ABSTRACT
Transgenic tobacco plants expressing a stress responsive gene BoRS1, isolated from Brassica oleracea var. acephala, under the control of the 35S promoter of the Cauliflower mosaic virus were produced. Some plants were further used to test the effect of high level BoRS1 expression on drought stress resistance. The presence of transgene in putative transgenic plants was confirmed by PCR analysis. Thirty-six among 130 transformants showed amplification of predicted fragment of BoRS1 while no amplification was observed in the control. Some transgenic lines confirmed by PCR analysis were analyzed through semi-quantitative one-step RT-PCR for the expression of BoRS1 gene. Amplification of 1.4 kb cDNA product revealed transcription of BoRS1 gene. Meanwhile, differential intensity of the cDNA band indicated variable expression levels of the transgene among different transformed lines. The water loss of detached leaves from the transgenic plants was slower than that of the control. Transgenic tobaccos and the non-transgenic controls were used for further drought stress experiments by using different concentration of mannitol. The transformants showed higher tolerance to drought stress than non-transgenic plants and different transgenic lines exhibited different tolerance during drought stress. These results showed that the BoRS1 gene probably play role in enhancing the ability to drought stress.