Figure 4.
(A) Colocalization of RFP-TSN1 (red), RFP-TSN2 (red), and RFP-Rbp47b (red) with MT labeled by GFP-β-tubulin (green) in N. benthamiana leaf epidermal cells. Two days after infiltration, the leaves were heat-stressed at 39°C for 40 min. N-terminal GFP and RFP fusion proteins were expressed under the control of the 35S promoter. Arrows denote colocalization. Bars = 5 μm.
(B) Selected time frames showing the movement of SGs (red; denoted by arrows) along MTs (green). Bar = 4 μm.
(C) and (D) Treatment with APM (C) or taxol (D) inhibits the formation of TSN and Rbp47b foci in root tip cells. Five-day-old Arabidopsis Col seedlings expressing ProTSN:GFP-TSN and Pro35S:RFP-Rbp47b were treated with APM (10 μM), taxol (20 μM), or DMSO (at the same concentrations; mock) for 5 h at room temperature. APM- and taxol-treated seedlings were washed and incubated for 2 h in liquid MS medium (wash out). Heat stress was induced for 40 min at 39°C. Seedlings grown under 23°C were used as a control. Graphs show mean numbers ± sd of TSN or Rbp47b foci per 100 μm2 of cytoplasm counted in 5 to 10 plants per treatment in three independent experiments. Means with different letters are significantly different at P < 0.05, Student’s t test. Bars = 2 μm.
(E) Formation of TSN foci is inhibited in the Arabidopsis MT mutants clasp, mor1-1, and fra2. Seedlings were heat-stressed at 39°C for 40 min and then immunostained with anti-TSN (red). Control seedlings were grown at 23°C. DNA staining with 4′,6-diamidino-2-phenylindole is shown in blue. The graph shows mean numbers ± sd of TSN foci per cell counted in 5 to 10 plants in each triplicate experiment. ***P < 0.001 versus the wild type, Dunnett’s test. Bars = 2 μm.