Presenza di un «Potyvirus» sul Carciofo (Cynara scolymusL.) in Sardegna

A latent virus of artichoke has been isolated in Sardinia (Italy). The virus causes characteristic local lesions onGomphrena globosaL. andChenopodium amaranticolorCoste et Reyn., and systemic symptoms onNicotiana benthamianaDomin. andN. clevelandiiGray. In artichoke crude sap the virus has a longevity in vitro of 20-30 hours, a dilution-end point between 10-3and 10-4and a thermal inactivation point between 55 and 60°C. The purification of the virus has been obtained from artichoke with two cicles of differential centrifugation followed by sucrose density gradient centrifugation. The purified suspensions had an ultraviolet light (UV) ab sorption spectrum typical of the nucleoproteins with Emax= 260-262 nm; Emin= 246 nm; and a ratio E280/E260of 0,85 which suggests a RNA content of the virus of about 5,5%. Electron microscope observation showed that negative stained partially purified virus suspensions are composed of filamentous parti cles with a normal lenght (NL) of 730 nm and a mode of the lenght distributions of 729 nm; moreover, ultrathin sections of tissue fragments from leaves of mechanically inocu1atedNicotiana benthamianacontained cytoplasmic inclusions of the pinwheel type. In serological tube tests, partially purified virus suspensions reacted with homologous serum (titre 1 : 1024) and a serum immune to an ALV (Artichoke Latent Virus) from Bari. These results have been substantially confirmed by serological tests with the method of «antibody coating of virus parti cles » by immune electron microscopy. I t is obvious that a latent potyvirus is widespread in artichoke growing in Sardinia. However, it cannot be exc1uded the possible occurrence in artichoke plants of a latent carlavirus too.