Functional Characterization Of A Maize Transcription Factor-ZmbZIP16

Basic leucine zipper is one of the largest transcription factor gene families in eukayotic organism. It plays an important role in plant development and abiotic stress response. Compared to the studies of bZIPs in Arabidopsis, fewer bZIPs in maize has been characterised. We have cloned maize bZIP16 and investigated its function in abiotic stress tolerance by overexpresing it in Arabidopsis. The reuslts of this thesis are listed as follows:Using qRT-PCR, the transcriptional level of ZmbZIP16 was elevated after 2hr dehydration treatment. By fusing ZmbZIP16 with GFP, this protein was localised in the nucleus. By incubating ZmbZIP16 protein with different forms of G-box element and performing EMSA, ZmbZIP16 was confirmed to bind to G-box specifically.Dual luciferase vector was constructed using the promoter of ZmGols2 to control the expression of Rluc. By co-transformation of the Dual luciferase vector(effector) and the ZmbZIP16/GFP overexpression vector(donor), we found ZmbZIP16 down-regulated ZmGols2, however, the truncated ZmGols2 promoter contain the G-box element was not regulated compared with the control. Consequently, ZmbZIP16 may regulate ZmGols2 indirectly.In vitro dephosphorylation assay indicated that ZmbZIP16 could be phosphorylated under nomal and ABA treatment, and the ABA treated sample showed more highly phosphorylated state. Furthermore, using SFLC system, 3 MAPK candidates were identified to interact with ZmbZIP16.By overexpressing ZmbZIP16 in Arabidopsis thaliana, transgene lines with high expression level showed drought resistance after three-week drought stress treatment, and the relative leakage of transgene lines were lower that WT and GFP control.