Figure 1.

Absolute amounts and carbon isotope redistribution in photorespiratory intermediates and ethanolamine. Shown are (A) absolute amounts of selected photorespiratory intermediates and ethanolamine (ETA) and (B) redistribution of ¹³C in selected photorespiratory intermediates (serine (flux from glycine), 3HP (flux from serine) and glycerate (flux from 3HP)) and ETA (flux from serine) following [U-¹³C]-glucose labeling in the wild type and the hpr1 mutant. Plants were grown under controlled environmental conditions (390 ppm CO₂, ~120 µmol m⁻² light intensity, 20/18 °C day/night temperature, ~70% relative humidity) for 5 weeks (12/12 h day/night cycle). At this time point, leaf-discs were obtained for absolute metabolite quantification and carbon isotope labeling. Shown are means ± SD of five biological replicates (5 leaf-discs per plant) and asterisks show significant changes compared with the wild type according to Student’s t-test (** p < 0.01).