Arabinogalactan proteins are expressed at the symbiotic interface in root nodules of Alnus spp.

•  We have characterized the origin and distribution of arabinogalactan proteins (AGPs) at the symbiotic interface of dinitrogen (N )-fixing root nodules of Alnus spp. The interface between the host plant cell and the microsymbiont is an important zone for signaling and growth regulation during nodulation. Arabinogalactan proteins are glycoproteins that have adhesive properties, and, potentially, participate in cell wall assembly, direction of growth, and signaling cascades.