Genetic improvement in tomato (Solanum lycopersicum) against salt stress

Salinity and drought are the two major abiotic stresses that affect the quality and quantity of tomato. The dehydration response transcription element binding factor (DREB) gene enhances tolerance in plants against salinity. The present study was conducted to transformed DREB1A gene through Agrobacterium in tomato cultivar Roma against salt stresses. A binary vector containing DREB1A gene under the control of inducible promoter Lip 9 along with hygromycin screening marker was used. The few major factors which directly affect transformation efficiency were optimized such as acetosyringone levels, cefotaxime concentrations, pre-selection time period and hygromycin levels. Four different concentrations (50, 100, 150 and 200 mM) of NaCl were applied on both transgenic and non transgenic plants. The addition of 200 mu M acetosyringone in co-cultivation media, 200 mg/L cefotaxime in pre-culturing media and 25 mg/L hygromycin concentration significantly increased transformation efficiency. Maximum transformation efficiency 16.6% was obtained in tomato cultivar Roma. The transgenic plants were confirmed with PCR and the expected band size similar to 630 bp was amplified. The transgene express in transgenic tomatoes was confirmed by reverse transcriptase-polymerase chain reaction (RT-PCR). The resulted transgenic plants showed enhanced tolerance against high salt concentration (200 mM) while the non transgenic plants showed the symptoms of wilting and eventually die at that concentration. The DREB1A gene was successfully transformed into local tomato cultivar Roma. The resulted transgenic tomato cultivar Roma will be recommended against extreme salt stresses.