How does plasmalemma surface area accommodate alterations in guard cell volume during stomatal closing?

During stomatal movement, guard cells undergo considerable and repetitive variations in cell volume and consequently surface area over a period of minutes. Due to limited stretching capability of the plasmalemma, alterations in the surface area must accommodate the volume changes through membrane turnover. Using fluorescence imaging and electrophysiology techniques, extensive studies imply that endocytosis may be a critical mechanism for the plasmalemma turnover. In contrast to the conventional studies, using transmission electronic microscope in combination with laser confocal microscope so that the membrane turnover can be detected without a resolution limitation, our works, recently published in Journal of Experimental Botany, has provided strong evidences that excretion and folding of plasmalemma are critical for the accommodation of the cell volume alterations in intact guard cells in Vicia faba L. These results have opened a new perspective on the mechanism for the membrane turnover during stomatal movement. In this addendum, we further discuss some key issues about the mechanisms for the accommodation of the cell volume alterations during stomatal movements.