BIC Seminar: Prof. Rainer Hedrich

Probing plant signalling via Channelrhodopsin optogenetics

Date: 28 April 2026

Time: 14:50

Location: C0333, Orion, Wageningen Campus

Abstract:

Membrane electrical excitation, often associated with the transient rise in cytosolic Ca²⁺ and H⁺ concentration, represent universal signalling elements that couple a wide range of stimuli to their characteristic responses, including in plants. Despite decades of intensive research, many of the signal transduction elements involved in Ca²⁺ and pH signalling are yet to be elucidated. Progress has been hampered due to our inability to trigger defined changes in cytosolic Ca²⁺ concentration, without provoking changes in plasma membrane electrical properties. Over the past 5 years, new game-changing ion channel optogenetic tools have been introduced into plants to answer long-standing questions in plant biology.

In this presentation I will describe how we have engineered the light-gated ChannelRhodopsins CHRs selective for anions (ACR1), H⁺ (KCR2) or Ca²⁺ (XXM2.0) and to obtain stable expression in Arabidopsis and tobacco plants. These tools provide us with the unique opportunity to non-invasively induce voltage, Ca²⁺ and H⁺ signals in guard cells as well as any plant cell/tissue/organ type of interest. Furthermore, I will describe how CHRs provide a valuable tool to non-invasively excite the plasma membrane, trigger H⁺ or Ca²⁺ influx, and provoke H⁺ or Ca²⁺ induced Ca²⁺ release. This allows to study the interrelation between plant pH and Ca²⁺ signalling on one side, and electrical excitation on the other. Depending on the CHR and stimulation features (pulse number, length, and frequency) one can remote control single cell action, long-distance transport as well as growth and shape or plant organs. Our findings challenge established paradigms relating to the way proton, calcium, and voltage signalling are interconnected in plants and rethink of mechanisms involved.