cell wall polymers of the charophycean green alga Chara corallina: Immunobinding and biochemical screening

Immunocytochemistry, comprehensive microarray polymer profiling (CoMPP), and biochemical analysis were used to elucidate the distribution of polymers in the cell walls of seven distinct parts of the shoot region of the thallus of the charophycean green alga Chara corallina. The cell walls contain a diverse set of polymers, many of which are commonly found in the cell walls of land plants, including cellulose, pectic polymers, arabinogalactan proteins, and several polymers that are classified as cross-linking polysaccharides in embryophytes, including heteroxylans and heteromannans. Evidence of the presence of xyloglucan was also found. Cellulose and homogalacturonan were found in virtually all parts of the vegetative and reproductive shoot thallus, whereas the occurrence of other polymers in the cell walls within the different cell types was more varied. These results, which demonstrate the shared biochemical characteristics of the cell walls of Chara and of embryophytes, support previous molecular, ultrastructural, and biochemical studies demonstrating the advanced phylogenetic status of this alga in the Charophyceae. This work also suggests that several of the polymers found in the cell walls of land plants most likely evolved before the colonization of terrestrial habitats by plants.