Plant Ca-ATPases: From biochemistry to signalling.

Calcium (Ca)-ATPases are ATP-dependent enzymes that transport Ca ions against their electrochemical gradient playing the fundamental biological function of keeping the free cytosolic Ca concentration in the submicromolar range to prevent cytotoxic effects. In plants, type IIB autoinhibited Ca-ATPases (ACAs) are localised both at the plasma membrane and at the endomembranes including endoplasmic reticulum (ER) and tonoplast and their activity is primarily regulated by Ca-dependent mechanisms. Instead, type IIA ER-type Ca-ATPases (ECAs) are present mainly at the ER and Golgi Apparatus membranes and are active at resting Ca.

Long-distance turgor pressure changes induce local activation of plant glutamate receptor-like channels.

In Arabidopsis thaliana, local wounding and herbivore feeding provoke leaf-to-leaf propagating Ca waves that are dependent on the activity of members of the glutamate receptor-like channels (GLRs). In systemic tissues, GLRs are needed to sustain the synthesis of jasmonic acid (JA) with the subsequent activation of JA-dependent signaling response required for the plant acclimation to the perceived stress. Even though the role of GLRs is well established, the mechanism through which they are activated remains unclear.

Signaling by plant glutamate receptor-like channels: What else!

Plant glutamate receptor-like channels (GLRs) are transmembrane proteins that allow the movement of several ions across membranes. In the model plant Arabidopsis, there are 20 GLR isoforms grouped in three clades and, since their discovery, it was hypothesized that GLRs were mainly involved in signaling processes. Indeed, in the last years, several pieces of evidence demonstrate different signaling roles played by GLRs, related to pollen development, sexual reproduction, chemotaxis, root development, regulation of stomatal aperture, and response to pathogens.

Simultaneous imaging of ER and cytosolic Ca2+ dynamics reveals long-distance ER Ca2+ waves in plants.

Calcium ions (Ca2+) play a key role in cell signaling across organisms. In plants, a plethora of environmental and developmental stimuli induce specific Ca2+ increases in the cytosol as well as in different cellular compartments including the endoplasmic reticulum (ER). The ER represents an intracellular Ca2+ store that actively accumulates Ca2+ taken up from the cytosol.

The signatures of organellar calcium.

Recent insights about the transport mechanisms involved in the in and out of calcium ions in plant organelles, and their role in the regulation of cytosolic calcium homeostasis in different signaling pathways.