Cold-induced cytosolic free calcium ion concentration changes in wheat.
Relatively little is known about changes in the cytosolic free calcium ion concentration ([Ca(2+)](c)) in monocotyledonous plants. Therefore, we produced transgenic winter wheat lines stably expressing the calcium-sensitive photoprotein aequorin constitutively in the cytosol. [Ca(2+)](c) was detected in vivo by luminometry, and [Ca(2+)](c) elevations were imaged at video rate. Experiments with the transgenic seedlings focused on potential changes in [Ca(2+)](c) during cold exposure. Temperature-induced changes in [Ca(2+)](c) were found to be more dependent on the change in temperature (dT dt(-1)) than on the absolute value of temperature. [Ca(2+)](c) increased only at cooling rates higher than 8 degrees Cmin(-1), indicating that an overall cellular [Ca(2+)](c) increase is of minor relevance as a signal for cold acclimation in wheat under ecological conditions. The results are discussed with regard to the so-called 'calcium signature hypothesis'.
Nagel-Volkmann
J
J
Universität Hamburg, Biozentrum Klein Flottbek, Ohnhorststrasse 18, D-22609 Hamburg, Germany. juergen.nagel-volkmann@rats-os.de
Plieth
C
C
Becker
D
D
Lüthen
H
H
Dörffling
K
K
D000331:Aequorin / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D003080:Cold Temperature; D003600:Cytosol / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000378:metabolism; D014908:Triticum / Q000378:metabolism*
D010940:Plant Proteins; D000331:Aequorin; D002118:Calcium