Figure 6.

Impact of bzip60-2 on the Expression of Various Genes at Different MDTs.

(A) Box plots showing the relative expression of various genes downregulated in bzip60-2 compared with W22 at different MDTs and at developmental stage V4 (20 DAG). See legend in Figure 2F for an explanation of box-plot features.

(B) Coexpression in maize mesophyll protoplasts of 35S:bZIP60s and various promoters linked to luciferase. Promoter activity is expressed as the relative activity of firefly luciferase versus Renilla luciferase. Values in red indicate the fold increase in expression plus or minus bZIP60s. Numbers in parentheses indicate the number of UPRE- or ERSE-like sequences in the promoters, which average ∼1.0 to 1.5 kb in size. Serpin-Z1 (Zm00001d013737) without obvious UPRE or ERSE elements in its promoter served as a negative control.

(C) Activity of the HSFTF13 promoter and various promoter mutants in maize mesophyll protoplasts. Here, 1.5 kb of the HSFTF13 promoter was linked to firefly luciferase, and UPR promoter elements in the distal region (M1) containing two UPRE-III elements and a UPRE-I element were mutated as described in “Methods.” The proximal region (M2) containing a UPRE-III element and bZIP17/28 binding site were also mutated. The constructs were cotransfected with 35S:bZIP60s in maize protoplasts as above and assessed for luciferase activities. Promoter activity is expressed as the relative activity of firefly luciferase versus Renilla luciferase. VC, empty vector control used for bZIP60s overexpression. Values are the means of four replicates ± sd. Different letters indicate significant differences between comparisons (P < 0.05, one-way ANOVA).