Sugarcane Confers Drought Stress Tolerance in Transgenic by Regulating the ABA Signal, ROS Level and Stress-Related Gene Expression

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. Although genes have been studied in a variety of plant species, there are few reports of genes in sugarcane ( spp.). In this study, a novel full-length cDNA sequence of the gene was cloned from the hybrid ROC22, whose encoding protein contained only one AP2-conserved domain and was clustered into the DREB (A-2) subgroup. The diverse promoter elements in the gene and the accumulated transcripts of its homologous gene () in under drought stress suggest that the gene may play a role in drought response. In addition, reverse transcription quantitative PCR analysis showed that the expression level of the gene 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 the gene improved the drought tolerance of the transgenic by activating the ABA pathway to enhance the expression of the ABA-responsive gene () and ABA content, regulate the intracellular reactive oxygen species (ROS) level (enhance the transcripts of ROS synthase-related gene and the activities of catalase, peroxidase and superoxide dismutase) and increase the relative water content, proline content and expression level of osmotic stress-related genes ( and ). Collectively, our data indicate that is 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 contributes to a better understanding of the biological function of , which could serve as a foundation for future resistance breeding in sugarcane.