Fig. 5: SYP121-associated TGN/EE are recruited to the plus end of microtubules and delivered to the cell surface by microtubule growth.

a Left: A representative time series of partial region in a guard cell (the image of intact cells was shown in Supplementary Fig. 9c) expressing AtEB1b-GFP and mCherry-SYP121. Spinning disc confocal microscopy was used and the focal plane was the interior of the cell. A SYP121-associated TGN/EE (magenta) moved away from the cell periphery (marked by a white dashed line). At 20 s, an AtEB1b-GFP dot (green) suddenly appeared and a co-localisation between AtEB1b-GFP and the mCherry-SYP121-associated TGN/EE was detected (white arrowheads). The SYP121-associated TGN/EE then changed its direction and moved toward the cell periphery. Better visualisation required increasing contrast (post-acquisition). White arrows indicate the moving direction of a mCherry-SYP121-associated TGN/EE. Bar = 2 µm. Right: The graphic depicts the moving tracks of AtEB1b-GFP particle and mCherry-SYP121-associated TGN/EE shown in the left panel. The whole tracking path with AtEB1b in green and SYP121 tracks in white (when co-localised with AtEB1b) or magenta (when no co-localisation was observed). b Left: Variable-angle epifluorescence microscopy was used to observe the co-localisation of mCherry-SYP121 with AtEB1b-GFP and their approach to the cell surface. A representative time series was shown. A mCherry-SYP121-associated TGN/EE (white arrowheads) appears and is stabilised at the cell surface at 0 s, and remained stationary for several seconds before its fluorescence faded at 8 s. Bar = 1.5 µm. *indicated the AtEB1b-GFP dots being tracked. Right: Kymograph of the region indicated in the left panel (white dash arrow), showing the stationary phase of mCherry-SYP121-associated TGN/EE co-localised with AtEB1b-GFP. The green and magenta arrows represent the AtEB1b and SYP121 trajectory, respectively.