Incidence and genetic variability of Asparagus virus 1 in naturally infected asparagus.

Abstract

A study to determine the incidence of viral diseases in green asparagus ( Asparagus officinalis L.) was carried out in Italy, sampling spears, young stems and ferns from com- mercial fields in several regions. Asparagus bunches from supermarkets originating from Italy as well as from sev- eral other countries, were also examined. Molecular assays (RT-PCR) were developed for the simultaneous detection of Asparagus virus 1 (AV-1) and Asparagus virus 2 (AV-2). The incidence of the two viruses was quite different. AV-2 was restricted to a few Italian cultivation areas and was never detected in samples from Spain, Peru, Mexico, Ec- uador, Argentina, or the USA. In contrast, AV-1 was widely spread in Italian asparagus crops with an average infection rate of about 50.7% and was detected in imported aspara- gus at different rates. Partial sequences of AV-1 isolates from different geographical areas were obtained. Their 3’ terminal genomic region comprising the partial coat protein gene and the 3’ untranslated region of 18 isolates were compared to each other and to species of the genus Potyvirus . Results revealed that AV-1 has become the most widespread virus in commercial asparagus crops of Italy, and presumably in other asparagus producing countries. Further, our study provides, for the first time, valuable information on the molecular variability of AV-1 isolates from different parts of the world.