt-tolerance of tomato has been discussed.