Relative Quantification of Phloem Loading with 13CO2 in Grass Leaves.

A central challenge in plant physiology research is tracking the movement of photoassimilates, especially following their allocation via the phloem. To obtain better insight into movement of photoassimilates, we present a stable isotope-based approach to measure photoassimilate export from leaves. In this simple procedure, 13CO2 pulse label is supplied to whole leaves or defined sections of the leaves, sugars are extracted at two timepoints and the reduction of 13C -signal quantified. The method uses the stable 13C isotope of carbon, is safe to use, and has been successfully applied in both monocot and dicot species.