Cloning and functional identification of stress-resistant BeDREB genes from Bermuda grass

Abstract

Dehydration-responsive element-binding (DREB) proteins, specifically binding to the dehydration-responsive element (DRE), have been identified as a group of important transcription activators of plants which regulate the expression of genes in response to drought, high-salt and low-temperature stresses. Two DREB-like genes from Bermuda grass that are induced by low-temperature or high-salt stresses were cloned using RT-PCR and RACE methods, and were named BeDREB1 and BeDREB2, respectively (GenBank accession No: AY462117 and AY462118). They contained an ORF of 753 bp encoding 251 amino acids, showing the typical characteristics of the DREB gene family. Interestingly, these two genes isolated from Bermuda grass induced either by low-temperature stress or high-salt stress shared 97.8% homology. Furthermore, it was demonstrated that both BeDREB1 and BeDREB2 could bind to the wild-type DRE element to activate the transcription of the reporter gene HIS3, driven by a promoter carrying DRE cis-element in yeast strain 4721, in the presence of 3-AT. RT-PCR showed that BeDREB1 and BeDREB2 genes could be greatly induced by low-temperature and high-salt stresses, respectively. Their expressions were changed following the inducible time. In conclusion, all results indicate that BeDREB1 and BeDREB2 genes isolated from treated Bermuda grass are new members of the DREB transcription activator family, which may play very important roles in signal transduction related to stresses.