Early signaling events in response to environmental stress


To better understand how early signaling events mediated by secondary messengers and plant hormones affect the acclimation to stress conditions in potato, potato lines were developed for the measurement of Ca2+ transients, the cytosolic redox status and the hormones ABA and jasmonate.



In a collaboration between the University of Bonn, the FAU Erlangen and Durham University, aequorin-based sensor lines of potato and Arabidopsis was used to analyse and compare Ca2+ transients in response to different abiotic and biotic stimuli using soil grown plants. The analysis revealed differences in the kinetics and amplitude of Ca2+ transients between both species, implying species-specific sensitivity for different stress conditions.

To further elucidate the Ca2+ responses with a better resolution in regards to specific tissues and even specific cells, a potato line carrying the fluorescence-based genetically encoded Ca2+ indicator GCaMP3 (StGCaMP3) was generated. The indicator localizes in the cytosol and nucleus and due to the power of regions-of-interest provide by high-resolution microscopes, changes in the Ca2+ levels of both compartments can be analysed separately. Changes in GCaMP3 fluorescence in response to external application of ATP (Figure 1A) and stress-induced Ca2+ waves going through the stolon tissue can be observed using a fluorescence microscope (Figure 1B).

This new sensor line will become part of our ongoing studies on early signaling events in Désirée under drought/heat and flooding stress to ultimately generate a detailed timeline and comprehensive event map of early stress responses. Moreover, they will be used to address questions regarding Ca2+ signaling in stolon development and cell specific stress response, e.g. in stomata.

Figure 1: A) ATP induced Ca2+transient observed via changes in GCaMP3 fluorescence. B) Still pictures from three different time points of a video recording of stress-induced Ca2+ waves observed in the StGCaMP3 line using a fluorescence microscope.