A group from Laboratoire de Recherche en Sciences Végétales, Université de Toulouse, CNRS, UPS, Auzeville-Tolosane, France, etc. has reported on cell wall proteome (CWP) of Marchantia polymorpha.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8792609/
Plant cell walls are composite structures made of polysaccharidic polymers like pectins, hemicelluloses and cellulose as well as of lignins in lignified secondary walls. In this study, 410 CWPs of M. polymorpha were identified.
Typical examples are as follows,
Several families of CWPs involved in the remodeling of the cell wall polysaccharides networks have been identified.
Fifteen GH17 (b-1,3-glucosidases) could be involved in the hydrolysis of callose which has been found in the cell plates of all land plants.
Three GH5 (endo-b-1,4-glucanase) and five GH16 (endoxyloglucan transferases) were identified. Their substrates in cell walls are assumed to be hemicelluloses like xyloglucans or mannans and they are known to play roles in polysaccharides rearrangements during cell growth.
The identification of two GH28 (polygalacturonases), six pectin methylesterases (PMEs) and two pectin acylesterases (PAEs) is consistent with the presence of galacturonic acid in the acidic hydrolysate of M. polymorpha cell wall polysaccharides.
Finally, five GH18 (chitinases) and seven GH19 (chitinases/lyzozymes) have been identified. They have been shown to exhibit chitinase and chitinase/lysozyme activities, respectively. They have anti-fungal and anti-bacterial activities and are involved in defense reactions against biotic and abiotic stresses.
Several protein families are known to be involved in oxido-reduction reactions involving aromatic compounds in M. polymorpha cell walls. The antagonistic enzymatic activities of CIII Prxs allow them to participate in cell wall remodeling events in two opposite ways: (i) they play a role in cell wall loosening by generating reactive oxygen species able to cut non-enzymatically the cell wall polysaccharides; or (ii) they can participate in the cell walls stiffening by oxidizing aromatic compounds such as aromatic amino acids, monolignols or cinnamic acid in the presence of H2O2, or in the cross-linking of structural proteins like extensins, thus forming covalent networks.
The acquisition of a cuticle has been a major event in land plant colonization. Twenty-three GDSL lipases/acylhydrolases have been identified. A GDSL lipase/acylhydrolase has been shown to be involved in cuticle formation.
Eight proteins predicted to be D-mannose binding lectins were identified. The abundance of such proteins in the CWP could be linked to the presence of high amounts of mannans as suggested by the presence of significant amount of mannose residues in pectins- and hemicelluloses-enriched cell walls extracts.