{Reference Type}: Journal Article
{Title}: Light-gated channelrhodopsin sparks proton-induced calcium release in guard cells.
{Author}: Huang S;Shen L;Roelfsema MRG;Becker D;Hedrich R;
{Journal}: Science
{Volume}: 382
{Issue}: 6676
{Year}: 2023 12 15
{Factor}: 63.714
{DOI}: 10.1126/science.adj9696
{Abstract}: Although there has been long-standing recognition that stimuli-induced cytosolic pH alterations coincide with changes in calcium ion (Ca2+) levels, the interdependence between protons (H+) and Ca2+ remains poorly understood. We addressed this topic using the light-gated channelrhodopsin HcKCR2 from the pseudofungus Hyphochytrium catenoides, which operates as a H+ conductive, Ca2+ impermeable ion channel on the plasma membrane of plant cells. Light activation of HcKCR2 in Arabidopsis guard cells evokes a transient cytoplasmic acidification that sparks Ca2+ release from the endoplasmic reticulum. A H+-induced cytosolic Ca2+ signal results in membrane depolarization through the activation of Ca2+-dependent SLAC1/SLAH3 anion channels, which enabled us to remotely control stomatal movement. Our study suggests a H+-induced Ca2+ release mechanism in plant cells and establishes HcKCR2 as a tool to dissect the molecular basis of plant intracellular pH and Ca2+ signaling.