Bulone V. Analyses of extracellular carbohydrates in Oomycetes unveil the existence of three different cell wall types. Eukaryot Cell. 2013; 12: 194–203. doi

Some of the most devastating plant and animal pathogens belong to the oomycete class. The cell walls of these microorganisms represent an excellent target for disease control, but their carbohydrate composition is elusive. We have undertaken a detailed cell wall analysis in 10 species from 2major oomycete orders, the Peronosporales and the Saprolegniales, thereby unveiling the existence of 3 clearly different cell wall types: type I is devoid ofN-acetylglucosamine (GlcNAc) but contains glucuronic acid and mannose; type II contains up to 5%GlcNAc and residues indicative of cross-links between cellulose and 1,3--glucans; type III is characterized by the highest GlcNAc content (>5%) and the occurrence of unusual carbohydrates that consist of 1,6-linked GlcNAc residues. These 3 cell wall types are also distinguishable by their cellulose content and the fine structure of their 1,3--glucans. We propose a cell wall paradigm for oomycetes that can serve as a basis for the establishment of cell wall architectural models and the further identification of cell wall subtypes. This paradigm is complementary to morphological andmolecular criteria for taxonomic grouping and provides useful information for unraveling poorly understood cell wall carbohydrate biosynthetic pathways through the identification and characterization of the corresponding enzymes. The oomycete class comprises a large number of eukaryotic sap-robes and parasites that are widely distributed worldwide. Some of these microbial species have important environmental and economic impacts as pathogens of plants or animals, in both natural habitats and industrial cultures. Typical examples are th