Immuno-cytolocalization of glomalin in the mycelium of the arbuscular mycorrhizal fungus Glomus intraradices

A better understanding of the role of glomalin in arbuscular mycorrhizal fungi necessitates knowledge about the cellular functions and locations of this putative heat-shock protein (Hsp). In the present study, we determined the cellular localization of glomalin in mycelium of Glomus intraradices using immuno-electron microscopy, employing the monoclonal antibody MAb32B11. We observed that there were more gold beads bound to hyphae and spore walls than in the cytoplasm. There was also differential binding within the wall layers: L3 and L2 presented more intense labeling than the L1 layer. Our data on wall-binding of glomalin are strongly suggestive of functions other than cytoplasmic (Hsp-related), and point to a possibility of mediating interactions with the biotic and abiotic soil environment.