A cell surface receptor mediates extracellular Ca(2+) sensing in guard cells.
Extracellular Ca(2+) (Ca(2+)(o)) is required for various physiological and developmental processes in animals and plants. In response to varied Ca(2+)(o) levels, plants maintain relatively constant internal Ca(2+) content, suggesting a precise regulatory mechanism for Ca(2+) homeostasis. However, little is known about how plants monitor Ca(2+)(o) status and whether Ca(2+)(o)-sensing receptors exist. The effects of Ca(2+)(o) on guard cells in promoting stomatal closure by inducing increases in the concentration of cytosolic Ca(2+) ([Ca(2+)](i)) provide a clue to Ca(2+)(o) sensing. Here we have used a functional screening assay in mammalian cells to isolate an Arabidopsis complementary DNA clone encoding a Ca(2+)-sensing receptor, CAS. CAS is localized to the plasma membrane, exhibits low-affinity/high-capacity Ca(2+) binding, and mediates Ca(2+)(o)-induced [Ca(2+)](i) increases. CAS is expressed predominantly in the shoot, including guard cells. Repression of CAS disrupts Ca(2+)(o) signalling in guard cells, and impairs bolting (swift upward growth at the transition to seed production) in response to Ca(2+) deficiency, so we conclude that CAS may be a primary transducer of Ca(2+)(o) in plants.
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Related Subject Headings
- Receptors, Cell Surface
- Receptors, Calcium-Sensing
- RNA, Messenger
- Protein Transport
- Molecular Sequence Data
- Humans
- Homeostasis
- Genes, Plant
- General Science & Technology
- Gene Expression Profiling
Citation
Published In
DOI
EISSN
ISSN
Publication Date
Volume
Issue
Start / End Page
Related Subject Headings
- Receptors, Cell Surface
- Receptors, Calcium-Sensing
- RNA, Messenger
- Protein Transport
- Molecular Sequence Data
- Humans
- Homeostasis
- Genes, Plant
- General Science & Technology
- Gene Expression Profiling