Penium margaritaceum, a charophycean green alga as a novel model organism for plant cell wall studies

D. DOMOZYCH, I. SØRENSEN, W. G. T. WILLATS, J. M. ESTEVEZ, J. K. C. ROSE & P. ULVSKOV.

Porto, Portugal

Congreso; XII Cell Wall Meeting; 2010

European cell wall network

The plant cell wall is a structurally complex and dynamic extracellular covering whose evolution was of paramount significance to green plant evolution and whose applications to human economy have been profound. The elucidation of the structure, function and biosynthesis of the polymeric constituents of the wall represents a central goal of the biological sciences and modern research has greatly benefited from the identification and use of model organisms derived from the major groups of land plants. The Charophycean Green Algae or CGA, i.e., the group of extant green algae most closely related to land plants, possess many of the cell wall polymers and wall-based developmental mechanisms that are found in land plants. Yet, until recently, no model organism was found in this taxon. In recent comprehensive analyses of the cell walls of the CGA from multiple laboratories, a putative unicellular model organism has been identified that may be well-suited for deciphering the foundations of the cell wall dynamics in both this primitive ancestral group and green plants in general. Penium margaritaceum is a fast-growing desmid (Zygnematales) that may be grown in large synchronous cultures and manipulated with relative ease in a variety of live cell experiments. Penium produces only a simple primary cell wall that includes cellulose, homogalacturonan (HG)-rich pectin, and hydroxyproline rich glycoproteins (HRGPs) including arabinogalactan proteins (AGPs) and extensins. The processing of HG during cell development can be carefully monitored in live cells using monoclonal antibody labeling. HG secretion and de-esterification occurs in a distinct bipolar displacement mechanism originating at the central isthmus region of the cell. Cell wall processing may be selectively altered by application of specific cytoskeletal drugs, secretory and cellulose synthesis inhibitors that results in the production of new morphotypes including novel multicellular forms. AGPs are located throughout the cell wall matrix and are involved in adhesion mechanisms. Recently, significant genome and transcriptome data is becoming available.