The complete genome sequence for a Turkish isolate of <Emphasis Type="Italic">Wheat dwarf virus</Emphasis> (WDV) from barley confirms the presence of two distinct WDV strains

The complete genome for a barley isolate of Wheat dwarf virus (WDV) from Tekirdağ, Turkey, WDV-Bar[TR], was isolated and sequenced. The genome was found to be 2739 nucleotides long, which is shorter than wheat-infecting WDV isolates, and with a genome organization typical for mastreviruses. The complete genome of WDV-Bar[TR] showed 83–84% nucleotide identity to wheat isolates of WDV, with the non-coding regions SIR and LIR least conserved (72–74% identity). The deduced amino acid sequences for Rep and RepA were most conserved (92–93%), while CP and MP were less conserved (87% and 79–80%, respectively). The identity to other mastrevirus species was significantly lower. In phylogenetic analyses, the WDV isolates formed a distinct clade, well separated from the other mastreviruses with the wheat isolates grouping closely together. Phylogenetic analyses of WDV-Bar[TR], the partial sequence for another Turkish barley isolate (WDV-Bar[TR2]) and published WDV sequences further supported the division of WDV into two distinct strains. The barley strain could also be divided into three subtypes based on relationships and geographic origin. This study shows the first complete published sequence for a barley isolate of WDV. The nucleotide sequence data reported appear in the EMBL, GenBank and DDBJ Nucleotide Sequence Databases under the accession numbers AJ783960 and AJ811960.     

Ageratum conyzoides: a host to a unique begomovirus disease complex in Cameroon

Ageratum conyzoides (goat weed) is a widespread uncultivated species in Cameroon that exhibits leaf curl disease (LCD) symptoms suggestive of begomovirus infection. In Asia, different begomovirus-satellite complexes have been identified in A. conyzoides. The objective of this study was to determine the identity of the suspect begomoviruses and their associated satellites in A. conyzoides in Cameroon. The results indicated that all three symptomatic A. conyzoides plants examined were infected with a new begomovirus species, herein named Ageratum leaf curl Cameroon virus (ALCCMV). The ALCCMV genome sequences shared their highest identity, at 84.3-88.5%, with a group of tomato-infecting begomoviruses from West Africa. In addition, a betasatellite and an alphasatellite were cloned from the same symptomatic A. conyzoides plants. The betasatellite sequences shared limited sequence identity at 37% or less with the betasatellite Cotton leaf curl Gezira betasatellite, and the new betasatellite species is herein named Ageratum leaf curl Cameroon betasatellite (ALCCMB). The alphasatellite shared 80% nt identity with Tomato leaf curl Cameroon alphasatellite (ToLCCMA), and the new alphasatellite species is herein named Ageratum leaf curl Cameroon alphasatellite (ALCCMA). In addition, two fragments containing begomovirus-alphasatellite sequences were cloned from sample AGLI4, and they were related to the defecting interfering molecule (Y14167) associated with Ageratum yellow vein virus from Asia. These results suggest that the begomoviral-satellite complexes infecting A. conyzoides in Cameroon may be as complex or more so, to species and strains reported thus far from Asia.     

Molecular characterisation of Raspberry bushy dwarf virus isolates from Sweden and Belarus

The complete coding sequences were determined for RNA-1 and RNA-2 of five raspberry isolates of Raspberry bushy dwarf virus (RBDV) from Belarus (BY1, BY3, BY8, BY22) and Sweden (SE3). The analysed sequences for both RNA-1 and RNA-2 were highly conserved among these isolates. Phylogenetic analyses including available sequences for the CP gene and the MP gene showed that all analysed RBDV isolates from raspberry were closely related. However, there was no strong correlation between the grouping of raspberry isolates in the phylogenetic analyses and their geographical location. In contrast, RBDV isolates showed a host-dependent relationship with isolates from raspberry and grapevine, forming two distinct clades.