Encapsidation and spread of African cassava mosaic virus DNA A in the absence of DNA B when agroinoculated to Nicotiana benthamiana

Agroinoculation of African cassava mosaic virus DNA A alone into Nicotiana benthamiana resulted in the occasional spread of viral DNA throughout the stem, leaves and root. The amount of DNA A reached 5% of that associated with full infection following agroinoculation of both DNAs A and B, although the plants remained asymptomatic. Detection of virus particles in the upper leaves indicates that DNA B is not essential for virus assembly. The predominant form of the virus-specific DNA was single-stranded, which is possibly encapsidated within the virus particles. Double-stranded DNA forms could also be detected in the upper leaves.