Figure 4.

Effects of tunicamycin and mannose on Arabidopsis roots. Bright field (a, b, c, and d) and epifluorescence images (e, f, g, and h) of Arabidopsis root tips stained with the callose-specific fluorescent dye sirofluor. Roots were cultured for 5 days on MS media with the following supplements: a and e, none; b and f, 2 μM tunicamycin; c and g, 5 μM tunicamycin; d and h, 0.1% mannose. Asterisks point out swollen epidermal cells. (Bar, 150 μm.) Time curve of longitudinal growth (i) and radial swelling (k) of Arabidopsis roots incubated with 0 μM (black), 1 μM (blue), and 2 μM tunicamycin (red). Vertical bars indicate standard deviations (sample size between 12 and 18). Tunicamycin concentrations of 0.5 μM and lower had no significant effect on longitudinal growth, whereas concentrations of 5 μM and higher completely arrested it. Concentrations of 1 μM and lower, as well as 5 μM and higher, did not cause significant radial swelling. For the sake of clarity these results are not included in the figure.