Expression of trehalose-6-phosphate synthase gene from Arabidopsis thaliana in transgenic tobacco: a strategy to increase temperature stress tolerance

Background

Genetic engineering of plants towards osmoprotectant accumulation is gaining increased importance within the broad context of abiotic stress tolerance [1]. An enzyme, trehalose-6-phosphate synthase, is believed to play a key role in the synthesis of the disaccharide trehalose and hence on the improvement of abiotic stress tolerance [2]. We used Agrobacterium to transform tobacco plants to express the trehalose-6-phosphate synthase gene from Arabidopsis thaliana, under the control of CaMV 35S promoter and using the vector pGreen 0229 [3]. Transgenic T2 plants were evaluated for gene expression by northern and western blots. Seeds were sown in media germinated at: 15, 25 and 35°C for evaluating germination rates under high and low temperatures.

Results

Three of the transgenic lines obtained (B5A, B5H and B1F) have distinct levels of gene expression: B5H and B5A are high expressing lines while B1F is a low expressing one. In non-transgenic controls no expression was detected (Figure 1).

Figure 1

AtTPS1 gene expression analysis in WT and transgenic tobacco lines. A – Northern blot B – Western blot. In both cases, no AtTPS1 protein production was detected in control wild type plants while transgenic lines showed accumulation of AtTPS1 transcripts and enzyme. WT – Wild Type; B5A, B5H and B1F – Transgenic line. MW – Molecular weight markers (kDa).

Transgenic lines were shown to have significantly higher germination rates under low and high temperatures (respectively, 15 and 35°C) than wild type plants (Table 1).

Table 1 Germination rates (Number of seeds germinated per 100 seeds placed on germination medium) of three transgenic lines at three different temperatures.

Conclusion

Our results demonstrate that transgenic plants accumulating trehalose-6-phosphate synthase have an altered phenotype that includes temperature stress tolerance upon germination. We suggest that AtTPS1 can be used to engineer important crop plants such as maize, wheat or rice to withstand different environmental stresses.