Abstract

The dehydration-responsive element-binding protein (DREB) is a subgroup member of the AP2/ERF family and actively participates in the response of plants to abiotic stress. AlthoughDREBgenes have been studied in a variety of plant species, there are few reports ofDREBgenes in sugarcane (Saccharumspp.). In this study, a novel full-length cDNA sequence of theScDREB2B-1gene was cloned from theSaccharumhybrid ROC22, whose encoding protein contained only one AP2-conserved domain and was clustered into the DREB (A-2) subgroup. The diverse promoter elements in theScDREB2B-1gene and the accumulated transcripts of its homologous gene (SsAP2/ERF-107) inS. spontaneumunder drought stress suggest that theScDREB2B-1gene may play a role in drought response. In addition, reverse transcription quantitative PCR analysis showed that the expression level of theScDREB2B-1gene was upregulated in the root and leaf of ROC22 under polyethylene glycol, sodium chloride and abscisic acid (ABA) treatments. The yeast two-hybrid experiment demonstrated that ScDREB2B-1 had transcriptional self-activation activity. Compared with wild-type plants, the overexpression of theScDREB2B-1gene improved the drought tolerance of the transgenicNicotiana benthamianaby activating the ABA pathway to enhance the expression of the ABA-responsive gene (NbNCED) and ABA content, regulate the intracellular reactive oxygen species (ROS) level (enhance the transcripts of ROS synthase-related geneNbRbohBand the activities of catalase, peroxidase and superoxide dismutase) and increase the relative water content, proline content and expression level of osmotic stress-related genes (NbERDandNbLEA). Collectively, our data indicate thatScDREB2B-1is a stress-inducible and ABA-responsive transcription factor gene that responds to drought stress by regulating ABA signaling, ROS levels and stress-related gene expression. This study