Bending and Squeezing: Gradual Electric Potentials Encode Mechanical Stimuli in Poplar.

Area of Science:

• Plant electrophysiology
• Biophysics
• Mechanobiology

Background:

• Mechanical stimuli like wind trigger rapid electrical signals in plants.
• The precise mechanisms behind these plant responses are not fully understood.
• Investigating these signals is crucial for understanding plant sensory biology.

Purpose of the Study:

• To investigate the electrophysiological responses of young poplar trees to controlled stem bending.
• To characterize the nature of the electrical signals generated by mechanical stimuli.
• To elucidate the biophysical mechanisms underlying mechanically induced electrical signaling in trees.

Main Methods:

• Controlled stem bending experiments on young poplar trees.
• Electrophysiological recordings to measure electrical potentials.
• Analysis of signal propagation, attenuation, and waveform characteristics under varying stimulus conditions.

Main Results:

• A novel gradual potential (GP) was identified, differing from action potentials.
• GP amplitude at the site of stimulation was invariant to stimulus speed and intensity.
• GP propagation distance and attenuation were dependent on stimulus speed and intensity, with faster/stronger stimuli traveling further.
• GP responses to stem bending were similar to those from root pressurization, suggesting hydraulic-electrical coupling.
• Key GP features indicated a nonlinear transduction process beyond simple hydraulic diffusion.

Conclusions:

• Mechanically induced electrical signals in trees involve a gradual potential (GP) with unique properties.
• The findings suggest a complex interplay between hydraulic perturbations and nonlinear electrical signal transduction.
• This study provides a framework for understanding the biophysical basis and physiological relevance of electrical signaling in trees.