Figure 3.

Growth profile and yield parameters of T₁ generation transgenic tobacco plants overexpressing glyoxalase I (GI), glyoxalase II (GII), or both glyoxalase I and glyoxalase II in double transgenics (GI + II) in zinc-spiked soils. A, Representative image showing relative growth of wild-type and transgenic tobacco plants in soil pots in the continued presence of 5 mm ZnCl₂ for 98 d. B, Total zinc content in various tissues of the glyoxalase transgenic plants (GI, GII, and GI + II) grown under the continued presence of 5 mm ZnCl₂ for 150 d (calculated as percent dry weight of the tissue). In the histogram, each of the transgenic types is indicated by different colored bars as shown. For each determination, roots, old leaf (fourth leaf from the bottom), young leaf (second leaf from the top), and seeds were collected from three different plants of each type. Values are the mean ± sd (n = 3). Similar data for wild-type plants could not be obtained because these plants did not grow further in the presence of 5 mm ZnCl₂. However, the relative values for zinc in the wild-type plants grown in water were almost negligible: 0.01% in roots; 0.008% in old leaf; 0.005% in young leaf; and 0.005% in seeds. C, Comparison of various growth parameters and seed production of wild-type and glyoxalase transgenic tobacco plants grown in the presence of water and 5 mm ZnCl₂, respectively, for 150 d.