Cytochemical and immunocytochemical investigation of the mycoparasitic interaction between Stachybotrys elegans and its host Rhizoctonia solani (AG-3)

Hyphal interaction between the mycoparasite Stachybotrys elegans and its host Rhizochonia solani was investigated cytochemically for the detection of sugar residues using lectin-gold complexes, and immunocytochemically with an antibody raised against purified fimbriae. N-acetyl-D-glucosamine oligomers were revealed in the cell walls of both fungi. The absence of these sugar oligomers at the penetration sites of the host cell wall suggests that extracellular chitinases produced by S. elegans may be involved in the mycoparasitic process. D-galactose residues were also detected throughout the cell wall of S. elegans and may have a role in the recognition process. in R. solani cells, labelling studies revealed that papillae produced in response to attack by the mycoparasite contained N-acetyl-D-glucosamine and to a lesser extent either mannosyl or glucosyl sugar residues. Fimbrial proteins were localized within the extracellular matrix that surrounds S. elegans cells when they were confronted with its host. The present study provides evidence that surface molecules are implicated in the interaction between S. elegans and its host.