Fig. 1.

flg22 transport in plants requires FLS2 receptor. flg22 is detected in vascular regions. (A) FAM–flg22 (Ff22) was detected on the adaxial side of a detached Col leaf 1 h after drop application of 10 μM peptide to the abaxial side. Migration of FAM–scrambled peptide (Fscr) in Col and FAM–flg22 in fls2 and bak1 was significantly lower. FAM fluorescence was quantified in epifluorescence microscopy images of adaxial (distal) leaf side; data combined from three experiments are shown as percentage of FAM–flg22 signal in Col. Background fluorescence (mock treatment without peptides) is shown by a dashed line. Letters indicate significant difference (P<0.01, ANOVA/Tukey’s test, n≥5). (B, C) FAM–flg22 transport to distal leaves is less efficient in the fls2 mutant. FAM–flg22 or FAM–Y-flg22 (5–10 μM) was infiltrated into one leaf of soil-grown plants, and fluorescence was quantified after 16 h in epifluorescence microscopy images of distal orthostichous leaves (such as in C); data combined from three experiments are shown as percentage of signal in Col. *P<0.02 (t-test, n=12). Background fluorescence is shown by dashed line. (D) Two hours after infiltration of 10 μM FAM–flg22 or FAM–Y-flg22 into a part of Col leaf, FAM fluorescence was detected inside vascular cells outside the infiltrated area. FAM–flg22 in fls2 and FAM–scrambled peptide in Col were rarely detectable outside infiltration area and only between the cells. A composite of confocal microscopy image with differential interference contrast (DIC), green FAM fluorescence and red chloroplast (chl) autofluorescence is shown. Bar: 20 μm. (E) TAMRA–flg22 is detected predominantly in vascular region of Col. Five micomolar TAMRA–flg22 was applied on a filter paper disc placed on the adaxial side of a leaf of in vitro-grown Arabidopsis plants and confocal images of treated tissue (adaxial side underneath filter paper) were obtained 1 d later, after washing the leaf with water. The distinct vein pattern in Col was observed in 4 out of 7 experiments. Bar: 50 μm.