BnDREB1 confers cadmium tolerance in ramie

Cadmium (Cd) is a toxic heavy metal whose contamination in soil threatens food safety, agricultural production, and human health. To date, phytoremediation is a low-cost and environmentally friendly method for eliminating Cd contamination. In this study, we report a gene from ramie (Boehmeria nivea) that encodes a dehydration responsive element binding (DREB) factor associated with plant tolerance to Cd, namely BnDREB1. The open reading frame of BnDREB1 comprises 873 bp encoding 290 amino acids and includes a characteristic AP2 domain. Its cloned promoter sequence contains various hormone and stress responsive elements. Quantitative RT-PCR analysis showed that BnDREB1 is expressed in different organs of ramie. Treatments with polyethylene glycol (PEG), abscisic acid (ABA), and Cd upregulated the expression of BnDREB1. Confocal microscopic analysis revealed that BnDREB1 is mainly localized in the nucleus. Overexpression of BnDREB1 in Arabidopsis thaliana increased the tolerance of transgenic plants to Cd, thereby protecting plant growth from its toxicity. Biochemical analysis revealed that overexpression of BnDREB1 reduced the levels of Cd induced malonaldehyde and hydrogen peroxide, inhibited the reduction of Cd caused soluble protein contents, increased the Cd accumulation, and enhanced Cd translocation in transgenic plants. Taken together, these findings suggest that BnDREB1 is an appropriate candidate gene for phytoremediation of Cd-contaminated soil .