Localization of uricase in mycorrhizas of Ophrys lutea Cav

Infected roots of Ophrys lutea present nymerous peroxisome profiles identified by diaminobenzidine (DAB) staining. The presence of uricase in these peroxisomes could also be recognized cytochemically. The activities of catalase and uricase, assayed using a crude fraction of peroxisomes, reached 0·8 μkat min^-1 protein-1 and 1·73 nakat min^-1 mg protein^-1 respectively. The role of uricase in purine metabolism is discussed in terms of host/endophyte interactions in O. lutea mycorrhzas.

MYCORRHIZAS (ORCHIDACEAE)

The host cells from endomycorrhizas of Ophrys lutea Cav. contain many coated vesicles associated with dictyosomes, with a membrane system (probably partially coated reticulum) and with the host's sequestration plasmalemma. The contents of coated vesicles stain with neither the PATAg test for polysaccharides nor with ruthenium red. The involvement of coated vesicles in the host/endophyte interactions during the establishment of O. lutea endomycorrhizas is discussed.