Rice tungro bacilliform virus DNA independently infects rice after Agrobacterium-mediated transfer

Department of Virus Research, John Innes Institute, John Innes Centre for Plant Science Research, Colney Lane, Norwich NR4 7UH, U.K. In nature, rice tungro disease is caused by an RNA and a DNA virus complex, but we have obtained an independently infectious clone of rice tungro bacilliform virus (RTBV) DNA. Infectivity could be demonstrated only when a more than unit-length copy was cloned in the Agrobacterium binary vector Bin19 and agroinoculated into rice plants. Rice plants thus agroinfected with cloned RTBV DNA showed typical symptoms of tungro disease, presence of viral DNA and bacilliform particles, and could be used as a source of virus to infect healthy plants by the green leafhopper ( Nephotettix virescens ). The importance of this infectious clone in understanding the molecular biology of RTBV and the rice tungro disease is discussed. Present address: Instituto di Patologia Vegetale, Via Filippo Re 8, 40126 Bologna, Italy. Received 18 January 1991; accepted 27 February 1991.