Figure 7.

Relative tolerance of transgenic tobacco plants overexpressing glyoxalase I (GI), glyoxalase II (GII), or both glyoxalase I and glyoxalase II in double transgenics (GI + II), toward toxic levels of zinc, cadmium, and lead. Representative images showing phenotypic differences (A) and chlorophyll content (B; μg g⁻¹ fresh weight) from heavy metal-treated leaf discs of wild-type and various transgenic plants (GI, GII, and GI + II) after incubation in 20 mm solution of ZnCl₂, CdCl₂, or PbNO₃ for 5 d are shown. Discs floated in water served as the experimental control. The sd in each case is represented by the vertical bar in each graph (n = 3). Note the difference in retention of chlorophyll in wild-type and transgenic plants in response to various heavy metals.