Electric Plants
Animals, like you and I, possess nervous systems that allow the different parts of the body to communicate with each other. Nerve cells branching throughout the body pass along electric signals that help your brain interpret different sensory inputs and coordinate the appropriate responses, such as quickly pulling your hand away from a hot stove.
Plants clearly lack the same capabilities as animals, which is a good thing. Otherwise, all my vegetables might hop off the stove in the very act of making stir fry, but I digress. Although plants lack animal nerve cells and musculature, they are still capable of communicating through electric signals, commonly known as the “green circuit.”
When a part of a plant experience stress, such as mechanical wounding, a drop in temperature or high levels of salt, in can generate an electrical signal that travels along the vasculature of the plant to different leaves and tissues. In distant parts of the plant, this signal can change gene expression, alter the rate of photosynthesis or induce the production of hormones involved in the defense against pathogens and insects. Most dramatically, some plants use electrical signals to trigger changes in the positions of leaves to catch a tasty morsel, as is the case for the Venus flytrap (Dionaea muscipula), or to protect leaves from damage, which is true of the sensitive plant (Mimosa pudica).
Electric signals produced by plants are fast, relatively speaking, traveling to distant leaves over the span of several seconds or 1-2 minutes. Researchers can measure the signal as it travels through the plant using extremely fine glass electrodes. A research group from the University of Wisconsin-Madison can even visualize the spread of the electric signal in real-time using a line of plants that express a fluorescent sensor of calcium ions. As the electric signal travels throughout the plant, changes in the levels of calcium ions cause the vasculature to fluoresce a vibrant green.
MIT has even taken advantage of these electric signals to create plant-robot hybrids. Electrodes inserted into a plant can detect signals produced in response to different stimuli. These signals are augmented and used to trigger the movement of robotic parts. For example, one cyborg plant was given the capability of wheeling itself toward a light source.
Such advances do not bode well for the future of stir-fry.
Brian Rutter, PhD, is the cofounder of Thing in a Pot Productions and a postdoctoral researcher in plant biology at Indiana University. Subscribe to our newsletter to receive our “Things About Things – Odd Facts About Plants” and video production tips in your inbox every month!
Works Cited:
García-Servín, M. Á., Mendoza-Sánchez, M., & Contreras-Medina, L. M. (2021). Electrical signals as an option of communication with plants: a review. Theoretical and Experimental Plant Physiology, 1-15.
McDermott, A. (2019). Science and Culture: Light-seeking mobile houseplants raise big questions about the future of technology. Proceedings of the National Academy of Sciences, 116(31), 15313-15315.
Toyota, M., Spencer, D., Sawai-Toyota, S., Jiaqi, W., Zhang, T., Koo, A. J., ... & Gilroy, S. (2018). Glutamate triggers long-distance, calcium-based plant defense signaling. Science, 361(6407), 1112-1115.