Isolation and characterization of three DREB-like genes encoding dehydration-responsive element binding proteins in chicory (Cichorium intybus)

Three novel DREB (Dehydration-Responsive Element Binding protein) genes, designated as CiDREB2A, CiDREB5A and CiDREB6A, were individually isolated from chicory (Cichorium intybus L). Based on phylogenetic tree analysis, all three genes possessed a conserved AP2/EREBP domain and were subsequently categorized into the A2, A5, and A6 subgroups within the DREB subfamily, respectively. All of them contained a conserved AP2/EREBP domain and were classified into the A2, A5 and A6 subgroup of the DREB subfamily based on phylogenetic tree analysis, respectively. Quantitative real-time PCR analysis indicated that these genes were all induced by abiotic stresses. A subcellular localization assay revealed that these CiDREBs were localized in the nucleus. In addition, these three CiDREB proteins were also identified to bind the DRE motif of RD19A as shown by yeast one-hybrid experiments. Overexpression of CiDREB2A was found to promote sensitivity to high temperature at the post-germination stages in Arabidopsis while expression of heat shock proteins were decreased in the overexpressing plants compared to that of the control group under high temperature treatment. These results suggest that these CiDREBs may play an important role in regulation of stress-responsive signaling in chicory.