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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

[Ca2+]ext-induced stomatal closure in mutant plants and transgenic lines.Stomatal aperture was calculated as the ratio of stomatal width to stomatal length. Each value is the mean of three independent measurements, and the error bars indicate SD. Significant differences from Col-0 control plants (No treatment, 2 mM CaCl2 treatment) after drought treatment were determined by the t-test. * p < 0.05 and ** p < 0.01.
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pone.0131272.g003: [Ca2+]ext-induced stomatal closure in mutant plants and transgenic lines.Stomatal aperture was calculated as the ratio of stomatal width to stomatal length. Each value is the mean of three independent measurements, and the error bars indicate SD. Significant differences from Col-0 control plants (No treatment, 2 mM CaCl2 treatment) after drought treatment were determined by the t-test. * p < 0.05 and ** p < 0.01.

Mentions: PCR was used to amplify Hyg and OsCAS genes to identify transgenic plants. Positive plants showed both the 916-bp band of the Hyg gene and the 1164-bp band of the OsCAS gene. However, Col-0 and Salk did not show these bands. Finally, four lines (L1, L2, L3, and L4) were identified as positive OsCAS transgenic plants (S2 Fig). To further verify the OsCAS expression in transgenic plants, qRT analysis was performed. qRT analysis demonstrated that the OsCAS gene was overexpressed in the transgenic plants (Fig 2A). To examine the role of OsCAS in transgenic plants, we analyzed stomatal movement. Interestingly, we found that OsCAS overexpression in the transgenic plants promoted stomatal closure in the absence of external Ca2+ (Fig 3). These results indicated that OsCAS was successfully transformed and expressed in the mutants. For the sake of efficiency, we selected L3 as the representative of transgenic plants in the next experiment.


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

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

[Ca2+]ext-induced stomatal closure in mutant plants and transgenic lines.Stomatal aperture was calculated as the ratio of stomatal width to stomatal length. Each value is the mean of three independent measurements, and the error bars indicate SD. Significant differences from Col-0 control plants (No treatment, 2 mM CaCl2 treatment) after drought treatment were determined by the t-test. * p < 0.05 and ** p < 0.01.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0131272.g003: [Ca2+]ext-induced stomatal closure in mutant plants and transgenic lines.Stomatal aperture was calculated as the ratio of stomatal width to stomatal length. Each value is the mean of three independent measurements, and the error bars indicate SD. Significant differences from Col-0 control plants (No treatment, 2 mM CaCl2 treatment) after drought treatment were determined by the t-test. * p < 0.05 and ** p < 0.01.
Mentions: PCR was used to amplify Hyg and OsCAS genes to identify transgenic plants. Positive plants showed both the 916-bp band of the Hyg gene and the 1164-bp band of the OsCAS gene. However, Col-0 and Salk did not show these bands. Finally, four lines (L1, L2, L3, and L4) were identified as positive OsCAS transgenic plants (S2 Fig). To further verify the OsCAS expression in transgenic plants, qRT analysis was performed. qRT analysis demonstrated that the OsCAS gene was overexpressed in the transgenic plants (Fig 2A). To examine the role of OsCAS in transgenic plants, we analyzed stomatal movement. Interestingly, we found that OsCAS overexpression in the transgenic plants promoted stomatal closure in the absence of external Ca2+ (Fig 3). These results indicated that OsCAS was successfully transformed and expressed in the mutants. For the sake of efficiency, we selected L3 as the representative of transgenic plants in the next experiment.

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