Limits...
The bZIP protein from Tamarix hispida, ThbZIP1, is ACGT elements binding factor that enhances abiotic stress signaling in transgenic Arabidopsis.

Ji X, Liu G, Liu Y, Zheng L, Nie X, Wang Y - BMC Plant Biol. (2013)

Bottom Line: Two MYCs were found to bind to E-box, in the promoter of ThbZIP1 to activate its expression.Compared with wild-type (Col-0) Arabidopsis, transgenic plants expressing ThbZIP1 had an increased tolerance to drought and salt, but had an increased sensitivity to ABA during seed germination and root growth; meanwhile, ROS level, cell death and water loss rate in transgenic plants were significantly reduced.Based on these data, we suggest that ThbZIP1 confers abiotic stress tolerance through activating stress tolerance genes to modulate ROS scavenging ability and other physiological changes involved in stress tolerance, and plays an important role in the ABA-mediated stress response of T. hispida.

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Laboratory of Tree Genetics and Breeding (Northeast Forestry University), 26 Hexing Road, 150040 Harbin, China. ychngwang@yahoo.com.

ABSTRACT

Background: Tamarix spp. are woody halophyte, which are very tolerant to abiotic stresses such as salinity and drought, but little is known about their specific stress response systems. Basic leucine zipper proteins (bZIPs) play important roles in the ability of plants to withstand adverse environmental conditions. However, their exact roles in abiotic stress tolerance are still not fully known. In the current study, we functionally characterized a bZIP gene (ThbZIP1) from Tamarix hispida in response to abiotic stresses.

Results: We addressed the regulatory network of ThbZIP1 in three levels, i.e. its upstream regulators, the cis-acting elements recognized by ThbZIP1, and its downstream target genes. Two MYCs were found to bind to E-box, in the promoter of ThbZIP1 to activate its expression. Expression of ThbZIP1 is induced by ABA, salt, drought, methyl viologen and cold. ThbZIP1 can specifically bind to ACGT elements, with the highest binding affinity to the C-box, followed by the G-box and lastly the A-box. Compared with wild-type (Col-0) Arabidopsis, transgenic plants expressing ThbZIP1 had an increased tolerance to drought and salt, but had an increased sensitivity to ABA during seed germination and root growth; meanwhile, ROS level, cell death and water loss rate in transgenic plants were significantly reduced. Microarray analyses showed that many ROS scavenging genes were up-regulated by ThbZIP1 under salt stress conditions.

Conclusions: Based on these data, we suggest that ThbZIP1 confers abiotic stress tolerance through activating stress tolerance genes to modulate ROS scavenging ability and other physiological changes involved in stress tolerance, and plays an important role in the ABA-mediated stress response of T. hispida.

Show MeSH

Related in: MedlinePlus

Analyses of the bindings of ThbZIP1 to C-, G- and A-box. A: (a-d): Analysis of the bindings of ThbZIP1 to C-, G-, A-box and their mutated sequences by yeast one-hybrid analysis. The yeast cells were grown on different intensities of selective dropout medias: SD/- Trp-Leu/-His (TDO) + 3-AT (3-AT concentrations, a: 30 mM, b: 40 mM, c: 50 mM, d: 60 mM). B: A diagram of the reporter and effector vectors. C: The coexpression of reporter and effector vector in tobacco leaves. pCAM-C, -G -A, -CM2: three tandem of C-, G-, A-box, or their mutant CM2 was respectively fused to a minimal promoter (-46 to +1) to drive GUS. pROKII-ThbZIP1: the ORF of ThbZIP1 was under the control of CaMV 35S promoter. D: GUS activity assay of the coexpression of reporter and effector plasmid. CaMV35S: The transformation of pCAMBIA1301 alone (positive control). The transformation of the reporter plasmids alone were used as negative controls. All assays were repeated three times and error bars indicate SE.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3852707&req=5

Figure 3: Analyses of the bindings of ThbZIP1 to C-, G- and A-box. A: (a-d): Analysis of the bindings of ThbZIP1 to C-, G-, A-box and their mutated sequences by yeast one-hybrid analysis. The yeast cells were grown on different intensities of selective dropout medias: SD/- Trp-Leu/-His (TDO) + 3-AT (3-AT concentrations, a: 30 mM, b: 40 mM, c: 50 mM, d: 60 mM). B: A diagram of the reporter and effector vectors. C: The coexpression of reporter and effector vector in tobacco leaves. pCAM-C, -G -A, -CM2: three tandem of C-, G-, A-box, or their mutant CM2 was respectively fused to a minimal promoter (-46 to +1) to drive GUS. pROKII-ThbZIP1: the ORF of ThbZIP1 was under the control of CaMV 35S promoter. D: GUS activity assay of the coexpression of reporter and effector plasmid. CaMV35S: The transformation of pCAMBIA1301 alone (positive control). The transformation of the reporter plasmids alone were used as negative controls. All assays were repeated three times and error bars indicate SE.

Mentions: The ThbZIP1 can bind to C-, G- and A-box sequences, but binds more strongly to C-box, followed by G-box and lastly A-box motifs (Figure 3A). Among the four mutants of ACGT elements, ThbZIP1 fails to bind to the CM2 mutant, but is able to bind to the CM1, CM3 and CM4 to some extent. Furthermore, ThbZIP1 is able to bind to CM3 more strongly than CM1 and CM4 (Figure 3A). To confirm these interactions, the effector construct (pROKII–ThbZIP1) and reporter plasmids (pCAM-C-box, -G-box or -A-box) were coexpressed in the tobacco leaves. Consistent with the yeast one-hybrid analyses, GUS staining and activity measurements both showed that ThbZIP1 can bind more strongly to C-box sequences, followed by G-box and A-box (Figure 3C, D).


The bZIP protein from Tamarix hispida, ThbZIP1, is ACGT elements binding factor that enhances abiotic stress signaling in transgenic Arabidopsis.

Ji X, Liu G, Liu Y, Zheng L, Nie X, Wang Y - BMC Plant Biol. (2013)

Analyses of the bindings of ThbZIP1 to C-, G- and A-box. A: (a-d): Analysis of the bindings of ThbZIP1 to C-, G-, A-box and their mutated sequences by yeast one-hybrid analysis. The yeast cells were grown on different intensities of selective dropout medias: SD/- Trp-Leu/-His (TDO) + 3-AT (3-AT concentrations, a: 30 mM, b: 40 mM, c: 50 mM, d: 60 mM). B: A diagram of the reporter and effector vectors. C: The coexpression of reporter and effector vector in tobacco leaves. pCAM-C, -G -A, -CM2: three tandem of C-, G-, A-box, or their mutant CM2 was respectively fused to a minimal promoter (-46 to +1) to drive GUS. pROKII-ThbZIP1: the ORF of ThbZIP1 was under the control of CaMV 35S promoter. D: GUS activity assay of the coexpression of reporter and effector plasmid. CaMV35S: The transformation of pCAMBIA1301 alone (positive control). The transformation of the reporter plasmids alone were used as negative controls. All assays were repeated three times and error bars indicate SE.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3852707&req=5

Figure 3: Analyses of the bindings of ThbZIP1 to C-, G- and A-box. A: (a-d): Analysis of the bindings of ThbZIP1 to C-, G-, A-box and their mutated sequences by yeast one-hybrid analysis. The yeast cells were grown on different intensities of selective dropout medias: SD/- Trp-Leu/-His (TDO) + 3-AT (3-AT concentrations, a: 30 mM, b: 40 mM, c: 50 mM, d: 60 mM). B: A diagram of the reporter and effector vectors. C: The coexpression of reporter and effector vector in tobacco leaves. pCAM-C, -G -A, -CM2: three tandem of C-, G-, A-box, or their mutant CM2 was respectively fused to a minimal promoter (-46 to +1) to drive GUS. pROKII-ThbZIP1: the ORF of ThbZIP1 was under the control of CaMV 35S promoter. D: GUS activity assay of the coexpression of reporter and effector plasmid. CaMV35S: The transformation of pCAMBIA1301 alone (positive control). The transformation of the reporter plasmids alone were used as negative controls. All assays were repeated three times and error bars indicate SE.
Mentions: The ThbZIP1 can bind to C-, G- and A-box sequences, but binds more strongly to C-box, followed by G-box and lastly A-box motifs (Figure 3A). Among the four mutants of ACGT elements, ThbZIP1 fails to bind to the CM2 mutant, but is able to bind to the CM1, CM3 and CM4 to some extent. Furthermore, ThbZIP1 is able to bind to CM3 more strongly than CM1 and CM4 (Figure 3A). To confirm these interactions, the effector construct (pROKII–ThbZIP1) and reporter plasmids (pCAM-C-box, -G-box or -A-box) were coexpressed in the tobacco leaves. Consistent with the yeast one-hybrid analyses, GUS staining and activity measurements both showed that ThbZIP1 can bind more strongly to C-box sequences, followed by G-box and A-box (Figure 3C, D).

Bottom Line: Two MYCs were found to bind to E-box, in the promoter of ThbZIP1 to activate its expression.Compared with wild-type (Col-0) Arabidopsis, transgenic plants expressing ThbZIP1 had an increased tolerance to drought and salt, but had an increased sensitivity to ABA during seed germination and root growth; meanwhile, ROS level, cell death and water loss rate in transgenic plants were significantly reduced.Based on these data, we suggest that ThbZIP1 confers abiotic stress tolerance through activating stress tolerance genes to modulate ROS scavenging ability and other physiological changes involved in stress tolerance, and plays an important role in the ABA-mediated stress response of T. hispida.

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Laboratory of Tree Genetics and Breeding (Northeast Forestry University), 26 Hexing Road, 150040 Harbin, China. ychngwang@yahoo.com.

ABSTRACT

Background: Tamarix spp. are woody halophyte, which are very tolerant to abiotic stresses such as salinity and drought, but little is known about their specific stress response systems. Basic leucine zipper proteins (bZIPs) play important roles in the ability of plants to withstand adverse environmental conditions. However, their exact roles in abiotic stress tolerance are still not fully known. In the current study, we functionally characterized a bZIP gene (ThbZIP1) from Tamarix hispida in response to abiotic stresses.

Results: We addressed the regulatory network of ThbZIP1 in three levels, i.e. its upstream regulators, the cis-acting elements recognized by ThbZIP1, and its downstream target genes. Two MYCs were found to bind to E-box, in the promoter of ThbZIP1 to activate its expression. Expression of ThbZIP1 is induced by ABA, salt, drought, methyl viologen and cold. ThbZIP1 can specifically bind to ACGT elements, with the highest binding affinity to the C-box, followed by the G-box and lastly the A-box. Compared with wild-type (Col-0) Arabidopsis, transgenic plants expressing ThbZIP1 had an increased tolerance to drought and salt, but had an increased sensitivity to ABA during seed germination and root growth; meanwhile, ROS level, cell death and water loss rate in transgenic plants were significantly reduced. Microarray analyses showed that many ROS scavenging genes were up-regulated by ThbZIP1 under salt stress conditions.

Conclusions: Based on these data, we suggest that ThbZIP1 confers abiotic stress tolerance through activating stress tolerance genes to modulate ROS scavenging ability and other physiological changes involved in stress tolerance, and plays an important role in the ABA-mediated stress response of T. hispida.

Show MeSH
Related in: MedlinePlus