Genetic transformation has been used to introduce various genes, coding for accumulation of osmoprotectants � proline or fructan in commercially grown tobacco cultivars in order to improve the abiotic stress tolerance. Various approaches, including screening for resistance to antibiotics, PCR and freezing stress were used to select valuable transgenic lines. Southern blot analysis showed that they contained one to three copies of the integrated genes. The number of genetic loci was estimated by segregation in T1 progeny and stable transgenic lines were selected in T2 progeny