Cloning and characterization of an ABA-independent DREB transcription factor gene, HcDREB2, in Hemarthria compressa

BACKGROUND Hemarthria compressa is a stoloniferous perennial tropical forage grass with a wide geographic distribution; however, environmental stress has a great influence on its growth. The DREB transcription factor family genes contains candidate genes for improving plant stress tolerance. RESULTS From cold-treated H. compressa plants, a putative DREB2 gene (HcDREB2) was cloned using the RACE-PCR method. HcDREB2 was 1296 bp in length and encoded a putative protein 264 amino acid residues long. HcDREB2 shared the highest sequence identity with DREB2 in sorghum. The expression of HcDREB2 was independent of ABA treatment, but inducible by low temperatures as well as drought and high salinity treatments. Yeast one-hybrid assays showed that HcDREB2 directly bound the DRE cis-acting element to transactivate the expression of the downstream reporter genes. CONCLUSIONS HcDREB2, a stress-inducible but ABA-independent transcription factor gene, can transactivate downstream genes by binding to the DRE cis-element. The current results are a foundation for making use of this stress tolerance gene in future H. compressa studies.