Fig. 11.

Role of cytokinins dominates over environmental stress-related cis-elements in cold-induced RRA up-regulation in Brassica species. (A) Comparison of the number of environmental stress-related cis-elements identified using the PlantCARE databases (Lescot et al., 2002) in the promoter regions of A. thaliana and Brassica RRA genes along with the percentage of RRA genes where these cis-elements were found. (B) Pearson correlation (with 95% confidence interval, shadowed part) between the transcriptional response of cold-responsive A. thaliana and Brassica RRA genes after 4 h of cold treatment and the number of environmental cis-elements present in their promoter regions. (C) Expression of ARR7 and its homologs after incubation of 1-week-old seedlings in medium supplemented with either DMSO or the cytokinin antagonist PI-55 (0.1 µM/1 µM) and exposure for 4 h to either cold or control conditions. The expression data are presented as log2 fold change double normalized by the delta-delta Ct (Pfaffl, 2004) (means ± SE) to the corresponding housekeeping gene (see the Materials and methods) and the control. The different letters indicate variable groups with statistically significant differences (P<0.05, Tukey’s HSD).