2.10. Carbohydrate translocation
Determination of carbohydrate translocation was based on the method of Gilbert et al. (1997). Flower stems with leaves were cut from the plants. To remove the upper parts with flowers and flower buds, the stems were re-cut to 20 cm and the cut ends of the stems were put into distilled water. The stems were held at 25 C under 250mmol m2 s1 cool-white fluorescence lamps for about 1 h, and then individual leaves were cut from the stems and the cut ends were put into distilled water and placed in a 27-L acrylic chamber. Then, 14C-sodium bicarbonate (NaH14CO3) (9.25 MBq, 74 MBq mmol1) was dissolved in water and lactic acid was added to the solution to evolve 14CO2. Leaves were allowed to photosynthesize for 30 min, after which the cut ends were placed in 20 mM EDTA solution and held at 20 C in darkness for 3 h. The resulting solutions were evaporated to dryness in vacuo below 50 C. The residue was dissolved in distilled water and separated with HPLC equipped with the radio-analyzer as described above.