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Cell to Cell adhesion and Communication
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Keywords : Arabidopsis thaliana - FT-IR microspectrocopy -pectin - herbicides - cell elongation

Doctoral school affiliation : ED 145 (Sciences du végétal) Université Paris-Saclay

Contacts :

Institut Jean-Pierre Bourgin, UMR1318 INRA-AgroParisTech
Bâtiment 1
INRA Centre de Versailles-Grignon
Route de St-Cyr (RD10)
78026 Versailles Cedex France

tél : +33 (0)1 30 83 30 00 - fax : +33 (0)1 30 83 33 19

Group Leader
Grégory Mouille

Senior Scientist

 

Salem Chabout
Technician

Summary :

 

 

 

Plant cells are surrounded by a ligno-cellulosic cell wall, which is at the same time sufficiently strong to withstand the stresses exerted by the high turgor pressure of the protoplast and sufficiently plastic for cell expansion to occur. The cell wall of growing cells (primary wall) consists primarily of a complex network of polysaccharides. It plays a key role in growth, development and the interaction with the abiotic and biotic environment of the plant. Despite their importance, the mechanisms of the synthesis, transport, assembly (Mouille et al., 2007, Geshi et al, 2013, Poulsen 2014) and maturation of these wall polymers remain poorly understood (Paque et al, 2014, Séchet et al., 2016). Furthermore the link between cell wall modifications, its mechanical properties and in particular the cell adhesion. To understand better these processes at the level of a growing organ, we combine molecular genetics, biochemistry and cytology on the model plants Arabidopsis thaliana and Brachypodium distachyon and crops such as Rice.


Figure 1 : Immunolocalisation of Xyloglucanes of Arabidopsis plantlets. In magenta: calcofluor stained cellullose, in cyan: an antibody LM15 label ; compositeimage of dying and immunolabelling. scale 50µm. Asymetric distribution of xyloglucanes in some cells.


   

Main Results :
Cell to cell adhesion in plants is mediated by the cell wall in which the components are crosslinked in order to create a continuum of polysaccharides linking the cells together. However the cell wall is a dynamic compartment that participates in growth and development through its constant loosening and remodelling and it is not very clear how cell adhesion is actually maintained in these conditions. In order to get a better understanding of the mechanisms that control cell adhesion in plants we used a combination of a forward genetic suppressor screen and a chemical genomic suppressor screen on the cell adhesion defective and pectin synthesis deficient mutants, and have isolated a number of suppressor mutants and molecules implicated in cell adhesion.
We also explore, whith collaborators (Amiens, Vienna, Heildeberg) the control of de-methyesterification of pectins. Indeed pectins are acidic polysaccharides, made of galacturonic acid, synthesized in the Golgi in a highly methylesterified form. In the cell wall, enzymatic de-methylesterification controls the spatial and temporal variation in physicochemical properties of the cell wall. This controls numerous biological processes such as cellulose deposition, secondary cell wall assembly, growth and cell adhesion (Mouille et al., 2007), meristem formation (Peaucelle et al., 2008), fertilization, fruit maturation, responses to pathogens and abiotic stresses, etc. In this context our objectives are: i) Understanding the control of de-methylesterification. What is the role of the large families of pectin methylesterases (PME) and PME inhibitors(PMEI) (Wolf et al., 2009; Pelletier et al., 2010; Guenin et al., 2011, Sénéchal 2014); ii) Understanding the impact of de-methylesterification on pectin metabolism and the mechanical properties of the wall (Peaucelle et al., 2011 and iii) dissecting the role of pectin-mediated feedback signaling (Wolf et al., 2012)


.Figure 2 : Arabidopsis mutants with defective cellular adhesion.confocal projected images of Arabidopsis plantlets stains with propidium iodide. Scale 75µm.In Cellular adhesion defective in mutants are observed compared to the control (left)
 


   

Selected Publications :


Geshi N., Johansen J.N., Dilokpimol A., Rolland A., Belcram K., Verger S., Kotake T., Tsumuraya Y., Kaneko S., Tryfona T., Dupree P., Scheller H.V., Hofte H., and Mouille G. 2013. A galactosyltransferase acting on arabinogalactan protein glycans is essential for embryo development in Arabidopsis. The Plant journal doi: 10.1111/tpj.12281

Wolf, S., Mravec, J., Greiner, S., Mouille, G., and Hofte, H. (2012). Plant Cell Wall Homeostasis is Mediated by Brassinosteroid Feed-back Signalling. Current Biology 18, 1732-7.

Bischoff V, Desprez T, Mouille G, Vernhettes S, Gonneau M, Hofte H. 2011. Phytochrome regulation of cellulose synthesis in Arabidopsis. Current Biology, 21 : 1821-1827.

Pelletier S, Van Orden J, Wolf S, Vissenberg K, Delacourt J, Assoumou Ndong Y, Pelloux J, Bischoff V, Urbain A, Mouille G, Lemonnier G, Renou JP, Hofte H. (2010) A role for pectin de-methylesterification in a developmentally-regulated growth acceleration in dark-grown arabidopsis hypocotyls. New Phytologist 188, 726-39

The International Brachypodium Initiative, (Including Mouille, G., Hematy, K., Hofte, H.) (2010). "Genome sequencing and analysis of the model grass Brachypodium distachyon." Nature 463: 763-768.

Peaucelle, A., Louvet, R., Johansen, J.N., Hofte, H., Laufs, P., Pelloux, J. and Mouille, G. (2008) Arabidopsis phyllotaxis is controlled by the methyl-esterification status of cell-wall pectins. Current Biology, 18, 1943-1948.

 

 


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