Figure 5.

Respiration parameters in leaf discs from wild-type (WT) and tdt plants. A and B, ¹⁴CO₂ evolution from isolated leaf discs was determined under light conditions. The leaf discs were taken from 5-week-old plants and incubated in 10 mm MES-KOH solution, pH 6.5, 0.3 mm Glc, and 0.1 mm CaSO₄ supplemented with 0.62 kBq mL⁻¹ [1-¹⁴C]Glc (A) or [3,4-¹⁴C]Glc (B) at an irradiance of 100 μmol m⁻² s⁻¹. The ¹⁴CO₂ released was captured (at hourly intervals) in a KOH trap, and the amount of radiolabel released was quantified subsequently by liquid scintillation counting. C, Ratio of carbon dioxide evolution from C3,4 to C1 positions of Glc in leaves of tdt plants. Values are presented as means ± se (n = 3). D, Dark respiration measurements performed on 5-week-old plants. Values presented are means ± se (n = 10) obtained in two independent assays (five plants in each assay). Asterisks indicate values that were determined by Student’s t test to be significantly different (P < 0.05) from the wild type.