Plant cell walls are composite structures surrounding cells and involved in both mechanical
support and perception of their environment. They are mainly composed of polysaccharides (90-95% of
their mass) and proteins (5-10%). The cell wall proteins (CWPs) contribute to the arrangements and
modifications of polymer networks and to cell-to-cell communication. The structure and composition of
cell walls are not uniform in the whole plants, but rather specialized in different cell types to fulfil different
functions. As examples, two kinds of cells are covered with extracellular structures composed of
lipids: epidermal cells of aerial organs synthesize a cuticle on their outside surface whereas endodermal
root cells form a suberin surrounding strip. In both cases, these particular hydrophobic layers contribute
to the protection of the cells against attacks by pathogens or abiotic stresses and regulate physiological
processes. If the intracellular biosynthesis of the molecules forming these layers starts to be welldescribed,
the mechanisms of their assembly beyond the plasma membrane remain largely unknown. In
this review, this issue is addressed on the basis on cell wall proteomics data which has allowed the identification
of many CWPs possibly related to lipid metabolism during the last years, in particular in
Arabidopsis thaliana and tomato. These data are combined with transcriptomics and genetics studies.
The main known roles of extracellular proteins related to lipid metabolism are discussed.
Keywords: Arabidopsis thaliana, cell wall, cuticle, plant, proteomics, suberin, tomato.
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