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. 2017 Sep 25;29(10):2433–2449. doi: 10.1105/tpc.17.00309

Figure 6.

Figure 6.

Secondary Wall Patterning Can Be Maintained also in the Absence of MTs.

(A) Representative images of mCherry-TUA5-labeled MT arrays at 0, 8, 16, and 24 h after VND7 induction. Bar = 5 μm.

(B) Representative images of cellulose-stained secondary walls of VND7-induced seedlings 48 h after induction. We applied DMSO or 20 μM oryzalin 8, 16, and 24 h after induction until the final imaging at 48 h after induction to the seedlings. As comparison, a representative image of the secondary wall 24 h after induction is shown on the right. Bar = 5 μm.

(C) Single and time-averaged images of dual-labeled YFP-CesA7 (cyan) and mCherry-TUA5 (magenta) after being treated with DMSO (left panel) or 20 μM oryzalin (right panel) for 4 h. Arrowheads indicate YFP-CesA7 trajectories still localized to distinct bands despite complete depolymerization of the cortical MT array. Bar = 5 μm.

(D) Intensity cross section along dotted line in (C). YFP-CesA7 fluorescence accumulates at distinct bands (indicated by dashed lines) where mCherry-TUA5 fluorescence is absent.

(E) Single images of YFP-CesA7 and mCherry-Tubulin before, during, and after photobleaching a rectangular region (dotted box) in absence (left) and presence (right) of oryzalin (40 µM for 2 h). Bar = 5 µm.

(F) Trans-illumination image in absence (left) and presence (right) of oryzalin showing overlap of secondary wall thickenings and YFP-CesA7 bands (arrowheads).

(G) Fluorescence recovery of secondary wall bands after photobleaching of YFP-CesA7. Bright objects (Golgi, purple circles) were tracked and found accumulating at and moving quickly between the previously bleached bands (see colored tracks coding for the vertical position of the Golgi). Bar = 5 µm.

(H) Kymographs along the dotted lines in (E) show the insertion of individual CesAs to the secondary cell wall band (left) also in absence of MTs (right). Bar = 5 µm.

(I) Velocity of CesA7 inserted into bands in the presence or absence of MTs. Statistical significance was tested by Welch’s unpaired t test: *P < 0.05, **P < 0.005, and ***P < 0.0005.