The occurrence of cell wall-associated arabinogalactan proteins in the Hepaticae

Arabinogalactan proteins (AGPs) constitute a class of hydroxyproline-containing glycoproteins. Accumulated evidence that hydroxyproline-containing protein(s) (hyp-protein) functions in the correlative control of leaf and branch development in liverworts prompted our investigation of the occurrence of AGPs in hepatics. Their presence can be detected in tissues as well as tissue extracts by means of Yariv ß-glucosyl reagent, an artificial antigen which specifically binds, precipitates, and stains AGPs red-orange. We used this reagent to detect AGPs associated with the cell walls of eight species of hepatics, Haplomitrium mnioides (Lindb.) Schust., Scapania nemorosa (L.) Dum., Nowellia curvifolia (Dicks.) Mitt., Jungermannia leiantha Grolle, Gymnocolea inflata (Huds.) Dum., Fossombronia foveolata Lindb., Riccardia sinuata (Dicks.) Trevis, and Riccia duplex Lorbeer. Since these species represent both subclasses, as well as four of seven orders, of the Hepaticae, these results suggest that AGPs may be regularly occurring components of liverwort cell walls. Whether AGPs function in morphoregulation remains to be determined.