Figure 2

Testing of the single leaf labelling cuvette. Pictures (A, C, E) and autoradiograms (B, D, F) of Col-0 rosettes labelled with ¹⁴CO₂. (A and B) Leaf 8 was introduced to the cuvette when still attached to the rosette. Just before labelling for 10 min with ¹⁴CO₂, the petiole of leaf 8 was cut to prevent phloem export. (C and D) A rosette was placed for 60 min next to the leaf cuvette, which was being used to label other plants during a series of 5 pulse and chase experiments. (E and F) The ¹⁴C distribution pattern observed when the leaf cuvette is deliberately opened slightly during labelling in order to cause a leak. Leaf 8 was labelled for 5 min followed by a chase period of 1 h. The leaves are numbered according to the sequence of emergence where 1 is the first emerging true leaf after the cotyledons. Here, leaves 3 and upwards are indicated. Dried plant material was exposed to the film for 7 days.