Os06g0211200

OsAREB1,an ABRE-binding protein responding to ABA and glucosemay, may function as a positive regulator in drought/heat stresses response,
but a negative regulator in flowering time in Arabidopsis.

Annotated Information

Function

• OsbZIP46 is one member of the third subfamily of bZIP transcription factors in rice (Oryza sativa)
• OsbZIP46 is a positive regulator of ABA signaling and drought stress tolerance of rice depending on its activation.
• The stress-related genes activated by OsbZIP46CA1 are largely different from those activated by the other rice ABF/AREB homologs (such as OsbZIP23), further implying the value of OsbZIP46CA1 in genetic engineering of drought tolerance.

Phenotypic analysis

• Overexpression of the native OsbZIP46 gene increased ABA sensitivity but had no positive effect on drought resistance.
• The activation domain of OsbZIP46 was defined by a series of deletions, and a region (domain D) was identified as having a negative effect on the activation. We produced a constitutive active form of OsbZIP46 (OsbZIP46CA1) with a deletion of domain D. Overexpression of OsbZIP46CA1 in rice significantly increased tolerance to drought and osmotic stresses.
• Gene chip analysis of the two overexpressors (native OsbZIP46 and the constitutive active form OsbZIP46CA1) revealed that a large number of stress-related genes, many of them predicted to be downstream genes of ABF/ AREBs, were activated in the OsbZIP46CA1 overexpressor but not (even down-regulated) in the OsbZIP46 overexpressor.
• OsbZIP46 can interact with homologs of SnRK2 protein kinases that phosphorylate ABFs in Arabidopsis.

Expression

• Expression of OsbZIP46 was strongly induced by drought, heat, hydrogen peroxide, and abscisic acid (ABA) treatment; however, it was not induced by salt and cold stresses.

Evolution

• OsbZIP46 has high sequence similarity to ABA-responsive element binding factor (ABF/AREB) transcription factors ABI5 and OsbZIP23, two transcriptional activators positively regulating stress tolerance in Arabidopsis (Arabidopsis thaliana) and rice, respectively.

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Labs working on this gene

• National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan 430070, China