Mechanical Effects of Cellulose, Xyloglucan, and Pectins on Stomatal Guard Cells of Arabidopsis thaliana
Hojae Yi, Yue Rui, Baris Kandemir, James Z. Wang,
Charles T. Anderson, and Virendra M. Puri
The Pennsylvania State University
Abstract:
Stomata function as osmotically tunable pores that facilitate gas
exchange at the surface of plants. Stomatal opening and closure are
regulated by turgor changes in guard cells that result in mechanically
regulated deformations of guard cell walls. However, how the
molecular, architectural, and mechanical heterogeneities that exist in
guard cell walls affect stomatal dynamics is unclear. In this work,
stomata of wild type Arabidopsis thaliana plants or of mutants lacking
normal cellulose, hemicellulose, or pectins were experimentally
induced to close or open. Three-dimensional images of these stomatal
complexes were collected using confocal microscopy, images were
landmarked, and three-dimensional finite element models (FEMs) were
constructed for each complex. Stomatal opening was simulated with a 5
MPa turgor increase. By comparing experimentally measured and
computationally modeled changes in stomatal geometry across genotypes,
anisotropic mechanical properties of guard cell walls were determined
and mapped to cell wall components. Deficiencies in cellulose or
hemicellulose were both predicted to stiffen guard cell walls, but
differentially affected stomatal pore area and the degree of stomatal
opening. Additionally, reducing pectin molecular mass altered the
anisotropy of calculated shear moduli in guard cell walls and enhanced
stomatal opening. Based on the unique architecture of guard cell walls
and our modeled changes in their mechanical properties in cell wall
mutants, we discuss how each polysaccharide class contributes to wall
architecture and mechanics in guard cells. This study provides new
insights into how the walls of guard cells are constructed to meet the
mechanical requirements of stomatal dynamics.
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Citation:
Hojae Yi, Yue Rui, Baris Kandemir, James Z. Wang, Charles T. Anderson
and Virendra M. Puri, ``Mechanical Effects of Cellulose, Xyloglucan,
and Pectins on Stomatal Guard Cells of Arabidopsis thaliana,''
Frontiers in Plant Science, vol. 9, article 1566, pp. 1-18, 2018.
© 2018 Yi, Rui, Kandemir, Wang, Anderson, and Puri.
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Last Modified:
November 5, 2018
© 2018