Fig. 3

Labeling patterns generated by feeding of dyes through the petiole or the hypocotyl of A. thaliana rosettes. Plants were grown on soil under 8 h short day conditions to developmental stage 1.10–1.15. a Petiole feeding using a transition leaf between young rosette leaves with sink characteristics and mature source leaves [36]. b Hypocotyl feeding using a plant grown under identical conditions. Representative photographs were taken 1 h after start of feeding with a 20 mg mL⁻¹ solution of Erioglaucine disodium salt, i.e. Brilliant Blue FCF, in tap water. Arrows indicate the position of the vial that contained the feeding solution. c Scheme of the dye-labeling pattern resulting from the petiole feeding assay (PFA). d Scheme of the dye-labeling pattern resulting from the hypocotyl-feeding assay (HFA). e PFA feeding using 6-Carboxyfluorescein diacetate (CFDA). A section of labeled and non-labeled leaves at different stages is shown. The excitation and emission filters were set to λ = 470 ± 40 nm and λ = 525 ± 50 nm, respectively. The arrow indicates the position of the vial that contained the feeding solution. f A longitudinal optical section obtained by confocal laser scanning through a xylem vessel (Xyl) and adjacent CFDA-labeled phloem and phloem companion cells of a petiole (Phl). The excitation and emission filters were set to λ = 488 nm and λ = 560 nm, respectively