Viruses associated with white bryony (Bryonia cretica L.) mosaic in Northern Italy

Plants of white bryony (Bryonia cretica L. formerly known as B. dioica Jacq.) in Northern Italy, bearing mottle and mosaic leaf symptoms, contained viruses producing severe disease when sap-inoculated to cucumber, zucchini squash, marrow and watermelon. Negative staining and electron microscopy showed that flexuous particles were present, identified as those of potyviruses from their length and fine structure, and by the presence of pinwheel-related structures. Thin sectioning confirmed the presence of pinwheels in infected tissues. No other virus particle type was observed. Immunoelectron microscopy (decoration) gave evidence for the presence of three potyviruses, P I, P II and P III. An antiserum against white bryony mosaic virus (a carlavirus) reacted strongly with P I, indicating that the original antigen suspension injected to prepare the serum must have contained P I (or a closely related virus) as well as the carlavirus. P I did not react with any other potyvirus antiserum tested. P II was serologically related to both celery mosaic and bean yellow mosaic viruses, and P III was closely related to celery mosaic virus but not bean yellow mosaic virus. Spiral structures were often observed wrapped around the potyvirus particles. It is concluded that white bryony, a common perennial plant, probably acts as a reservoir of agriculturally important viruses. Piante di Bryonia cretica L. (= B. dioica Jacq.) con sintomi di maculatura e mosaico fogliare sono state rinvenute nell'Italia settentrionale. Esse contenevano virus trasmissibili per sueco che hanno indotto sintomi gravi su Cetriolo, Zucchino e Anguria inoculate meccanicamente. L'osservazione al microscopio elettronico di estratti grezzi colorati negativamente, ha messo in evidenza particelle virali allungate e flessuose che, in base alia loro lunghezza e morfologia e per la presenza di strutture correlate a inclusioni a girandola, sono state identificate come potyvirus. Nessun altro tipo di particelle virali è stato messo in evidenza e la presenza di inclusioni a girandolae-stata confermata dall'osservazione al microscopio elettronico di sezioni ultrasottili. Esperimenti di immunomicroscopia elettronica (técnica della decorazione) hanno dimostrato la presenza di tre différend potyvirus, P I, P II e P III. Un antisiero specifico del mosaico della Brionia (un carlavirus) ha reagito fortemente con P I. È perianto evidente che la preparazione di antigene usata per ottenere tale antisiero doveva conteneré,