Arabinogalactan-proteins in spore-producing land plants.

Arabinogalactan-proteins (AGPs) are proteoglycans of the extracellular matrix of plants that were first isolated and described in the 1970s. Today, the consensus is that the following features are regarded as typical for these molecules: In contrast to broad knowledge on AGPs in seed plants, insight in occurrence and structure of AGPs in spore-producing land plants (bryophytes, lycophytes and monilophytes) is very limited, although these plants are the closest living relatives to seed plants. In general, understanding of cell wall evolution is incomplete due to limited knowledge of cell wall structure of non-flowering plants.