Figure 8.

Salt application on detached leaf elicits Ca²⁺ waves along the vascular tissue. (A) Time series of images (time of capture indicated in the right top corner of each image in min:s) showing propagation of Ca²⁺ responses in a detached leaf. First image of the series is a bright-field view of the plant. At time = 1 min, 100 μL of a solution of NaCl (200 mM) was dispensed onto the petiole (white arrow) and light subsequently emitted from leaves was integrated over 7 min (each image shows cumulative light over a 15 s time lapse). Ca²⁺ responses were immediately detected on petioles and propagation of Ca²⁺ responses to the end of leaf was observed. Scale bar = 1 cm. Calibration bar in gray scale is shown in the last image (RLU). Representative result of five independent experiments. (B) Quantification of light signals from ROI for the whole leaf (see C) over 8 min (in RLU per 15 s). At time = 1 min, NaCl was applied onto the petiole (black arrow). The two peaks denoted by * and ** correspond to a Ca²⁺ increase in the basal third and the rest of the leaf respectively. (C) Localization of Ca²⁺ responses is represented by a z-stack of standard deviation of Ca²⁺ signals over the 8 min of measurement. Ca²⁺ signals seem to take place in leaf veins. The basal third of the leaf is indicated by * and the rest of the leaf by **. Line scan of primary vein (red dashed line X–Y) is analyzed in (D). (D) Kymographic representation of Ca²⁺ signals in the primary vein (X–Y from C). Three different velocities of Ca²⁺ signals could be measured and are indicated.