Figure 1.
Example [13C]methanol pulse-chase experiment on a detached branch of I. edulis showing real-time [13C]labeling and unlabeling dynamics of C1 and C2 volatile metabolites using proton transfer reaction–mass spectrometry (PTR-MS) (absolute emissions in (a) and relative emissions in (b)). Emissions of [13C]formaldehyde was estimated by subtraction of the interference by the O2+ ion at m/z 32. In addition, 13CO2 isotope flux through the dynamic headspace atmosphere are also shown up to the end of the [13C]methanol labeling period and are based on air sample collections in vials and offline isotope ratio analysis by isotope ratio mass spectrometry (IRMS). Vertical dashed lines indicate a rapid change of solutions delivered to the transpiration stream (i.e., [12C]methanol to [13C]methanol and vice versa).