The plant cytoskeleton controls regulatory volume increase

Area of Science:

• Plant Cell Biology
• Biophysics
• Molecular Plant Physiology

Background:

• Cell volume regulation is crucial for plant adaptation to osmotic stress.
• Plant protoplasts swell rapidly under hypoosmotic shock, indicating release of membrane material from internal stores.
• Membrane stability relies on the submembraneous actin cytoskeleton, prompting investigation into its role in volume control.

Purpose of the Study:

• To investigate the role of the cytoskeleton in plant protoplast volume regulation under osmotic stress.
• To determine if cytoskeletal organization influences osmotic tolerance in grapevine cell lines.
• To elucidate the mechanisms by which the cytoskeleton controls membrane dynamics during cell volume changes.

Main Methods:

• Utilized two grapevine cell lines with differing osmotic tolerance.
• Quantified regulatory volume control using hydraulic conductivity (Lp) measurements.
• Manipulated the cytoskeleton using chemical reagents, bacterial elicitor Harpin, phospholipase D activation, and optochemical engineering of actin.

Main Results:

• Demonstrated a significant role for the cytoskeleton in protoplast swelling during osmotic stress.
• Observed differential cytoskeletal responses in cell lines with varying osmotic tolerance.
• Found that cytoskeletal manipulation, but not calcium or membrane fluidity changes, effectively altered Lp.
• Optochemical engineering of actin induced localized cell deformation, indicating increased Lp.

Conclusions:

• The submembraneous cytoskeleton is a key regulator of plant cell volume control.
• Cytoskeletal dynamics dictate the release of intracellular membrane stores during osmotic adaptation.
• Findings provide a model for cytoskeleton-mediated membrane trafficking in response to osmotic challenges.