Constitutive Activation of Transcription Factor OsbZIP46 Improves Drought Tolerance in Rice      

Abstract

OsbZIP46 is one member of the third subfamily of bZIP transcription factors in rice (Oryza sativa). It 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. 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. 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. These results suggest that 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.

The OsMYB30 Transcription Factor Suppresses Cold Tolerance by Interacting with a JAZ Protein and Suppressing β-Amylase Expression

“…For the interaction of OsMYB30 and OsJAZ9 in vivo, we performed a BiFC assay in the rice protoplast system with the pVYNE vector according to a previous study (Waadt et al, 2008;Tang et al, 2012). A co-IP assay was performed using a transient assay based on the rice protoplast system with the isolation and transformation procedures as described previously Zong et al, 2016).…”

A STRESS-RESPONSIVE NAC1-Regulated Protein Phosphatase Gene RiceProtein Phosphatase18Modulates Drought and Oxidative Stress Tolerance through Abscisic Acid-Independent Reactive Oxygen Species Scavenging in Rice

“…The coding region of OsPP18 was amplified and cloned into pDEST32 using Gateway technology (Invitrogen) to generate a bait vector with OsPP18 fused to the GAL4 DNA binding domain. The plasmids that contained SAPKs fused to the GAL4 activation domain (Tang et al, 2012) were cotransformed with the bait plasmid into the yeast strain Mav203 according to the method described previously (Gietz et al, 1997). The protein-protein interaction was determined by colony-lift filter assays (b-gal assay) and the growth of transformants on synthetic complete selection medium containing 20 mM 3-amino-1,2,4-triazole and lacking Leu, Trp, and His.…”

A Drought-Inducible Transcription Factor Delays Reproductive Timing in Rice

“…The DNA binding region preferentially interacts with ABA-responsive elements (ABREs), which are predominantly located in the promoter regions of ABAinducible genes (Jakoby et al, 2002;Nijhawan et al, 2008). A great deal of genetic evidence shows that these ABRE-associated bZIP TFs are involved in drought tolerance response (Kang et al, 2002;Oh et al, 2005;Xiang et al, 2008;Lu et al, 2009;Hossain et al, 2010aHossain et al, , 2010bTang et al, 2012). Until now, none had been shown to regulate rice floral transition in response to drought stress.…”