Ectopic expression of transcription factor AtDREB1A confers increased tolerance against drought stress in tobacco (Nicotiana tabaccum)

Drought is a key limiting factor for growth of plant and crop production. In an effort to produce drought tolerant tobacco, an expression cassette comprising the Arabidopsis DREB1A cDNA under the Figwort Mosaic Virus (FMV) and Rice SalT promoters were transformed into tobacco via Agrobacterium mediated transformation. FMV is a strong and constitutive promoter and SalT is a stress inducible promoter that can be used for enhancing expression of AtDREB1A gene in tobacco. PCR was used to confirm the putative transgenic T₀ plants and copy number was determined by Southern blot hybridization. RT-PCR confirmed the gene expression in transgenic tobacco lines. The selected transgenes with one copy number were subjected to osmotic stress. Seed germination results showed that transgenic seeds were able to germinate on 300 mM mannitol while control seeds were unable to germinate. Transgenic plants exhibited higher drought tolerance and produced more seeds than control plants when water was withheld for 10 days. Various physiological tests revealed higher drought stress tolerance in transgenic plants than their wild type counterparts. The current study showed that overexpression of AtDREB1A gene under FMV and SalT promoters increases drought tolerance in transgenic tobacco and offers applications in developing drought tolerant crops.