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Expression of OsCAS (Calcium-Sensing Receptor) in an Arabidopsis Mutant Increases Drought Tolerance.

Zhao X, Xu M, Wei R, Liu Y - PLoS ONE (2015)

Bottom Line: With respect to chlorophyll fluorescence, the electron transport rate and effective PSII quantum yield decreased in all lines under drought stress; however, in the transgenic plants these two parameters changed fewer and were higher than those in wild-type and Salk plants.The above results suggest that the transgenic plants showed better resistance to drought stress by decreasing damage to the cell membrane, increasing the amount of osmoprotectants, and maintaining a relatively high photosynthetic capacity.In conclusion, OsCAS is an extracellular calcium-sensing receptor that helps to compensate for the absence of CaS in Arabidopsis and increases the drought stress tolerance of transgenic plants.

View Article: PubMed Central - PubMed

Affiliation: College of Life Science, Capital Normal University, Beijing, People's Republic of China.

ABSTRACT
The calcium-sensing receptor (CaS), which is localized in the chloroplasts, is a crucial regulator of extracellular calcium-induced stomatal closure in Arabidopsis. It has homologs in Oryza sativa and other plants. These sequences all have a rhodanese-like protein domain, which has been demonstrated to be associated with specific stress conditions. In this study, we cloned the Oryza sativa calcium-sensing receptor gene (OsCAS) and demonstrated that OsCAS could sense an increase of extracellular Ca2+ concentration and mediate an increase in cytosolic Ca2+ concentration. The OsCAS gene was transformed into an Arabidopsis CaS knockout mutant (Salk) and overexpressed in the transgenic plants. OsCAS promoted stomatal closure. We screened homozygous transgenic Arabidopsis plants and determined physiological indices such as the oxidative damage biomarker malondialdehyde (MDA), relative membrane permeability (RMP), proline content, and chlorophyll fluorescence parameters, after 21 days of drought treatment. Our results revealed lower RMP and MDA contents and a higher Proline content in transgenic Arabidopsis plants after drought stress, whereas the opposite was observed in Salk plants. With respect to chlorophyll fluorescence, the electron transport rate and effective PSII quantum yield decreased in all lines under drought stress; however, in the transgenic plants these two parameters changed fewer and were higher than those in wild-type and Salk plants. The quantum yield of regulated energy dissipation and nonregulated energy dissipation in PSII were higher in Salk plants, whereas these values were lower in the transgenic plants than in the wild type under drought stress. The above results suggest that the transgenic plants showed better resistance to drought stress by decreasing damage to the cell membrane, increasing the amount of osmoprotectants, and maintaining a relatively high photosynthetic capacity. In conclusion, OsCAS is an extracellular calcium-sensing receptor that helps to compensate for the absence of CaS in Arabidopsis and increases the drought stress tolerance of transgenic plants.

No MeSH data available.


Related in: MedlinePlus

Expression cloning of rice CaS and Arabidopsis CaS using calcium imaging.HEK293 cells were transiently transfected with empty vector, pcDNA3-CAS, or pcDNA3-OsCAS. The cytosolic Ca2+ status was analyzed using Fura-2-based Ca2+ imaging after treatment with 0.l mM and 2.5 mM extracellular Ca2+. Elevated relative calcium concentrations are indicated by an increased ratio of Fura-2 emission at 340 versus 380 nm wavelength excitation (see color bar). Arrows show cells with CICI (Ca2+o-induced [Ca2+]i increases).
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pone.0131272.g001: Expression cloning of rice CaS and Arabidopsis CaS using calcium imaging.HEK293 cells were transiently transfected with empty vector, pcDNA3-CAS, or pcDNA3-OsCAS. The cytosolic Ca2+ status was analyzed using Fura-2-based Ca2+ imaging after treatment with 0.l mM and 2.5 mM extracellular Ca2+. Elevated relative calcium concentrations are indicated by an increased ratio of Fura-2 emission at 340 versus 380 nm wavelength excitation (see color bar). Arrows show cells with CICI (Ca2+o-induced [Ca2+]i increases).

Mentions: HEK293 cells transiently transfected with vector alone (pCDNA3, Fig 1A) exhibited no response to extracellular Ca2+ increases from 0.1 to 2.5 mM. However, the rice CAS (Fig 1B) and Arabidopsis CAS (Fig 1C) were identified by marked increases in cytoplasmic calcium (arrowheads), which results in more cells sensitive to extracellular Ca2+.


Expression of OsCAS (Calcium-Sensing Receptor) in an Arabidopsis Mutant Increases Drought Tolerance.

Zhao X, Xu M, Wei R, Liu Y - PLoS ONE (2015)

Expression cloning of rice CaS and Arabidopsis CaS using calcium imaging.HEK293 cells were transiently transfected with empty vector, pcDNA3-CAS, or pcDNA3-OsCAS. The cytosolic Ca2+ status was analyzed using Fura-2-based Ca2+ imaging after treatment with 0.l mM and 2.5 mM extracellular Ca2+. Elevated relative calcium concentrations are indicated by an increased ratio of Fura-2 emission at 340 versus 380 nm wavelength excitation (see color bar). Arrows show cells with CICI (Ca2+o-induced [Ca2+]i increases).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4476762&req=5

pone.0131272.g001: Expression cloning of rice CaS and Arabidopsis CaS using calcium imaging.HEK293 cells were transiently transfected with empty vector, pcDNA3-CAS, or pcDNA3-OsCAS. The cytosolic Ca2+ status was analyzed using Fura-2-based Ca2+ imaging after treatment with 0.l mM and 2.5 mM extracellular Ca2+. Elevated relative calcium concentrations are indicated by an increased ratio of Fura-2 emission at 340 versus 380 nm wavelength excitation (see color bar). Arrows show cells with CICI (Ca2+o-induced [Ca2+]i increases).
Mentions: HEK293 cells transiently transfected with vector alone (pCDNA3, Fig 1A) exhibited no response to extracellular Ca2+ increases from 0.1 to 2.5 mM. However, the rice CAS (Fig 1B) and Arabidopsis CAS (Fig 1C) were identified by marked increases in cytoplasmic calcium (arrowheads), which results in more cells sensitive to extracellular Ca2+.

Bottom Line: With respect to chlorophyll fluorescence, the electron transport rate and effective PSII quantum yield decreased in all lines under drought stress; however, in the transgenic plants these two parameters changed fewer and were higher than those in wild-type and Salk plants.The above results suggest that the transgenic plants showed better resistance to drought stress by decreasing damage to the cell membrane, increasing the amount of osmoprotectants, and maintaining a relatively high photosynthetic capacity.In conclusion, OsCAS is an extracellular calcium-sensing receptor that helps to compensate for the absence of CaS in Arabidopsis and increases the drought stress tolerance of transgenic plants.

View Article: PubMed Central - PubMed

Affiliation: College of Life Science, Capital Normal University, Beijing, People's Republic of China.

ABSTRACT
The calcium-sensing receptor (CaS), which is localized in the chloroplasts, is a crucial regulator of extracellular calcium-induced stomatal closure in Arabidopsis. It has homologs in Oryza sativa and other plants. These sequences all have a rhodanese-like protein domain, which has been demonstrated to be associated with specific stress conditions. In this study, we cloned the Oryza sativa calcium-sensing receptor gene (OsCAS) and demonstrated that OsCAS could sense an increase of extracellular Ca2+ concentration and mediate an increase in cytosolic Ca2+ concentration. The OsCAS gene was transformed into an Arabidopsis CaS knockout mutant (Salk) and overexpressed in the transgenic plants. OsCAS promoted stomatal closure. We screened homozygous transgenic Arabidopsis plants and determined physiological indices such as the oxidative damage biomarker malondialdehyde (MDA), relative membrane permeability (RMP), proline content, and chlorophyll fluorescence parameters, after 21 days of drought treatment. Our results revealed lower RMP and MDA contents and a higher Proline content in transgenic Arabidopsis plants after drought stress, whereas the opposite was observed in Salk plants. With respect to chlorophyll fluorescence, the electron transport rate and effective PSII quantum yield decreased in all lines under drought stress; however, in the transgenic plants these two parameters changed fewer and were higher than those in wild-type and Salk plants. The quantum yield of regulated energy dissipation and nonregulated energy dissipation in PSII were higher in Salk plants, whereas these values were lower in the transgenic plants than in the wild type under drought stress. The above results suggest that the transgenic plants showed better resistance to drought stress by decreasing damage to the cell membrane, increasing the amount of osmoprotectants, and maintaining a relatively high photosynthetic capacity. In conclusion, OsCAS is an extracellular calcium-sensing receptor that helps to compensate for the absence of CaS in Arabidopsis and increases the drought stress tolerance of transgenic plants.

No MeSH data available.


Related in: MedlinePlus