Figure 4.

In vivo incorporation rates of [¹⁴C]Phe into roots (A) and rosettes (B) of intact wild-type (gray bars) and pig1-1 (white bars) plantlets. Roots of 2-week-old plantlets were incubated in half-strength MS, 0.5% Suc, 1 mm Phe (specific activity 23.1 MBq mmol⁻¹) at a PFD of 60 μmol m⁻² s⁻¹ for 3 and 6 h. For the plotted data, the calculated incorporation rates after 3 and 6 h have been averaged and are given ±sd. The plantlets had been germinated and grown for 14 d on half-strength MS, 0.5% Suc plates with (hatched bars) or without (solid bars) 1 mm unlabeled Phe prior to the experiment. The radiolabel detected in the rosette corresponds to the amount of Phe transported from the root with the xylem stream. No significant differences between pig1-1 and the wild type were detected with a Welsh test. Three replicates consisting of two plantlets each were conducted for each time point. For simplicity reasons, the data for roots are also normalized to the chlorophyll content of the corresponding rosette sample, by which the qualitative result was retained in comparison to normalization to fresh weight (data not shown).