Changes in Ca2+ levels inside a growing root as it experiences mechanical bending

This movie is of a region of the root of the plant Arabidopsis thaliana (mouse ear cress). The plant has been engineered to produce a fluorescent protein in the cytoplasm whose brightness chanes as the Ca2+ levels in the cytoplasm change. Images of the root were taken using a confocal microscope and then the converted to a measurement of Ca2+ and colour coded, where green is low and red high Ca2+ levels. The root was then bent to trigger mechanicaaly-related signaling events. The increase in Ca2+ in the stretched cells most likely refelcts activation of stretch-activated Ca2+ channels in the cell membrane leading to an influx of Ca2+. This Ca2+ then acts as a signal to alter cellullar events in these stretched cells to respond to this signal and alter root growth. Movie copyright Plant Physiology (151:1855-1866).

For more research into this response see:
Richter et al (2008) Plant Physiology 151:1855-1866

Monshausen and Gilroy (2009) Current Opinion in Plant Sciences 12:766–772