Plant and Cell Physiology Supplement
Supplement to Plant and Cell Physiology Vol. 45
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Isolation and functional characterization of an Arabidopsis cDNA encoding a putative Ca2+-permeable stretch-activated channel
*Yuko NakagawaTakeshi KatagiriKazuo ShinozakiZhi QiAkio KishigamiTakuya FuruichiHitoshi TatsumiMasahiro SokabeShusei SatoTomohiko KatoSatoshi TabataItaru KojimaKazuko IidaMitsunobu IkedaTakuya YamanakaHidetoshi Iida
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Abstract
Stretch-activated (SA) channels are thought to be a candidate for sensors of mechanical stimuli. We isolated an Arabidopsis cDNA by functional complementation of yeast mutant defective in the MID1 gene encoding a putative Ca2+-permeable SA channel component. To investigate functions of the cDNA (named AtMID1A), we made transgenic plants overexpressing AtMID1A. The transgenic plants showed a dwarf phenotype. Increases in Ca2+ concentration in medium aggravated this phenotype, whereas decreases in Ca2+ concentration alleviated it. Hypotonic shock increased cytosolic free Ca2+ concentration ([Ca2+] cyt) higher in the transgenic plants than in control plants, as monitored with aequorin. The [Ca2+]cyt increase was inhibited by cation channel blockers and a Ca2+ chelator. Additionally, trinitrophenol, which presumably expands the outer lipid layer of the plasma membrane, also increased [Ca2+]cyt higher in the transgenic plants than in control plants. These data suggest that the AtMID1A product is a Ca2+-permeable SA channel.
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© 2004 by The Japanese Society of Plant Physiologists
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