Dehydration-responsive element-binding transcription factor, GuDREB35, positively regulates drought tolerance in licorice (Glycyrrhiza uralensis)

Dehydration-responsive element-binding (DREB) transcription factors associated with abiotic stress responses. However, an understanding of the DREB gene family and its functions in drought tolerance in licorice (Glycyrrhiza uralensis) is limited. In this study, 79 GuDREB genes were identified across the licorice genome and divided into six major groups. In addition, we provided information on the phylogenetic relationships, gene structures, conserved motifs, collinear relationships and cis-regulatory elements of GuDREBs. Bioinformatical and gene expression pattern analysis showed that the expression of the GuDREB35 of the A5 group was considerably induced by drought stress. Overexpression of GuDREB35 significantly enhanced drought tolerance and promoted flavonoid accumulation in licorice. Conversely, GuDREB35-RNAi plants exhibit significantly reduced drought resistance and a significant decrease in flavonoid levels. Transcriptomic analysis revealed that the overexpression of GuDREB35 up-regulated the expression of genes involved in antioxidant defense and flavonoid biosynthesis. Protein-DNA interaction studies further confirmed that GuDREB35 directly bound to the promoters of GuBGLU12 and GuOMT1, which are two enzymes in the flavonoid synthesis pathway. Our research demonstrates that GuDREB35 enhances drought stress tolerance by activating antioxidant defense and flavonoid biosynthesis pathways, providing a theoretical foundation for understanding the molecular mechanisms of drought tolerance and developing drought-resistant licorice varieties.