Characterization of salt tolerant plants derived from a Lycopersicon esculentum Mill. somaclone

Plants were regenerated from cotyledon explants of Lycopersicon esculentum Mill., placed on a control medium and on medium added with a glucose derive d, non trophic compound: 3-O-methyl-D-glucose, used as an osmotic agent. A preliminary test conducted in vitro, allowed us to identify a somaclone (na med C4) which showed three times higher germination rates compared to wild type, in a salt enriched medium. To confirm the tolerance character in vivo and during the different life phases of the plant, young R1 plantlets from this somaclone and wild type plantlets, have been tested with increasing c oncentrations of salt (0, 75, 150, 300 mmol/L sodium chloride). At the end of the treatment, consistent necrosis of leaf and flower organs were eviden t only in wild type plants. Moreover, we observed a strong drop of leaf tur gor in wild type leaves under salt treatment, instead, line C4 plants retai ning the turgor. A highest concentration of sodium was detected in leaf tis sues in wild type plants, compared to line C4 ones, attesting the capacity of C4 line plants to regulate the amount of this toxic ion in leaves. The s ynthesis of organic compounds, proline and total amino acids, was lower in line C4 plants. Polymorphic RAPD fragments in C4 line were identified. Taki ng together all the data, line C4 plants show the ability to tolerate high salinity conditions, compared to wild type, in particular we suggest that t hese planes are able to regulate differently the amount of sodium in tissue s.