Abiotic stresses such as drought and salinity are the most considerable cause of crop productivity decrease in agriculture. Genetic engineering can improve crop tolerance to abiotic stresses by many ways. Mannitol is one of plant osmoprotectants to cope with osmotic stress. In the previous study, we developed transgenic Canola (Brassica napus L.) using bacterial mtlD gene. Here, salt stress tolerance of transgenic (+mtlD) and non-transgenic (-mtlD canola plants studied on seed germination stages. The sterilized transgenic and non-transgenic seeds were cultured on MS media (pH 5.8) at different concentrations of NaCl (0 250 300, 350, 400 and 450 mM). HPLC analysis results showed that transgenic plants accumulate mannitol on average of 0.0440 mg/gDW, whereas wild-type plants did not accumulate any mannitol. However, transgenic seeds germinated at 350 mM NaCl, non-transgenic plants
germinated not more than 250 mM of NaCl. Therefore, we demonstrated that the mtlD gene was expressed in transgeniccanola plants, resulting in mannitol accumulationand improved salt tolerance in transgenic seeds.