Biological and molecular characterization of Dahlia mosaic caulimovirus
Creators: name: Pahalawatta, Vihanga
Publisher: name: Washington State University
Year: 2007
Subjects: Dahlia mosaic virus -- Genetics

description: Dahlia is an economically important ornamental crop in the USA and several countries
description: around the world. Among the viral diseases that affect dahlia, Dahlia mosaic virus (DMV), is
description: considered to be the most widespread and to have the greatest impact on flower production.
description: Molecular characterization of DMV showed the association of two distinct caulimoviruses
description: (DMV-D10, DMV-Portland) and a D10-like sequence variant (DMV-Holland) with the disease.
description: The genome structure and organization of DMV-D10 was determined. The double stranded
description: DNA genome shared many features with the members of the genus Caulimovirus. However,
description: sequence identity of various open reading frames of DMV-D10 with known caulimoviruses
description: ranged from 32-70% at amino acid level suggesting that D10 is a distinct caulimovirus.
description: Moreover, the aphid transmission factor was absent and the coat protein was smaller than that
description: found in other Caulimovirus species. Phylogenetic analysis using amino acid sequences from the
description: different protein coding regions indicated that DMV-D10 is closely related to DMV-Portland and
description: Figwort mosaic virus.
description: A PCR-based assay was used to determine the relative incidence of DMV-D10, DMVPortland
description: and DMV-Holland in dahlia samples from the USA and the Netherlands. Results indicated that DMV-D10 was present in 87.4% of samples from the USA and 97.6% of the
description: samples from the Netherlands. Furthermore, 97.6% of samples from the Netherlands were
description: positive for DMV-Holland while only 31.9% of the samples from the USA were positive. The
description: presence of DMV-Portland in samples from both the USA and the Netherlands was
description: comparatively less. The presence of all three DMV sequences in 36.6% of the dahlia samples
description: from the Netherlands and 6.7% of the dahlia samples from the USA highlighted the importance
description: of testing for all three sequences for DMV diagnostics. The distribution of DMV in the dahlia
description: seed was determined by PCR. The viral genome was detected in cotyledons. Seedlings from
description: grow-out tests were also positive for DMV-D10 indicating that the virus is seed transmitted. The
description: virus was also detected in the pollen collected from infected plants.
description: Viruses in certain genera in family Caulimoviridae were shown to integrate their genomic
description: sequences into their host genomes and exist as endogenous pararetroviral sequences. However,
description: members of the genus Caulimovirus remained to be an exception and are believed to exist only
description: as episomal elements during virus infection cycle. Using DMV-D10 specific probes, Southern
description: blot hybridization of total plant DNA from dahlia seedlings showed the presence of viral DNA in
description: the host DNA whereas, viral DNA was not detected in other known hosts of DMV. This is the
description: first report of natural integration of a caulimovirus genome into its host and existence of a
description: caulimovirus species as an endogenous pararetroviral sequence in a host plant. Epidemiological
description: and molecular properties of DMV-D10 would facilitate devising management options for
description: reducing the impact of the virus.