Genetic variability and population structure of Grapevine leafroll-associated virus 3 isolates

Abstract

The genetic variability and population structure of a collection of 45 Grapevine leafroll-associated virus 3 (GLRaV-3) isolates were studied by single-stranded conformation polymorphism (SSCP) and sequence analysis of the RNA-dependent RNA polymerase (RdRp), heat-shock protein 70 homologue (HSP-70) and coat protein (CP) genes. The distribution of SSCP profiles was not correlated with the geographical origin of the isolates, indicating that GLRaV-3 is a single, undifferentiated population. The majority of the isolates showed an SSCP profile and a population structure that were composed of a single predominant variant. However, 10 % of the isolates for the RdRp and HSP-70 genes and 15 % for the CP gene were composed of a combination of two or more variants. Estimation of genetic diversity and phylogenetic analysis disclosed the possible existence of vines with mixed infections by diverging sequence variants, showing, in some cases, possible recombination events. Furthermore, differences in the genetic diversity and constraints existing in the three regions analysed indicated a higher variability in the CP gene. The epidemiological and biological implications of this finding are discussed.

Variability of the coat protein gene of Grapevine leafroll-associated virus 3 in Brazil

“…The Pet-1 isolate showed 100% of amino acid identity with Dawanhong Nº2, and Pet-1, -2 and -3 isolates were phylogeneticaly closer to Dawanhong Nº2, SL10 and NY1 isolates than to the Pet-4 isolate ( Figure 1B), demonstrating a lack of correlation between sequence identity and geographic origin. This was also observed by Turturo et al (2005) for GLRaV-3 isolates. This virus has a slow-movement, low transmission efficiency vector, and is spread mainly by contaminated propagative material rather than by mealybug transmission (Gugerli, 2003).…”

“…However, the natural occurrence of GLRaV-3 variants and the little sequence information available for this virus may limit the use of these techniques (Turturo et al, 2005).…”

Detection and molecular characterization of Egyptian isolates of grapevine viruses

“…Growing certified grapevines can reduce the incidence of mixed infections and thus prevent new disease outbreaks in grape-growing regions with diverse climatic, environmental and soil conditions. It was reported that the genomic diversity of GLRaV-3 has been examined based on the analysis of partial or complete heat shock protein 70 gene (HSP70) (Turturo et al, 2005;Fuchs et al, 2009). It was reported that the genomic diversity of GVA has been examined based on the analysis of partial or complete coat protein gene (CP), because it had a certain degree of variability (Goszczynski and Jooste, 2003;Murolo et al, 2008).…”

Rapid detection of Grapevine leafroll-associated virus type 3 using a reverse transcription loop-mediated amplification method

“…Studies of the genetic diversity of GLRaV-3 has shown that GLRaV-3 can be separated into five phylogenetic groups (Turturo et al, 2005;Jooste et al, 2010;Gouveia et al, 2011;). These groups do not seem to be geographically isolated and Group 1 isolates seem to be the most prevalent (Turturo et al, 2005). Initially it was thought that GLRaV-3 was only spread through the use of infected plant propagation material; however it is now known that several species of mealybugs and scale insects act as semipersistent vectors for the virus with varying efficiencies (Cabaleiro and Segura, 1997a;Fuchs et al, 2009a;Golino et al, 2002;Walton, 2004).…”

“…GLRaV-3 is part of the Closteroviridae family, where it is type species for the Ampelovirus (Martelli et al, 2002). Studies of the genetic diversity of GLRaV-3 has shown that GLRaV-3 can be separated into five phylogenetic groups (Turturo et al, 2005;Jooste et al, 2010;Gouveia et al, 2011;). These groups do not seem to be geographically isolated and Group 1 isolates seem to be the most prevalent (Turturo et al, 2005).…”