New publication from Damien De Bellis

Kian Hématy, Damien De Bellis, Xin Wang, Ari Pekka Mähönen, Niko Geldner. 

Analysis of exocyst function in endodermis reveals its widespread contribution and specificity of action. 

Plant Physiology, 2022;, kiac019,

The exocyst is the main plasma membrane vesicle-tethering complex in eukaryotes and is composed of eight different subunits. Yet, in plant genomes, many subunits display multiple copies, thought to reflect evolution of complex subtypes with
divergent functions. In Arabidopsis thaliana root endodermal cells, the isoform EXO70A1 is required for positioning of
CASP1 at the Casparian Strip Domain, but not for its non-targeted secretion to the plasma membrane. Here, we show that
exo84b resembles exo70a1 mutants regarding CASP1 mistargeting and secretion of apoplastic proteins, but exo84b additionally affects secretion of other integral plasma membrane proteins. Moreover, conditional, cell-type-specific gene editing of
the single-copy core component SEC6 allows visualization of secretion defects in plant cells with a complete lack of exocyst
complex function. Our approach opens avenues for deciphering the complexity/diversity of exocyst functions in plant cells
and enables analysis of central trafficking components with lethal phenotypes.

First publication of the year!

First publication of the year!

Front. Plant Sci., 05 January 2022

Trafficking Processes and Secretion Pathways Underlying the Formation of Plant Cuticles

Glenn Philippe1Damien De Bellis2,3Jocelyn 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.

cryo-lamellae at EMF … We are getting closer !

After having received efficient and didactic trainings from TFS and Leica, we are practising the cryo-CLEM workflow! Olivia, Damien and Jean are working hard on each step but the workflow is smooth so far.. Thanks to all the suppliers, UNIL logisitics, TFS and Leica service engineers and trainers ! it is magic to observe the fluorescence signal on a frozen grid…

Welcome Wei Jiao

We have the pleasure to welcome Wei Jiao PhD as post-doc. She is developing complicated CLEM workflows in order to assess what type of services the EMF will be able to offer in the future. Concentrating on neuroscience project, she will evaluate and make proofs-of-concept for new approaches before teaching them to the team. She will also provide these approaches as service once they have been fully proofed and are routine, meaning cost-efficient for our users.