Arch Virol (1998) 143: 2487–2492
Infectivity of African cassava mosaic virus clones
to cassava by biolistic inoculation
R. W. Briddon, S. Liu, M. S. Pinner, and P. G. Markham
Department of Virus Research, John Innes Centre, Norwich, U.K.
Accepted May 27, 1998
Summary. Clones of an African cassava mosaic virus isolate originating from
Nigeria (ACMV-NOg) were shown to be infectious to cassava by biolistic
inoculation. The production of pseudorecombinants between ACMV-NOg and
clones of an ACMV isolate originating from Kenya (ACMV-K) indicated that
the lack of infectivity of ACMV-K to cassava was due to defect(s) in the DNA B
genomic component; this component encodes two proteins involved in cell-to-cell
movement. This is the ﬁrst demonstration of infectivity of a cloned geminivirus
to cassava and conclusively proves that ACMV is the causative agent of cassava
mosaic disease. The potential uses of infectious ACMV clones and the means by
which to introduce them into cassava are discussed.
Cassava (Manihot esculenta Crantz) is a major source of carbohydrate for human
consumption throughout the tropics, but particularly in Africa . Africa is the
largestsingle producer of cassava, the majority of which is produced by traditional
farmers on a subsistence basis.
Cassava mosaic disease is the most important and devastating disease of cas-
sava in Africa. At the present time a particularly severe epidemic of the disease is
sweeping across central and eastern Africa . Cassava mosaic disease is caused
by a virus of the genus Begomovirus (previously called Subgroup III) in the family
Geminiviridae . African cassava mosaic virus (ACMV; previously also known
as cassava latent virus) is typical of the whiteﬂy-transmitted geminiviruses in
having two genomic components . The larger of the two components (DNA
A) encodes the coat protein and all viral functions required for viral replication.
Thus ACMV DNA A is capable of autonomous replication and encapsidation but
is unable to yield a full systemic infection . The second component (DNA B)