Fig. 1

Effect of abiotic stresses on expression and steady-state level of proteasome subunits. A Microarray data of Arabidopsis seedlings exposed to cold (4 °C), osmotic (300 mM mannitol), salt (150 mM NaCl), drought (air stream), genotoxic (1.5 μg/ml bleomycin), oxidative (10 μM methyl viologen), UV-B, wounding, and heat shock (38 °C) stresses from Kilian et al. [37] were obtained via the BAR Expression Browser (http://bar.utoronto.ca/) and organized into a heat map using Morpheus (broadinstitute.org). Heat map displays log₂-transformed expression-fold changes with min/max cut-off values of − 2/+ 2. Note that for heat stress, the 4.0- to 24.0-h time points represent variable 25 °C recovery times (Rcvry) following an initial 3.0-h heat shock (HS) at 38 °C. B Eight-day-old PAG1-FLAG seedlings were exposed to 10 μM methyl viologen (MV), 300 mM mannitol (Mtl), and 150 mM NaCl for 12 and 24 h. Anti-FLAG, anti-PBA1, and anti-RPN1 immunoblots of PAG1-FLAG total lysates were resolved on 12% SDS-PAGE, highlighting representative subunits of the CP α-ring, β-ring, and RP lid, respectively. Loading was normalized based on fresh weight and a Ponceau S stain is included as a loading control. It should be noted that the overall protein profiles as revealed by Ponceau S staining in B for either 12- or 24-h treatments are comparable suggesting viable seedlings. Three biological replicates were performed, and quantification of protein levels is shown in (C), and no significant change was observed