Journal of General Virology (2009) 90, 1001-1013

Tatsuya Kon, Maria R. Rojas, Issoufou K. Abdourhamane and Robert L. Gilbertson (2009)
Roles and interactions of begomoviruses and satellite DNAs associated with okra leaf curl disease in Mali, West Africa
Journal of General Virology 90 (4), 1001-1013
Abstract: Okra leaf curl disease (OLCD) is a major constraint on okra (Abelmoschus esculentus) production in West Africa. Two monopartite begomoviruses (okra virus-1 and okra virus-2), a betasatellite and a DNA1 satellite are associated with OLCD in Mali. Okra virus-1 is an isolate of okra yellow crinkle virus (OYCrV), okra virus-2 is a recombinant isolate of cotton leaf curl Gezira virus (CLCuGV) and the betasatellite is a variant of cotton leaf curl Gezira betasatellite (CLCuGB). Cloned DNA of OYCrV and CLCuGV were infectious and induced leaf curl symptoms in Nicotiana benthamiana plants, but did not induce OLCD in okra. However, when these clones were individually co-inoculated with the cloned CLCuGB DNA, symptom severity and viral DNA levels were increased in N. benthamiana plants and typical OLCD symptoms were induced in okra. The CLCuGB was also replicated by, and increased symptom severity of, three monopartite tomato-infecting begomoviruses, including two from West Africa. The sequence of the DNA1 satellite was highly divergent, indicating that it represents a distinct West African lineage. DNA1 replicated autonomously, and replication required the DNA1-encoded Rep protein. Although DNA1 reduced helper begomovirus DNA levels, symptoms were not attenuated. In the presence of CLCuGB, DNA levels of the helper begomoviruses and DNA1 were substantially increased. Together, these findings establish that OLCD in Mali is caused by a complex of monopartite begomoviruses and a promiscuous betasatellite with an associated parasitic DNA1 satellite. These findings are discussed in terms of the aetiology of OLCD and the evolution of new begomovirus/satellite DNA complexes.
The GenBank/EMBL/DDBJ accession numbers of the sequences reported in this paper are EU024119 (okra yellow crinkle virus-[Mali:2006]), EU024120 (cotton leaf curl Gezira virus-Mali [Mali:Okra:2006]), EU024121 (cotton leaf curl Gezira betasatellite-[Mali:Okra:2006]) and EU589450 (okra leaf curl disease associated DNA1).
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
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Database assignments for author(s): Robert L. Gilbertson

Research topic(s) for pests/diseases/weeds:
general biology - morphology - evolution
molecular biology - genes

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Cotton leaf curl Gezira virus	Okra and relatives (Abelmoschus)	Mali
	Okra yellow crinkle virus	Okra and relatives (Abelmoschus)	Mali