Isolation and characterization of a cold-induced DREB gene from Aloe vera L.

A new cold-induced dehydration-responsive element-binding (DREB) gene encoding an AP2/ethylene response element binding protein transcription factor was isolated from Aloe vera L. by rapid amplification of complementary DNA ends (RACE). The deduced protein contained a putative acidic activation domain and an AP2 DNA binding domain of 64 amino acids. The expression analysis showed that the transcripts accumulated rapidly under cold stress and peaked at 12 h, then decreased to the original level. Yeast one-hybrid analysis indicated that Aloe DREB I can bind to DRE cis-elements and activate the expressions of reporter genes, but the binding and activation abilities were weak. Aloe DREB1 localized in nucleus, although it lacks typical nuclear localization signal. These results implied that Aloe DREB1 might function as a transcription activator involved in the regulation of cold-responsive genes via signal transduction pathway dependent or independent of the DREB transcription factor.