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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.

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Comparisons of germination rate and growth between ThbZIP1 transformed and Col-0 plants. A: RT-PCR detected the expression of exogenous ThbZIP1 in transgenic plants. B: The growth of ThbZIP1 transformed and Col-0 plants under salt, drought, ABA and normal growth conditions; a, b, c, plants under the conditions of normal growth (a), salt (b), drought (c), and ABA (d). C: A comparison of the seed germination rates between ThbZIP1 transformed and Col-0 plants under normal growth condition (a), salt (b), drought (c) and ABA (d) stress conditions; D: An analysis of root growth (a, b, c), fresh weight (d, e, f) and germination rate (g, h, i) of ThbZIP1 transformed and Col-0 plants under salt, drought and ABA stress conditions. Data are means ± SD from three independent experiments. * Significant (t test, P < 0.05) difference compared with Col-0 plants.
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Figure 4: Comparisons of germination rate and growth between ThbZIP1 transformed and Col-0 plants. A: RT-PCR detected the expression of exogenous ThbZIP1 in transgenic plants. B: The growth of ThbZIP1 transformed and Col-0 plants under salt, drought, ABA and normal growth conditions; a, b, c, plants under the conditions of normal growth (a), salt (b), drought (c), and ABA (d). C: A comparison of the seed germination rates between ThbZIP1 transformed and Col-0 plants under normal growth condition (a), salt (b), drought (c) and ABA (d) stress conditions; D: An analysis of root growth (a, b, c), fresh weight (d, e, f) and germination rate (g, h, i) of ThbZIP1 transformed and Col-0 plants under salt, drought and ABA stress conditions. Data are means ± SD from three independent experiments. * Significant (t test, P < 0.05) difference compared with Col-0 plants.

Mentions: Nine independent T3 homozygous lines overexpressing ThbZIP1 were generated, and RT-PCR confirmed that the exogenous ThbZIP1 was expressed in the transgenic plants (Figure 4A). Two independent ThbZIP1 transgenic lines (b-2, b-8) were selected for further study. Under normal growth conditions, there was no difference in growth between Col-0 and transgenic plants (Figure 4B, C, D). However, the transgenic lines showed significant improved root growth and fresh weight under drought or salt stress as compared with wild-type (Col-0) plants. In addition, the ThbZIP1 transgenic plants exhibited an increase in seed germination under NaCl or Mannitol stress in comparison with Col-0 plants (Figure 4C, D). These results suggest that ThbZIP1 conferred an enhanced salt and drought tolerance to ThbZIP1 transformed plants.


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)

Comparisons of germination rate and growth between ThbZIP1 transformed and Col-0 plants. A: RT-PCR detected the expression of exogenous ThbZIP1 in transgenic plants. B: The growth of ThbZIP1 transformed and Col-0 plants under salt, drought, ABA and normal growth conditions; a, b, c, plants under the conditions of normal growth (a), salt (b), drought (c), and ABA (d). C: A comparison of the seed germination rates between ThbZIP1 transformed and Col-0 plants under normal growth condition (a), salt (b), drought (c) and ABA (d) stress conditions; D: An analysis of root growth (a, b, c), fresh weight (d, e, f) and germination rate (g, h, i) of ThbZIP1 transformed and Col-0 plants under salt, drought and ABA stress conditions. Data are means ± SD from three independent experiments. * Significant (t test, P < 0.05) difference compared with Col-0 plants.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 4: Comparisons of germination rate and growth between ThbZIP1 transformed and Col-0 plants. A: RT-PCR detected the expression of exogenous ThbZIP1 in transgenic plants. B: The growth of ThbZIP1 transformed and Col-0 plants under salt, drought, ABA and normal growth conditions; a, b, c, plants under the conditions of normal growth (a), salt (b), drought (c), and ABA (d). C: A comparison of the seed germination rates between ThbZIP1 transformed and Col-0 plants under normal growth condition (a), salt (b), drought (c) and ABA (d) stress conditions; D: An analysis of root growth (a, b, c), fresh weight (d, e, f) and germination rate (g, h, i) of ThbZIP1 transformed and Col-0 plants under salt, drought and ABA stress conditions. Data are means ± SD from three independent experiments. * Significant (t test, P < 0.05) difference compared with Col-0 plants.
Mentions: Nine independent T3 homozygous lines overexpressing ThbZIP1 were generated, and RT-PCR confirmed that the exogenous ThbZIP1 was expressed in the transgenic plants (Figure 4A). Two independent ThbZIP1 transgenic lines (b-2, b-8) were selected for further study. Under normal growth conditions, there was no difference in growth between Col-0 and transgenic plants (Figure 4B, C, D). However, the transgenic lines showed significant improved root growth and fresh weight under drought or salt stress as compared with wild-type (Col-0) plants. In addition, the ThbZIP1 transgenic plants exhibited an increase in seed germination under NaCl or Mannitol stress in comparison with Col-0 plants (Figure 4C, D). These results suggest that ThbZIP1 conferred an enhanced salt and drought tolerance to ThbZIP1 transformed plants.

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