Straining the root on and off triggers local calcium signalling

Area of Science:

• Plant biology
• Mechanobiology
• Cellular signaling

Background:

• Plant roots perceive mechanical cues from their environment, essential for growth and adaptation.
• Understanding root responses to mechanical stress is limited, especially compared to aerial plant parts.
• Roots encounter mechanical stimuli like soil obstacles and settlement, necessitating cellular response mechanisms.

Purpose of the Study:

• To investigate cellular responses of plant roots to mechanical compression.
• To analyze root cell deformation and calcium signaling under controlled mechanical stimulation.
• To elucidate the properties of root mechanosensing and calcium elevation.

Main Methods:

• Developed a microfluidic system with a microvalve for controlled mechanical stimulation of plant roots.
• Utilized plants expressing the R-GECO1-mTurquoise calcium reporter to visualize calcium dynamics.
• Applied lateral pressure to roots to induce deformation and measure calcium responses.

Main Results:

• Lateral pressure caused elastic deformation in root cortical cells.
• Mechanical stimulation elicited a multi-component calcium signal upon pressure onset and release.
• Calcium response intensity correlated with applied pressure but showed habituation to successive stimuli.
• Calcium elevation was spatially restricted to the stimulated tissue and did not propagate.

Conclusions:

• Root cell straining, not just stressing, is key for triggering calcium signals.
• Strain sensing, spatial restriction, and habituation are fundamental properties of root mechanical signaling.
• These findings contribute to understanding how roots adapt to mechanical cues in the soil.