Molecular Identification of Twenty NtDREB Homologs and Overexpression of NtDREB_A2.1 Improved Plant Growth in Response to Cold-Stress and P-nutrition Limitation

Being as a useful model plant for biological study and significant industrial-crop that is sensitive to low temperature, tobacco is frequently adopted to evaluate functions of interested genes from other species by heterologous expression. Dehydration-responsive element binding (DREB) proteins are a type of transcription factors involved in plant responses to abiotic/biotic stimuli. However, genetic information and molecular-physiological roles of tobacco DREBs are little described. Here, we identified 20 NtDREBs containing a typical AP2-domain and phylogenetically classified them into five subgroups (A2-A6). Inspecting promoter sequences of NtDREBs revealed a different enrichment of certain abiotic stress-related cis-elements including 'MeJA- and ABAresponsive and A/T-rich binding' components. Analysis of publicly available RNA-seq data showed that many NtDREBs were transcriptionally regulated by cold-treatment. Furthermore, we assessed physiological roles in tobacco of NtDREB_A2.1, because of its rapid and/or strong expression responsive to low temperature and plant P- and N-nutritional status. Overexpression of NtDREB_A2.1 in tobacco cultivated under 15 degrees C improved the growth with increased plant-height and leaf-area compared to WT. Interestingly, NtDREB_A2.1 overexpression negatively influenced plant growth under conditions of low/high N-supply and 15 degrees C, whereas NtDREB_A2.1transgenic lines could effectively utilize external low- and/or high P for better growth with increased N- and Paccumulation under 15-25 degrees C. Our work added not only new members to the DREB-subfamily but a valuable molecular-target for engineering of crops, aiming at improvement of plant cold-tolerance and utilization of soil phosphorus occurring at low available levels for plants in most soils.