Detection of Cerato-Ulmin on Aggressive Isolates ofOphiostoma ulmiby Immunocytochemistry and Scanning Electron Microscopy

Abstract

The surface deposition and accumulation of cerato-ulmin by the aggressive isolates of Ophiostoma ulmi were demonstrated using polyclonal antiserum directed against cerato-ulmin, 100-150-nm protein A-gold particles, and a scanning electron microscope. The protein A-gold complex was present on the fungal surface in areas containing the toxin cerato-ulmin (CU). The gold label was present on the surface of the vegetative hyphase, synnemata, synnematal spores, perithecia, and ostiolar hairs of the aggressive isolates of O. ulmi. The protein A-gold label was either evenly distributed on the fungal surface or in the form of large surface aggregates. The nonaggressive isolate Q412 of O. ulmi had a low concentration of protein A-gold label on its fungal structures. When the specific CU antiserum was replaced by preimmune serum, a lack of the protein A-gold label was evident on all fungal structures of the aggressive isolate VA of O. ulmi.