Probing plant signal processing optogenetically by two channelrhodopsins

To study the basis for encoding of specificity in plant signal processing, we employed light-gated ion channels (channelrhodopsins). We developed a genetically engineered channelrhodopsin variant called XXM 2.0 with high Ca2+-conductance that enabled triggering cytosolic Ca2+ elevations in planta. The transcriptional response of light-induced Ca2+ influx via XXM 2.0 was studied in Nicotiana tabacum leaf cells side-by-side with the light-gated anion channelrhodopsin ACR1 2.0.