CBN-V Video Archives - S8-20
Detection, Relationships and Properties of Cassava Mosaic Geminivirus in Naturally Infected Castor Oil Plant, Ricinus comunis L. in Nigeria

Shoyinka S.A¹, G. Thottappilly², F.F. McGrath³ and B.D. Harrison³

1. Institute of Agricultural Research and Training, Obafemi Awolowo University, P.M,B. 5029, Moor Plantation, Ibadan, Nigeria s.shoyinka@cgiar.org
2. Mahyco Research Foundation, Biotechnology Centre, Hyderabad-500 073, A.P.
3. Virology Department, Scottish Crop Research Institute, Invergowrie, Dundee, UK

        A conspicuous mosaic disease of castor oil plant, Ricinus communis (Eupahobiaceae), in Nigeria was shown in immunosorbent electronmicroscopy (ISEM) to be a geminivirus, with particle sizes of 30x20nm and it was named castor mosaic geminivirus (CasMV). It was transmitted by the whitefly Bemisia tabaci and also by mechanical inoculation, using buffered sap, to Nicotiana benthamiana and castor. Using Triple Antibody Sandwich ELISA (TAS-ELISA), CasMV particles reacted with 23 monoclonal antibodies raised to particles of African cassava mosaic virus (ACMV) and Indian cassava mosaic virus (ICMV). CasMV shared 17 epitopes with ACMV and East African cassava mosaic virus (EACMV) and 6 epitopes with ICMV. CasMV has a narrow host range restricted to castor and N. Benthamiana from which cassava, (Manihot esculenta Crantz) was infected through return mechanical inoculation. Whiteflies, reared on Solanum melongena, were found to be inefficient vectors of CasMV either from castor to castor or from castor to N. benthamiana. Adult whiteflies acquired CasMV from infected castor plants and transmitted it at frequencies much less than the rate for its transmission from CasMV infected N.betnhamiana. The constitution of ACMV, EACMV and ICMV epitope profiles in one single host (Ricinus communis) suggests that there may not be a strict geographical demarcation in the distribution of the three viruses. This constitutes the first report of the occurrence of ACMV in R. communis.

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