A PVY isolate infecting Ranunculus

Since 1983 a potyvirus was repeatedly isolated from Ranunculus asiaticus crops growing in Liguria (Northern Italy). The infected plants had more or less marked leaf chlorosis and deformations, depending on the combinations with other viruses, or appeared symptomless. The potyvirus was transmitted to six species belonging to two different families: Chenopodiaceae and Solanaceae. In fact it induced local lesions in C. amaranticolor, C. quinoa and C. album; it produced systemic mottling in Solanum tuberosum and Physalis floridana and occasional symptomless infection in Nicotiana tabacum 'White Burley'. TIP was between 70 and 73°C, DEP between 10⁻⁴ and 10⁻⁵, LIV at room temperature was between 4 and 5 days, and at 4°C approximately 3 weeks. The virus was purified from C. amaranticolor infected leaves by clarifiction with 30% chloroform and using an extraction buffer with a basic pH. The purified virus had a nucleoprotein UV absorption profile with a maximum at 260 nm, and a minimum at 244 nm. The modal length of the flexuous particles was close to 750 nm. Pinwheels, scrolls, tubes, laminated aggregates and bundles were observed in cytoplasm of infected Ranunculus and C. amaranticolor plants. In the immunoelectronmicroscopy test the potyvirus strongly reacted with PVY antiserum; partial decoration occurred with bearded iris mosaic virus (BIMV) serum. This is the first report of PVY in Ranunculus. In coltivazioni di Ranunculus asiaticus della Liguria è stato ripetutamente isolato dal 1983 un virus flessuoso appartenente al gruppo Poty. Le piante infette mostravano clorosi più o meno evidenti, deformazioni a livello fogliare ed in alcuni casi apparivano senza sintomi. La gravità delle alterazioni osservate era sovente in rapporto con la presenza di altre entità virali associate a quella in oggetto. Il virus è risultato trasmissibile meccanicamente solo a Chenopodiacee e Solanacee: ha indotto infatti sintomi locali su C. amaranticolor, C. quinoa e C. album, ha infettato in maniera sistemica Solanum tuberosum e Physalis floridana ed ha sporadicamente prodotto infezione in Nicotiana tabacum 'White Burley'. TIP è risultato compreso fra 70 e 73°C, DEP compreso fra 10⁻⁴ e 10⁻⁵, LIV a temperatura ambiente è stato di 4-5 giorni ed a 4°C di circa tre settimane. Il virus è stato purificato da foglie di C. amaranticolor mediante chiarificazione con 30% di cloroformio utilizzando un tampone di estrazione a pH basico; la lettura in UV ha permesso di individuare un massimo a 2