Optogenetics-based investigation of wounding-induced calcium and electrical signaling between lateral roots.

• Applicant: Dr. Angel Baudon
• Subject Area: Plant Physiology ; Plant Biochemistry and Biophysics
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 564693890

Plants had to develop defense mechanisms that travel throughout the organism over long distances to face external aggression, such as phytophagous insect attacks. Leaf-to-leaf and root-to-leaf propagation of electrical and Ca2+ waves have been observed following wounding but root-to-root communication has never been tested. In this proposal, I will combine new optogenetic approaches and cutting-edge localized light stimulations to understand how Ca2+ and electrical signals propagate in the network to favor plant defense mechanisms in roots distant from the wounding site, allowing it to anticipate phytophagous insect attack. I will first record electrical and Ca2+ signals locally in Arabidopsis thaliana seedling roots to show that roots respond to injury by electrical-Ca2+ signaling. Then, I will investigate whether this wounding signal can propagate to neighboring roots within the same plant. Given the ability of glutamate to act as a damage-associated molecular pattern following a wound in the shoot, I will test the ability of this amino acid to trigger local and long-distance electrical and Ca2+ signaling. Once this root-to-root wounding communication is demonstrated, I will mimic these signals using optogenetic tools to control the membrane potential and Ca2+ levels in roots non-invasively. Using a mosaic microscope, I will record the roots' electrical and Ca2+ activity while performing localized optogenetic stimulations at different locations in the roots. This approach will allow me to establish an "electrical connection map" of the root network depicting preferential directions of electrical signals within the root architecture. Finally, I will investigate the molecular mechanisms responsible for the propagation of electrical signals from a root to ist neighbors using pharmacological and mutant approaches. I will focus on the role of glutamate-like receptors since their involvement is crucial in the propagation of wound signaling from leaf to leaf. Moreover, I will investigate the involvement of a potential Ca2+-induced Ca2+ release mechanism in the propagation of wounding signal from root to root. Understanding how lateral roots communicate with each other and by which mechanisms would allow the development of compounds that boost plant immune reactions, making them more resistant to pathogens instead of using insecticides that kill all neighboring insects.

• DFG Programme: WBP Position