Fig. 4: HPTS allocation patterns highlight the differential sink strength of organs.

A Drawing showing the experimental setup. Shoot apices were treated by dipping stems in liquid ACM media with (top) or without HPTS (bottom). B HPTS (green) pattern after different incubation times in dissected meristems. Images are representative from n = 5, repeated twice. C Meristem obtained from the experiment shown in (B) showing a maximum intensity projection of HPTS pattern after 6 h of incubation. Organ stages P5, P6, and P7 are indicated. D Orthogonal sections illustrate the sampled layers (dashed white line in L1 and L2) of P5 and P7, after 6 h of dye incubation. For reference, meristem domains are indicated: top yellow line (CZ and PZ), red line (BZ), and green line (organ), see methods for sampling details. HPTS signal intensity profile plot showing the average (green line) and 95% confidence interval (light green) for L1L2 extracted from orthogonal sections (n = 5). E Orthogonal sections showing HPTS and plasma membrane (pUBQ10::LTi6B-TdTomato) signal intensities for P7 organs after 6 h of incubation. The white dotted lines define the limits of the stack of slices that were projected to obtain panel (F). Images are representative from n = 5, repeated twice. F Maximal projection of a 5 μm-thick transversal section in P7 organs showing HPTS and plasma membrane signal. G Maximum intensity projection of HPTS pattern of aba2-1 after 6 h of incubation. Images are representative from n = 5, repeated twice. H Single meristem slice of aba2-1 showing the HPTS, PI, and merged signals. I Close-up of CZ cells showing HPTS localization in Col-0 and aba2-1 after 6 h of incubation. Images are representative of n = 5. J Orthogonal section of aba2-1 after 6 h of incubation obtained as done in D for HPTS signal analysis. The white arrow indicates the boundary exclusion zone. K HPTS signal intensity profile plot showing the average (green line) and 95% confidence interval (light green) for L1L2 (n = 7). Data was obtained after 6 h of incubation. Heatmaps indicate the HPTS signal intensity. Scale bars = 50 μm. All experiments were independently reproduced at least once.