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 tines stably expressing the calcium-sensitive photoprotein aequorin constitutively in the cytosol. [Ca(2+)](c) was detected in vivo by lurminometry, 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 coating rates higher than 8 degrees C min(-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'. (C) 2009 Elsevier GmbH. All rights reserved.