Salt tolerance in Lycopersicon species. I. Character definition and changes in gene expression.

Salt tolerance defined in terms of fruit yield under different NaCl concentrations (171.1 and 325.1 mM) is analyzed in 11 lines belonging to: Lycopersicon esculentum, L. cheesmanii, L. chmielewski, L. peruvianum and L. pimpinellifolium. Four L. pimpinellifolium lines and two L. cheesmanii lines tolerated the 171.1mM treatment; the latter species even tolerates 325.1 mM of NaCl. Changes in gene expression induced by salt treatment were also investigated by studying anther and leaf zymograms for L. esculentum and one salt-tolerant L. pimpinellifolium line, and leaf proteinograms for all lines. Changes in leaf PRX and MDH enzymatic systems were detected, mainly in the salt-sensitive genotype (L. esculentum). Four saltrelated peptides from 14 500 to 40 000 daltons were found. A polyclonal antibody raised against one of these peptides (number 2), also binds another peptide, named 2', of much higher molecular weight, present both in control and salt-tolerant L. cheesmanii lines at the end of 171.1 mM treatment. The xero-halophyte shrub Atriplex halimus also showed a likely 2'-homologous peptide with this treatment, while its counterpart C3 species A. triangularis did not.