NaCl Stress-Induced Organic Solute Changes on Leaves and Calli of Lycopersicon esculentum, L. pennellii and their Interspecific Hybrid

Abstract

A comparative study between leaves of whole plants and calli from leaf was carried out in Lycopersicon exculentum (L.) Mill., L. pennellii (Correll) D'Arcy and their interspecific hybrid with the objective to obtain knowledge of the NaCl stress-induced changes in the total soluble sugars, organic acids, free amino acids and soluble proteins. Similar growth responses to salinity were found in leaf and calli of both parents and their hybrid, because leaf dry weight and the relative growth rate of calli increased in L. pennellii and decreased in L. esculentum and the hybrid at 70 mM NaCl with respect to controls. Total soluble sugar and organic acid contents were much higher in calli than in leaves. Sugars decreased with salinity in calli of L. pennellii and increased significantly in L. esculentum and the hybrid. However, these solutes are not related to salt tolerance in the leaves of whole plants. In general, total organic acids decreased with salinity in both parents and their hybrid at both organizational levels. An increase in total free amino acid contents with salinity was observed at both organizational levels in L. esculentum and the hybrid, while it was only found in leaves of L. pennellii , although to a lower degree. These increases were mainly due to proline and GABA in salt-sensitive L. esculentum and the hybrid, and Asn + Glu in L. pennellii . On the basis of these results, proline and GABA contents may be useful as possible salt-injury sensors, in both leaf and calli from leaf. Moreover, the relation between sugar content and salt-tolerance degree in calli indicates that leaf-cell culture is a good method to study the implication of sugar metabolism in salt-tolerance responses.