## 3 Results
### Plant Biomass after Drought Stress  
After the drought stress treatment, all plants were irrigated. Five days after re-watering, the transgenic wheat lines maintained higher fresh biomass compared to the NT plants (Figure 4a). The wheat plants from the rd-1B and rd-1C lines were taller compared to the 35S transgenic plants and NT plants (Figure 4a). Even when the plants were irrigated after the treatment, the differences in plant height remained until the end of the life cycle of the plants (Figure 4b). Ten days after re-watering, the aerial biomass was measured in terms of dry weight.  
When the wheat plants reached their maturity stage, the aerial biomass was collected, oven-dried, and weighed. The NT plants, as well as the 35S and rd-1C lines, had a reduction (\(p\leq 0.05\)) in the aerial biomass due to drought stress, compared to non-stressed plants (Figure 5a). The aerial biomass in the rd-1B line was also reduced, although this reduction was not statistically significant (Figure 5a). The reduction in the areal biomass of the plants under drought stress was greater in the NT plants compared to the transformed plants (Figure 5a).  
Spikes from mature plants were threshed to measure the total grain weight produced per plant to analyze the effect of drought on the grain yield. A reduction in grain weight because of drought stress was observed in plants from all three transgenic lines and in the NT plants. Furthermore, the NT plants showed the lowest yield under drought stress compared to the transgenic plants (Figure 5b). The decrease in the weight of the grains was statistically significant in the NT plants compared to the transformed ones (Figure 5b).  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Sugar** & & & **Drought (d)** & \\ \hline
**Sucrose** & & & & \\ (\(\mu\)g g\({}^{-1}\) DW) & 0 & 2 & 4 & 6 & 8 \\ \hline NT & \(19.3\pm 1.0\) d & \(21.3\pm 0.8\) d & \(32.9\pm 0.4\) c & \(61.6\pm 1.1\) a & \(37.3\pm 0.5\) b \\ \hline
35S & \(31.4\pm 0.5\) a & \(11.2\pm 0.1\) c & \(6.7\pm 0.04\) e & \(8.4\pm 0.1\) d & \(14.0\pm 0.2\) b \\ \hline rd-1B & \(22.0\pm 0.5\) b & \(23.9\pm 0.1\) a & \(23.7\pm 0.3\) a & \(13.7\pm 0.3\) c & \(13.7\pm 0.01\) c \\ \hline rd-1C & \(10.8\pm 0.04\) e & \(27.3\pm 0.5\) b & \(18.6\pm 0.01\) c & \(30.9\pm 0.5\) a & \(16.6\pm 0.02\) d \\ \hline
**Trehalose** & & & & \\ (\(\mu\)g g\({}^{-1}\) DW) & & & & \\ \hline NT & \(56.8\pm 0.4\) e & \(88.4\pm 1.9\) d & \(146.2\pm 5.2\) b & \(163.9\pm 1.2\) a & \(106.5\pm 0.1\) c \\ \hline
35S & \(108.5\pm 1.6\) b & \(75.2\pm 0.3\) c & \(47.9\pm 0.3\) e & \(115.5\pm 0.7\) a & \(60.7\pm 1.4\) d \\ \hline rd-1B & \(60.9\pm 1.3\) d & \(74.9\pm 0.7\) c & \(92.2\pm 1.0\) a & \(82.8\pm 0.1\) b & \(92.2\pm 0.6\) a \\ \hline rd-1C & \(76.4\pm 1.5\) b & \(66.8\pm 1.5\) c & \(69.9\pm 0.1\) c & \(76.1\pm 0.8\) b & \(97.9\pm 0.4\) a \\ \hline \hline \end{tabular} Data show mean \(\pm\) standard error (\(n=3\)). Letters indicate significant differences during days of drought (\(p\leq 0.05\)).  
\end{table}
Table 2: Content of sucrose and trehalose in wheat plants under drought stress.  
Figure 4: Comparison of plant biomass between non-transformed (NT) and transgenic wheat lines: (**a**) five days after re-watering (61 days post-germination) and (**b**) at the maturity stage.  
Figure 5: Effect of drought stress on final biomass of wheat plants: (**a**) aerial dry biomass; (**b**) total grain weight per plant. Values are mean \(\pm\) SE (\(n=5\)). Student’s \(t\)-test at \(p<0.05\) (\({}^{\star}\)) was used to evaluate significant variations between non-stressed and stressed plants.