A Unique Virus Complex Causes Ageratum Yellow Vein Disease

Ageratum conyzoides L., a weed species widely distributed throughout southeast Asia, frequently exhibits striking yellow vein symptoms associated with infection by Ageratum yellow vein virus (AYVV), a member of the Germiniviridae (genus Begomovirus). Most begomoviruses have bipartite genomes (DNAs A...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2000-06, Vol.97 (12), p.6890-6895
Main Authors: Saunders, Keith, Bedford, Ian D., Briddon, Rob W., Markham, Peter G., Wong, Sek Man, Stanley, John
Format: Article
Language:English
Subjects:
Ageratum conyzoides
Ageratum yellow vein virus
Asia
Base Sequence
Biological Sciences
Botany
Curl
Disease
Disease transmission
DNA
DNA probes
DNA Replication
DNA, Circular - analysis
DNA, Viral - chemistry
Flowers & plants
Geminiviridae - genetics
Infections
Molecular Sequence Data
Nucleotides
Plant Diseases - virology
Symptoms
Vascular diseases
Viral DNA
Virus Replication
Viruses
Weeds
yellow vein
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Summary:Ageratum conyzoides L., a weed species widely distributed throughout southeast Asia, frequently exhibits striking yellow vein symptoms associated with infection by Ageratum yellow vein virus (AYVV), a member of the Germiniviridae (genus Begomovirus). Most begomoviruses have bipartite genomes (DNAs A and B), but only a DNA A has been identified for AYVV. We demonstrate that yellow vein disease of A. conyzoides results from co-infection by AYVV DNA A (2,741 nt) and a circular DNA that is approximately half its size (1,347 nt) that we designate DNA β . Apart from the sequence TAATATTAC, common to all geminiviruses and containing the initiation site of rolling circle replication, DNA β shows negligible sequence homology either to AYVV DNA A or to DNA B associated with bipartite begomoviruses. DNA β depends on DNA A for replication and is encapsidated by DNA A-encoded coat protein and so has characteristics of a DNA satellite. However, systemic infection of A. conyzoides by DNA A alone is sporadic and asymptomatic, and DNA A accumulation is reduced to 5% or less of its accumulation in the presence of DNA β . Therefore, DNA A and DNA β together form a previously unrecognized disease-inducing complex. Our data also demonstrate that the nanovirus-like DNA 1 component associated with infected A. conyzoides plays no essential role in the disease and represents a satellite-like DNA. Furthermore, the satellite DNA previously found associated with tomato leaf curl virus is probably a defective DNA β homologue.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.97.12.6890