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CBN-V Video Archives - S8-09
PCR-based Diagnostics Characterize the Effects of Cassava Mosaic
Geminiviruses on Yield and Cassava Mosiac Disease Epidemiology in
Uganda
Legg J.P 1,2,
B. Owor1 and G. Okao-Okuja1
1. International Institute of Tropical Agriculture – Eastern and
Southern Africa Regional Centre, PO Box 7878, Kampala, Uganda
JLEGG@INFOCOM.CO.UG
2. Natural Resources Institute, Greenwich University, Central
Avenue, Chatham Maritime, Kent, ME4 4TB, United Kingdom
Cassava Mosaic Geminiviruses (CMGs) are the causal agents of cassava
mosaic virus disease (CMD), which is arguably the most important
current constraint to cassava production in sub-Saharan Africa. From
the late 1980s to the present day, a major pandemic of unusually
severe CMD has spread throughout East and Central Africa, causing
massive losses and impacting the region’s food security. A novel
recombinant CMG, the Uganda Variant of East African Cassava Mosaic
Virus (EACMV-Ug) was shown to be associated with the pandemic,
commonly in mixed infection with the previously occurring African
Cassava Mosaic Virus (ACMV). Different viruses, virus strains and
mixtures have important effects on severity of symptom expression
and through this on yield. As a result, it is becoming increasingly
important to diagnose viruses/virus strains present within plants
used in field trials. This paper describes how PCR-based diagnostic
tools are now being used routinely to determine the effects of
specific virus/virus strain combinations on cassava yield and their
interactions in the epidemiology of CMD. One of the first results of
this work has been the field-based demonstration of how EACMV-Ug,
through its synergistic interaction with ACMV, promotes the
replication and vector-borne spread of ACMV. This leads to the rapid
colonization of susceptible cassava crops by both viruses in mixed
infection, a situation that mimics the characteristics of the
so-called ‘front’ of the CMD pandemic.
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Donald Danforth Plant Science Center All rights reserved.
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