Roles of cell wall peroxidases in plant development.

Class III peroxidases (CIII Prxs) are plant specific proteins. Based on in silico prediction and experimental evidence, they are mainly considered as cell wall localized proteins. Thanks to their dual hydroxylic and peroxidative cycles, they can produce ROS as well as oxidize cell wall aromatic compounds within proteins and phenolics that are either free or linked to polysaccharides. Thus, they are tightly associated to cell wall loosening and stiffening. They are members of large multigenic families, mostly due to an elevated rate of gene duplication in higher plants, resulting in a high risk of functional redundancy between them. However, proteomic and (micro)transcriptomic analyses have shown that CIII Prx expression profiles are highly specific. Based on these omic analyses, several reverse genetic studies have demonstrated the importance of the spatio-temporal regulation of their expression and ability to interact with cell wall microdomains in order to achieve specific activity in vivo. Each CIII Prx isoform could have specific functions in muro and this could explain the conservation of a high number of genes in plant genomes.