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Anna Amtmann - One of the best experts on this subject based on the ideXlab platform.
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thellungiella Halophila a salt tolerant relative of arabidopsis thaliana has specific root ion channel features supporting k na homeostasis under salinity stress
Plant Journal, 2006Co-Authors: Vadim Volkov, Anna AmtmannAbstract:Summary Thellungiella Halophila is a salt-tolerant relative of Arabidopsis thaliana with high genetic and morphological similarity. In a saline environment, T. Halophila accumulates less sodium and retains more potassium than A. thaliana. Detailed electrophysiological comparison of ion currents in roots of both species showed that, unlike A. thaliana, T. Halophila exhibits high potassium/sodium selectivity of the instantaneous current. This current differs in its pharmacological profile from the current through inward- and outward-rectifying K+ channels insofar as it is insensitive to Cs+ and TEA+, but resembles voltage-independent channels of glycophytes as it is inhibited by external Ca2+. Addition of Cs+ and TEA+ to the growth medium confirmed the key role of the instantaneous current in whole-plant sodium accumulation. A negative shift in the reversal potential of the instantaneous current under high-salt conditions was essential for decreasing sodium influx to twofold lower than the corresponding value in A. thaliana. The lower overall sodium permeability of the T. Halophila root plasma membrane resulted in a smaller membrane depolarization during salt exposure, thus allowing the cells to maintain their driving force for potassium uptake. Our data provide quantitative evidence that specific features of ion channels lead to superior sodium/potassium homeostasis in a halophyte compared with a closely related glycophyte.
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low unidirectional sodium influx into root cells restricts net sodium accumulation in thellungiella Halophila a salt tolerant relative of arabidopsis thaliana
Journal of Experimental Botany, 2006Co-Authors: Bo Wang, Romola Davenport, Vadim Volkov, Anna AmtmannAbstract:Thellungiella halophlla is a useful model species for research into plant salt tolerance. It is closely related to Arabidopsis thaliana, but shows considerably higher salt tolerance. Comparative analysis of ion homeostasis in the two species allows the identification of ion transport pathways that are critical for salt tolerance and provides the basis for future studies into their molecular features. Previous studies indicated that salt tolerance in T. Halophila is accompanied by low accumulation of Na in the leaves. Kinetic analysis of net ion uptake over three days confirmed lower Na uptake and K loss in T. Halophila compared with A. thaliana. Differential net Na uptake rates were still apparent after 6 weeks of salt treatment. To assess the contribution of unidirectional Na fluxes to net Na uptake, kinetic studies of 22 Na fluxes were carried out in both species. The results show that unidirectional root Na influx is significantly lower in salt-grown T. Halophila plants than in A. thaliana exposed to the same level of salinity (100 mM). Quantitative comparison of unidirectional influx and net Na accumulation suggests that both species operate efficient Na efflux, which partly compensates for Na influx. Kinetic analysis of 22 Na efflux indicated higher root Na efflux in A. thaliana than in T. Halophila. Thus A. thaliana appears to spend more energy on Na export while nevertheless accumulating more Na than T. Halophila. It is proposed that limitation of Na influx is the main mechanism by which T. Halophila secures low net Na accumulation in saline conditions. This strategy provides the basis for a positive balance between growth and net Na uptake rates, which is essential for survival in high salt.
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thellungiella Halophila a salt tolerant relative of arabidopsis thaliana possesses effective mechanisms to discriminate between potassium and sodium
Plant Cell and Environment, 2004Co-Authors: Vadim Volkov, Bo Wang, P J Dominy, Wieland Fricke, Anna AmtmannAbstract:Thellungiella Halophila is a salt-tolerant close relative of Arabidopsis thaliana. Significant mRNA similarity was confirmed by hybridization of T. Halophila mRNA with the A. thaliana GeneChip ATH1. To establish a platform for future molecular comparison of the two species several physiological mechanisms, which may confer high salt tolerance to T. Halophila, were investigated. Determination of ion content in shoots and roots of A. thaliana and T. Halophila indicated different strategies of ion uptake and translocation from root to shoot in the two species. During salt stress T. Halophila accumulated less sodium than A. thaliana. Tissue concentrations of sodium and potassium showed negative correlation in A. thaliana but not in T. Halophila. Electrophysiological experiments proved high potassium/sodium selectivity of root plasma membrane channels in T. Halophila. In particular, voltage-independent currents were more selective for potassium in T. Halophila than in A. thaliana. Single cell sampling of T. Halophila leaves during salt exposure revealed increased concentrations of sodium and decreased concentrations of potassium in epidermal cells suggesting that this cell type could function to ensure storage of sodium and exchange of potassium with the rest of leaf. Application of salt resulted in a sharp drop of transpiration in A. thaliana. By contrast, transpiration in T. Halophila responded more slowly and was only slightly inhibited by salt treatment, thus maintaining high water uptake and ion transport.
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Thellungiella Halophila, a salt‐tolerant relative of Arabidopsis thaliana, possesses effective mechanisms to discriminate between potassium and sodium
Plant Cell and Environment, 2004Co-Authors: Vadim Volkov, P J Dominy, Wieland Fricke, B. Wang, Anna AmtmannAbstract:Thellungiella Halophila is a salt-tolerant close relative of Arabidopsis thaliana. Significant mRNA similarity was confirmed by hybridization of T. Halophila mRNA with the A. thaliana GeneChip ATH1. To establish a platform for future molecular comparison of the two species several physiological mechanisms, which may confer high salt tolerance to T. Halophila, were investigated. Determination of ion content in shoots and roots of A. thaliana and T. Halophila indicated different strategies of ion uptake and translocation from root to shoot in the two species. During salt stress T. Halophila accumulated less sodium than A. thaliana. Tissue concentrations of sodium and potassium showed negative correlation in A. thaliana but not in T. Halophila. Electrophysiological experiments proved high potassium/sodium selectivity of root plasma membrane channels in T. Halophila. In particular, voltage-independent currents were more selective for potassium in T. Halophila than in A. thaliana. Single cell sampling of T. Halophila leaves during salt exposure revealed increased concentrations of sodium and decreased concentrations of potassium in epidermal cells suggesting that this cell type could function to ensure storage of sodium and exchange of potassium with the rest of leaf. Application of salt resulted in a sharp drop of transpiration in A. thaliana. By contrast, transpiration in T. Halophila responded more slowly and was only slightly inhibited by salt treatment, thus maintaining high water uptake and ion transport.
Vadim Volkov - One of the best experts on this subject based on the ideXlab platform.
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thellungiella Halophila a salt tolerant relative of arabidopsis thaliana has specific root ion channel features supporting k na homeostasis under salinity stress
Plant Journal, 2006Co-Authors: Vadim Volkov, Anna AmtmannAbstract:Summary Thellungiella Halophila is a salt-tolerant relative of Arabidopsis thaliana with high genetic and morphological similarity. In a saline environment, T. Halophila accumulates less sodium and retains more potassium than A. thaliana. Detailed electrophysiological comparison of ion currents in roots of both species showed that, unlike A. thaliana, T. Halophila exhibits high potassium/sodium selectivity of the instantaneous current. This current differs in its pharmacological profile from the current through inward- and outward-rectifying K+ channels insofar as it is insensitive to Cs+ and TEA+, but resembles voltage-independent channels of glycophytes as it is inhibited by external Ca2+. Addition of Cs+ and TEA+ to the growth medium confirmed the key role of the instantaneous current in whole-plant sodium accumulation. A negative shift in the reversal potential of the instantaneous current under high-salt conditions was essential for decreasing sodium influx to twofold lower than the corresponding value in A. thaliana. The lower overall sodium permeability of the T. Halophila root plasma membrane resulted in a smaller membrane depolarization during salt exposure, thus allowing the cells to maintain their driving force for potassium uptake. Our data provide quantitative evidence that specific features of ion channels lead to superior sodium/potassium homeostasis in a halophyte compared with a closely related glycophyte.
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low unidirectional sodium influx into root cells restricts net sodium accumulation in thellungiella Halophila a salt tolerant relative of arabidopsis thaliana
Journal of Experimental Botany, 2006Co-Authors: Bo Wang, Romola Davenport, Vadim Volkov, Anna AmtmannAbstract:Thellungiella halophlla is a useful model species for research into plant salt tolerance. It is closely related to Arabidopsis thaliana, but shows considerably higher salt tolerance. Comparative analysis of ion homeostasis in the two species allows the identification of ion transport pathways that are critical for salt tolerance and provides the basis for future studies into their molecular features. Previous studies indicated that salt tolerance in T. Halophila is accompanied by low accumulation of Na in the leaves. Kinetic analysis of net ion uptake over three days confirmed lower Na uptake and K loss in T. Halophila compared with A. thaliana. Differential net Na uptake rates were still apparent after 6 weeks of salt treatment. To assess the contribution of unidirectional Na fluxes to net Na uptake, kinetic studies of 22 Na fluxes were carried out in both species. The results show that unidirectional root Na influx is significantly lower in salt-grown T. Halophila plants than in A. thaliana exposed to the same level of salinity (100 mM). Quantitative comparison of unidirectional influx and net Na accumulation suggests that both species operate efficient Na efflux, which partly compensates for Na influx. Kinetic analysis of 22 Na efflux indicated higher root Na efflux in A. thaliana than in T. Halophila. Thus A. thaliana appears to spend more energy on Na export while nevertheless accumulating more Na than T. Halophila. It is proposed that limitation of Na influx is the main mechanism by which T. Halophila secures low net Na accumulation in saline conditions. This strategy provides the basis for a positive balance between growth and net Na uptake rates, which is essential for survival in high salt.
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thellungiella Halophila a salt tolerant relative of arabidopsis thaliana possesses effective mechanisms to discriminate between potassium and sodium
Plant Cell and Environment, 2004Co-Authors: Vadim Volkov, Bo Wang, P J Dominy, Wieland Fricke, Anna AmtmannAbstract:Thellungiella Halophila is a salt-tolerant close relative of Arabidopsis thaliana. Significant mRNA similarity was confirmed by hybridization of T. Halophila mRNA with the A. thaliana GeneChip ATH1. To establish a platform for future molecular comparison of the two species several physiological mechanisms, which may confer high salt tolerance to T. Halophila, were investigated. Determination of ion content in shoots and roots of A. thaliana and T. Halophila indicated different strategies of ion uptake and translocation from root to shoot in the two species. During salt stress T. Halophila accumulated less sodium than A. thaliana. Tissue concentrations of sodium and potassium showed negative correlation in A. thaliana but not in T. Halophila. Electrophysiological experiments proved high potassium/sodium selectivity of root plasma membrane channels in T. Halophila. In particular, voltage-independent currents were more selective for potassium in T. Halophila than in A. thaliana. Single cell sampling of T. Halophila leaves during salt exposure revealed increased concentrations of sodium and decreased concentrations of potassium in epidermal cells suggesting that this cell type could function to ensure storage of sodium and exchange of potassium with the rest of leaf. Application of salt resulted in a sharp drop of transpiration in A. thaliana. By contrast, transpiration in T. Halophila responded more slowly and was only slightly inhibited by salt treatment, thus maintaining high water uptake and ion transport.
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Thellungiella Halophila, a salt‐tolerant relative of Arabidopsis thaliana, possesses effective mechanisms to discriminate between potassium and sodium
Plant Cell and Environment, 2004Co-Authors: Vadim Volkov, P J Dominy, Wieland Fricke, B. Wang, Anna AmtmannAbstract:Thellungiella Halophila is a salt-tolerant close relative of Arabidopsis thaliana. Significant mRNA similarity was confirmed by hybridization of T. Halophila mRNA with the A. thaliana GeneChip ATH1. To establish a platform for future molecular comparison of the two species several physiological mechanisms, which may confer high salt tolerance to T. Halophila, were investigated. Determination of ion content in shoots and roots of A. thaliana and T. Halophila indicated different strategies of ion uptake and translocation from root to shoot in the two species. During salt stress T. Halophila accumulated less sodium than A. thaliana. Tissue concentrations of sodium and potassium showed negative correlation in A. thaliana but not in T. Halophila. Electrophysiological experiments proved high potassium/sodium selectivity of root plasma membrane channels in T. Halophila. In particular, voltage-independent currents were more selective for potassium in T. Halophila than in A. thaliana. Single cell sampling of T. Halophila leaves during salt exposure revealed increased concentrations of sodium and decreased concentrations of potassium in epidermal cells suggesting that this cell type could function to ensure storage of sodium and exchange of potassium with the rest of leaf. Application of salt resulted in a sharp drop of transpiration in A. thaliana. By contrast, transpiration in T. Halophila responded more slowly and was only slightly inhibited by salt treatment, thus maintaining high water uptake and ion transport.
Meiru Li - One of the best experts on this subject based on the ideXlab platform.
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establishment of an efficient agrobacterium tumefaciens mediated leaf disc transformation of thellungiella Halophila
Plant Cell Reports, 2007Co-Authors: Hongqing Li, Jie Xu, Lei Chen, Meiru LiAbstract:Thellungiella Halophila is a salt-tolerant close relative of Arabidopsis, which is adopted as a halophytic model for stress tolerance research. We established an Agrobacterium tumefaciens-mediated transformation procedure for T. Halophila. Leaf explants of T. Halophila were incubated with A. tumefaciens strain EHA105 containing a binary vector pCAMBIA1301 with the hpt gene as a selectable marker for hygromycin resistance and an intron-containing β-glucuronidase gene as a reporter gene. Following co-cultivation, leaf explants were cultured on selective medium containing 10 mg l−1 hygromycin and 500 mg l−1 cefotaxime. Hygromycin-resistant calluses were induced from the leaf explants after 3 weeks. Shoot regeneration was achieved after transferring the calluses onto fresh medium of the same composition. Finally, the shoots were rooted on half strength MS basal medium supplemented with 10 mg l−1 hygromycin. Incorporation and expression of the transgenes were confirmed by PCR, Southern blot analysis and GUS histochemical assay. Using this protocol, transgenic T. Halophila plants can be obtained in approximately 2 months with a high transformation frequency of 26%.
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establishment of an efficient agrobacterium tumefaciens mediated leaf disc transformation of thellungiella Halophila
Plant Cell Reports, 2007Co-Authors: Hongqing Li, Jie Xu, Lei Chen, Meiru LiAbstract:Thellungiella Halophila is a salt-tolerant close relative of Arabidopsis, which is adopted as a halophytic model for stress tolerance research. We established an Agrobacterium tumefaciens-mediated transformation procedure for T. Halophila. Leaf explants of T. Halophila were incubated with A. tumefaciens strain EHA105 containing a binary vector pCAMBIA1301 with the hpt gene as a selectable marker for hygromycin resistance and an intron-containing β-glucuronidase gene as a reporter gene. Following co-cultivation, leaf explants were cultured on selective medium containing 10 mg l−1 hygromycin and 500 mg l−1 cefotaxime. Hygromycin-resistant calluses were induced from the leaf explants after 3 weeks. Shoot regeneration was achieved after transferring the calluses onto fresh medium of the same composition. Finally, the shoots were rooted on half strength MS basal medium supplemented with 10 mg l−1 hygromycin. Incorporation and expression of the transgenes were confirmed by PCR, Southern blot analysis and GUS histochemical assay. Using this protocol, transgenic T. Halophila plants can be obtained in approximately 2 months with a high transformation frequency of 26%.
Li Xinrong - One of the best experts on this subject based on the ideXlab platform.
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Effect of Salt Stress on Ultrastructure of Thellungiella Halophila Suspension-cultured Cells
Journal of Desert Research, 2011Co-Authors: Li XinrongAbstract:Thellungiella Halophila suspension-cultured cells were used to establish a 'cell culture/salt stress' system,and electronic transmission microscope was used to examine ultrastructural changes of Thellungiella Halophila cells.Organelles remained normal structures in untreated cells,while the plasma membrane began to detach from the cell wall and the cytoplasm appeared electron-opaque when cells were stressed under 300 mM NaCl for 6 hours.The plasma membrane retracted apparently from the cell wall after salt treatment for 12 hours.The number of mitochondria increased quickly and mitochondria were frequently crescent with illegible cristae at this time.Golgi body lost its normal morphology and became loose with small secretion vesicles budding from the trans end.We also found the presence of autophagic vacuoles in salt stressed cells.These results indicate that Thellungiella Halophila suspension-cultured cells can tolerate high salinity stress(300 mM NaCl) for a short time,while severe salt stress(300 mM NaCl for 12 h) leads to the impairment of cell with apparent ultrastructural changes.We suggest that autophagy may play an important role in Thellungiella Halophila cells in response to salt stress.
Hongqing Li - One of the best experts on this subject based on the ideXlab platform.
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establishment of an efficient agrobacterium tumefaciens mediated leaf disc transformation of thellungiella Halophila
Plant Cell Reports, 2007Co-Authors: Hongqing Li, Jie Xu, Lei Chen, Meiru LiAbstract:Thellungiella Halophila is a salt-tolerant close relative of Arabidopsis, which is adopted as a halophytic model for stress tolerance research. We established an Agrobacterium tumefaciens-mediated transformation procedure for T. Halophila. Leaf explants of T. Halophila were incubated with A. tumefaciens strain EHA105 containing a binary vector pCAMBIA1301 with the hpt gene as a selectable marker for hygromycin resistance and an intron-containing β-glucuronidase gene as a reporter gene. Following co-cultivation, leaf explants were cultured on selective medium containing 10 mg l−1 hygromycin and 500 mg l−1 cefotaxime. Hygromycin-resistant calluses were induced from the leaf explants after 3 weeks. Shoot regeneration was achieved after transferring the calluses onto fresh medium of the same composition. Finally, the shoots were rooted on half strength MS basal medium supplemented with 10 mg l−1 hygromycin. Incorporation and expression of the transgenes were confirmed by PCR, Southern blot analysis and GUS histochemical assay. Using this protocol, transgenic T. Halophila plants can be obtained in approximately 2 months with a high transformation frequency of 26%.
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establishment of an efficient agrobacterium tumefaciens mediated leaf disc transformation of thellungiella Halophila
Plant Cell Reports, 2007Co-Authors: Hongqing Li, Jie Xu, Lei Chen, Meiru LiAbstract:Thellungiella Halophila is a salt-tolerant close relative of Arabidopsis, which is adopted as a halophytic model for stress tolerance research. We established an Agrobacterium tumefaciens-mediated transformation procedure for T. Halophila. Leaf explants of T. Halophila were incubated with A. tumefaciens strain EHA105 containing a binary vector pCAMBIA1301 with the hpt gene as a selectable marker for hygromycin resistance and an intron-containing β-glucuronidase gene as a reporter gene. Following co-cultivation, leaf explants were cultured on selective medium containing 10 mg l−1 hygromycin and 500 mg l−1 cefotaxime. Hygromycin-resistant calluses were induced from the leaf explants after 3 weeks. Shoot regeneration was achieved after transferring the calluses onto fresh medium of the same composition. Finally, the shoots were rooted on half strength MS basal medium supplemented with 10 mg l−1 hygromycin. Incorporation and expression of the transgenes were confirmed by PCR, Southern blot analysis and GUS histochemical assay. Using this protocol, transgenic T. Halophila plants can be obtained in approximately 2 months with a high transformation frequency of 26%.
