Abstract
The ZmCBF3 gene is a member of AP2/ERF transcription factor family, which is a large family of plant-specific transcription factors that share a well-conserved DNA-binding domain. To understand the regulatory mechanism of ZmCBF3 gene expression, we isolated and characterized the ZmCBF3 promoter (PZmCBF3). Three deletion fragments of PZmCBF3 were generated, C1–C3, from the translation start codon at position −1079, −638, and −234, and fused to the GUS reporter gene. Each deletion construct was analyzed by Agrobacterium-mediated stable transformation and expression in Arabidopsis thaliana. GUS expression assays indicated that the PZmCBF3 exhibited root-specific expression activity. A 234-bp fragment upstream of the ZmCBF3 gene conferred a high level of GUS activity in Arabidopsis. Some cis-acting elements involved in the down-regulation of gene expression were detected in the promoter, encompassing positions −1079 to −234. PZmCBF3 was activated by cold stress. The MYCCONSENSUSAT elements (CANNTG) were responsible for the ability of PZmCBF3 to respond to cold stress. The results of the present study suggest that PZmCBF3 might play a role in cold tolerance in maize.
Highlights
Drought, high salinity, and low temperature are common stress conditions that have adverse effects on plant survival, growth, and reproduction
To characterize the promoter of ZmCBF3 (PZmCBF3), the 5′-upstream sequence was cloned from maize (B73) genomic DNA
GUS expression assays indicated that the ZmCBF3 gene exhibited root-specific expression
Summary
High salinity, and low temperature are common stress conditions that have adverse effects on plant survival, growth, and reproduction. To continue growth and reproduction under such conditions of abiotic stresses, plants respond to unfavorable environments by using various developmental, physiological, and biochemical mechanisms. The C-repeat (CRT)/DRE (dehydration-responsive element) motif-binding transcription factors (CBFs) are identified as stress-responsive genes. Low temperatures can induce the expression of CBFs in plants, as well as enhance frost resistance [1,2]. The CBFs can bind to the CRT/DRE element, which is located in the promoter region of cold-regulated genes and upregulates their expression and increases frost/freeze tolerance in plants [3]. The CBF gene family includes CBF1, CBF2, CBF3, and CBF4 These four genes play an important role in plants that improve resistance to cold, drought, and salt. Using the yeast one-hybrid system, AtCBF1, which binds to CRT/DRE, was identified in an Arabidopsis gene library [1]
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