Università degli studi di Sassari, Facoltà di Agraria - Gallizzi
Abstract
A latent virus of artichoke has been isolated in Sardinia (Italy).
The virus causes characteristic local lesions on Gomphrena globosa L.
and Chenopodium amaranticolor Coste et Reyn., and systemic symptoms on
Nicotiana benthamiana Domin. and N. clevelandii Gray.
In artichoke crude sap the virus has a longevity in vitro of 20-30 hours,
a dilution-end point between 10-3 and 10-4 and 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/E260 of 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 inocu1ated Nicotiana benthamiana contained 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
