Plants have mechanisms to perceive and transmit information between its organs and tissues. These signals had long been considered as hormonal or hydraulic in nature, but recent studies have shown that electrical signals are also produced causing physiological responses. In this work we show that Venus Flytrap, Dionaea muscipula, can respond to both electrical and optical signals beside mechanical stimulations. While the Venus Flytrap does not have any neurons, it does contain transport cells with very similar characteristics to neurotransmitters and uses ionic mechanisms, as human neurons do, to generate action potentials. In our electrical stimulation study, electrodes made out of soft cloth were soaked in salt water before being placed to the midrib (+) and lobe (-). The flytrap's surface resistance was determined by subtracting out the average electrode resistance from the measured electrode to plant surface resistance, yielding an average contact resistance of around 0.98MΩ. A logarithmic amplifier was used to monitor mechanically generated electrical signals. Two electrical pulses were generated by mechanically touching the trigger hairs in the lobe twice within 20 seconds. By discharging around 600μC charge stored in a capacitor we demonstrated electrically closing of the flytrap. For optical excitation we found in our FTIR study it's tissue contains very similar protein absorption peaks to that of insects. A 7.35μm laser with ~50mw power was then used for the stimulation study. Electrical action potential was generated twice by mid-infrared photons before closure of the flytrap.

Date Published: 8 March 2013
PDF: 10 pages
Proc. SPIE 8565, Photonic Therapeutics and Diagnostics IX, 85655I (8 March 2013); doi: 10.1117/12.2005351

Published in SPIE Proceedings Vol. 8565:
Photonic Therapeutics and Diagnostics IX
Andreas Mandelis; Brian Jet-Fei Wong; Anita Mahadevan-Jansen; Henry Hirschberg M.D.; Hyun Wook Kang; Nikiforos Kollias; Melissa J. Suter; Kenton W. Gregory M.D.; Guillermo J. Tearney M.D.; Stephen Lam; Bernard Choi; Steen J. Madsen; Bodo E. Knudsen M.D.; E. Duco Jansen; Justus F. Ilgner M.D.; Haishan Zeng; Matthew Brenner; Laura Marcu, Editor(s)