Damien De Bellis – Electron Microscopy Facility University of Lausanne

Great collaboration with Marie Barberon and Niko Geldner! Our article on Extracellular vesiculo-tubular structures associated with suberin deposition in plant cell walls is now published in NatureComms.

Extracellular vesiculo-tubular structures associated with suberin deposition in plant cell walls

Damien De Bellis, Lothar Kalmbach, Peter Marhavy, Jean Daraspe, Niko Geldner & Marie Barberon

Nat Commun 13, 1489 (2022). https://doi.org/10.1038/s41467-022-29110-0

Suberin is a fundamental plant biopolymer, found in protective tissues, such as seed coats, exodermis and endodermis of roots. Suberin is deposited in most suberizing cells in the form of lamellae just outside of the plasma membrane, below the primary cell wall. How mono- meric suberin precursors, thought to be synthesized at the endoplasmic reticulum, are transported outside of the cell, for polymerization into suberin lamellae has remained obscure. Using electron-microscopy, we observed large numbers of extracellular vesiculo- tubular structures (EVs) to accumulate specifically in suberizing cells, in both chemically and cryo-fixed samples. EV presence correlates perfectly with root suberization and we could block suberin deposition and vesicle accumulation by affecting early, as well as late steps in the secretory pathway. Whereas many previous reports have described EVs in the context of biotic interactions, our results suggest a developmental role for extracellular vesicles in the formation of a major cell wall polymer.

First publication of the year!

Front. Plant Sci., 05 January 2022

Trafficking Processes and Secretion Pathways Underlying the Formation of Plant Cuticles

Glenn Philippe¹, Damien De Bellis^2,3, Jocelyn K. C. Rose¹ and Christiane Nawrath²^*

¹Plant Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, United States

²Department of Plant Molecular Biology, University of Lausanne, Lausanne, Switzerland

³Electron Microscopy Facility, University of Lausanne, Lausanne, Switzerland

Cuticles are specialized cell wall structures that form at the surface of terrestrial plant organs. They are largely comprised lipidic compounds and are deposited in the apoplast, external to the polysaccharide-rich primary wall, creating a barrier to diffusion of water and solutes, as well as to environmental factors. The predominant cuticle component is cutin, a polyester that is assembled as a complex matrix, within and on the surface of which aliphatic and aromatic wax molecules accumulate, further modifying its properties. To reach the point of cuticle assembly the different acyl lipid-containing components are first exported from the cell across the plasma membrane and then traffic across the polysaccharide wall. The export of cutin precursors and waxes from the cell is known to involve plasma membrane-localized ATP-binding cassette (ABC) transporters; however, other secretion mechanisms may also contribute. Indeed, extracellular vesiculo-tubular structures have recently been reported in Arabidopsis thaliana (Arabidopsis) to be associated with the deposition of suberin, a polyester that is structurally closely related to cutin. Intriguingly, similar membranous structures have been observed in leaves and petals of Arabidopsis, although in lower numbers, but no close association with cutin formation has been identified. The possibility of multiple export mechanisms for cuticular components acting in parallel will be discussed, together with proposals for how cuticle precursors may traverse the polysaccharide cell wall before their assimilation into the cuticle macromolecular architecture.