Figure 1.
Effects of different inhibitors on primary root elongation.
a–d. Cold-pretreated seeds were cultured in 1/2 MS with 1% Suc for 24 h, and then uniform seedlings of similar size and primary root length were transferred to the same fresh medium containing 0 (a), 20 µM MG132 (b), 40 µM MG132 (c) or 80 µM MG132 (d), respectively, for additional 48 h. Bars = 1000 µm. e–h. Cold-pretreated seeds were cultured in 1/2 MS with 1% Suc for 24 h, and then uniform seedlings of similar size and primary root length were transferred to the same fresh medium containing various concentrations of MG 132 (e), MG115 (f), E-64 (g) and DMSO (h), for additional 48 days. The values are the means ± SD of about 15 seedlings of each treatment. The experiment was repeated thrice with consistent results.
Figure 2.
Effects of MG132 on root-meristem size.
Roots treated with 0 (a), 20 µM MG132 (b), 40 µM MG132 (c) or 80 µM MG132 (d) were stained with FM 4–64, and longitudinal views were obtained using a Zeiss confocal. The results show reduced root-meristem size (indicated by arrows) and accelerated cell differentiation (indicated by stars) in response to MG132 treatment. Bars = 20 µm.
Figure 3.
Arabidopsis carrying GFP-fusion cyclin B were treated with 0 (a), 20 µM (b), 40 µM (c), or 80 µM (d) MG132, respectively. Longitudinal views of the GFP (left) and FM 4–64 (middle) fluorescent emissions were collected separately and then merged (right), using a Zeiss confocal. Figures show accumulation of cyclin B in root-meristemic zone in response to MG132 treatment. Bar = 20 µm.
Figure 4.
MG132 alters cell length in the maturation zone.
Roots treated with 0 (a), 20 µM MG132 (b), 40 µM MG132 (c) or 80 µM MG132 (d) were stained with FM 4–64, and longitudinal views were obtained using a Zeiss confocal. The results show that MG132 alters cell length in the maturation zone (indicated by arrows). Bars = 20 µm.
Figure 5.
Immunofluorescence labeling of ubiquitinated proteins in root cells.
Semi-thin sections of roots treated with 0 (a), 20 µM MG132 (b), 40 µM MG132 (c) or 80 µM MG132 (d) were incubated with anti-ubiquitin antibody and FITC-IgG, and examined with a Zeiss confocal. Arrows show the MG132-induced accumulation of ubiquitinated proteins in vacuoles. Bar = 20 µm.
Figure 6.
LysoTracker staining in root cells.
Seedlings treated with 0 (a), 20 µM (b), 40 µM (c), or 80 µM (d) MG132 were stained with LysoTracker (Green) and FM 4–64 (Red), and examined with a Zeiss confocal. The data show the accumulation of LysoTracker in root cells in response to MG132 treatment. Bar = 50 µm.
Figure 7.
Seedlings treated with 0 (a), 20 µM (b), 40 µM (c), or 80 µM (d) MG132 were stained with MDC (Blue) and FM 4–64 (Red) and examined with a Zeiss confocal. The data show the accumulation of MDC in root cells in response to MG132 treatment. Bar = 20 µm.