Minisymposium 17: Water

Abs # 32003: Volume and Surface Area Changes are Coordinated with Plasam Membrane Mobilization in Guard Cells

Presenter:	Shope, Joseph C, jshope@biology.usu.edu
Authors	Shope, Joseph C (A)   Mott, Keith A (A)
Affiliations:	(A): Biology Department, Utah State University

Guard cells undergo large changes in volume and surface area as stomata open and close. The integrity of the plasma membrane must be maintained during these changes in surface area, and we have shown previously that plasma membrane is internalized as guard-cell surface area decreases. To further investigate how plasma membrane integrity is maintained as surface area and volume change, we treated isolated epidermal peels of Vicia faba with pharmacological agents known to affect various aspects of membrane trafficking. We then examined the response of the guard cells to osmotic treatments. In control cells, these treatments produced reversible membrane internalization and reversible changes in volume and surface area. Confocal microscopy revealed that some of the pharmacological agents inhibited membrane internalization following a hyper-osmotic treatment. Measurement of guard cell dimensions revealed that these agents also substantially reduced the rate at which guard cell volume changed in response to the hyperosmotic treatment. Other agents had no effect on guard cell shrinking and membrane internalization in response to a hyper-osmotic treatment, but prevented re-swelling in response to hypo-osmotic treatments. We hypothesize that the hydraulic conductivity of the plasma membrane is controlled to coordinate volume and surface area changes with membrane mobilization.