Doctor of Philosophy, Pennsylvania State University (2018)
Jose Dinneny, Postdoctoral Faculty Sponsor
Synergistic Pectin Degradation and Guard Cell Pressurization Underlie Stomatal Pore Formation.
Stomatal pores are vital for the diffusion of gasses into and out of land plants and are, therefore, gatekeepers for photosynthesis and transpiration. Although much published literature has described the intercellular signaling and transcriptional regulators involved in early stomatal development, little is known about the cellular details of the local separation between sister guard cells that give rise to the stomatal pore, or how formation of this pore is achieved. Using 3D time-lapse imaging, we found that stomatal pore formation in Arabidopsis thaliana is a highly dynamic process involving pore initiation and enlargement, and traverses a set of morphological milestones in 3D. Confocal imaging data revealed an enrichment of exocytic machinery, de-methyl-esterified pectic homogalacturonan (HG), and an HG-degrading enzyme at future pore sites, suggesting that both localized HG deposition and degradation might function in pore formation. By manipulating HG modification via enzymatic, chemical, and genetic perturbations in seedling cotyledons, we found that augmenting HG modification promotes pore formation, whereas preventing HG de-methyl-esterification delays pore initiation and inhibits pore enlargement. Through mechanical modeling and experimentation, we tested whether pore formation is an outcome of sister guard cells being pulled away from each other upon turgor increase. Osmotic treatment to reduce turgor pressure did not prevent pore initiation, but did lessen pore enlargement. Together, these data provide evidence that HG delivery and modification, and guard cell pressurization, make functional contributions to stomatal pore initiation and enlargement.
View details for DOI 10.1104/pp.19.00135
View details for PubMedID 30804009
- Mechanical Effects of Cellulose, Xyloglucan, and Pectins on Stomatal Guard Cells of Arabidopsis thaliana FRONTIERS IN PLANT SCIENCE 2018; 9
- Balancing Strength and Flexibility: How the Synthesis, Organization, and Modification of Guard Cell Walls Govern Stomatal Development and Dynamics FRONTIERS IN PLANT SCIENCE 2018; 9