Figure 8.

The siz1-2 and mms21-1 Mutations Do Not Substantially Alter the mRNA and Protein Abundances of SUMO1/SUMO2 Targets Selectively Modified by SIZ1.

(A) Scatterplot comparing the transcript abundance for 112 SIZ1-influenced SUMO1/SUMO2 targets both before and 30 min after a 37°C heat stress (HS). mRNA levels for the 112 targets significantly influenced by SIZ1 (see Figure 4) were determined by RNA-seq of total seedling RNA. The log₂ fold change of siz1-2 versus the wild type was compared without or with HS. The dashed box delineates a twofold change in mRNA abundance. Only three transcripts achieve a >2-fold difference in expression, whereas only nine others had slightly significant changes in expression (±HS) below this 2-fold change.

(B) Total proteome analysis comparing unstressed siz1-2 (right) and mms21 seedlings (left) with wild-type seedlings. Total protein from 8-d-old seedlings was trypsinized and subjected to tandem LC-MS. Protein abundances as determined by MS1 peak areas were plotted for the mutants versus the wild type. Protein groups (including isoforms) detected from the complete Arabidopsis proteome (1758 for siz1-2 versus the wild type and 1752 for mms21 versus the wild type), members of the abundant SUMO1/SUMO2 target list (454 total), and members of the SIZ1-influenced target list (112 total) are indicated by the black, green, and red dots, respectively. Dashed lines represent 2-fold changes up or down in protein abundance. Notable SUMO1/SUMO2 targets in (A) and (B) that are influenced by SIZ1 are indicated (see Figure 6).