EFFICIENT WHITEFLY TRANSMISSION OF AFRICAN CASSAVA MOSAIC GEMINIVIRUSREQUIRES SEQUENCES FROM BOTH GENOMIC COMPONENTS

Clones of two subgroup III geminiviruses, the common strain of tomato golden mosaic virus (csTGMV) and African cassava mosaic virus originat ing from Kenya (ACMV-K), were shown to be non-transmissible by whitefl ies. Lack of transmissibility of cloned ACMV-K was investigated by exc hanging genomic components with a whitefly-transmissible ACMV isolate from Nigeria (ACMV-NOg). Neither pseudorecombinant was transmissible, indicating that defects in both genomic components contributed to the lack of transmissibility. Analysis of the acquisition of the pseudorec ombinants by Bemisia tabaci indicated that accumulation of virus withi n the insect was DNA B dependent. Return of virus to plants was determ ined by DNA A, although the coat protein was essential for acquisition . Repeated passaging of both the wild strain of ACMV-NOg and the clone d virus led to loss of insect transmissibility of the wild isolate but not the cloned virus. Products encoded on both genomic components are required for transmission of bipartite geminiviruses by B. tabaci.