Abstract

In plants, rises in cytosolic Ca2+ concentration ([Ca2+]cyt) occur in response to both biotic and abiotic stimuli. These rises can, depending on the stimulus, display the form of a single transient or repetitive Ca2+ oscillations and are commonly designated as “Ca2+ signatures”. Generation and shaping of [Ca2+]cyt signatures depends on fine-tuning of Ca2+ influxes and effluxes occurring at both the plasma membrane (PM) and membranes of the different subcellular compartments. The opening of Ca2+-permeable influx channels in response to a stimulus will release Ca2+ into the cytosol and cause the generation of a Ca2+ spike, while activity of Ca2+ efflux transporters (H+-Ca2+ antiporters and Ca2+-ATPases) will return the [Ca2+]cyt to resting concentrations. In order to understand how the cytosolic Ca2+ dynamics are generated and shaped in different cell types, two issues need to be addressed: i) the study of how do organelles participate in these processes and ii) the possibility to perform single cell Ca2+ analyses in complex tissues and organs, in natural context and in close-to physiological conditions.

The seminar will present data about:

a) the in planta use of the genetically encoded FRET (Förster Resonance Energy Transfer)-based Ca2+ Cameleon sensor. Attention will be given to the developed Cameleon probes for the analyses of Ca2+ dynamics in several subcellular compartments;

b) development of a new microscopy solution, based on Selective Plane Illumination Microscopy (SPIM), for FRET -based Ca2+ imaging analyses in Arabidopsis root cells;

c) use of the presented technologies for the study of channels and pumps involved in the generation and regulation of cytosolic Ca2+ dynamics.