Huet, H., ILTAB, (IRD-DPSC), TSRI, 10550 N. Torrey Pines Road, San Diego, CA 92037, United States, ARO, Volcani Center, PO Box 6, Bet-Dagan, 50250, Israel
Mahendra, S., Malaysian Agric. Res. Devmt. Inst., PO Box 12301, Kuala Lumpur, Malaysia
Wang, J., ILTAB, (IRD-DPSC), TSRI, 10550 N. Torrey Pines Road, San Diego, CA 92037, United States
Sivamani, E., ILTAB, (IRD-DPSC), TSRI, 10550 N. Torrey Pines Road, San Diego, CA 92037, United States
Ong, C.A., Malaysian Agric. Res. Devmt. Inst., PO Box 12301, Kuala Lumpur, Malaysia
Chen, L., ILTAB, (IRD-DPSC), TSRI, 10550 N. Torrey Pines Road, San Diego, CA 92037, United States, Novartis Agric. Discovery Institute, 3050 Science Park Road, San Diego, CA 92121, United States
De Kochko, A., ILTAB, (IRD-DPSC), TSRI, 10550 N. Torrey Pines Road, San Diego, CA 92037, United States
Beachy, R.N., ILTAB, (IRD-DPSC), TSRI, 10550 N. Torrey Pines Road, San Diego, CA 92037, United States
Fauquet, C., ILTAB, (IRD-DPSC), TSRI, 10550 N. Torrey Pines Road, San Diego, CA 92037, United States

Rice tungro disease is caused by rice tungro bacilliform virus (RTBV), which is responsible for the symptoms, and rice tungro spherical virus (RTSV), which assists transmission of both viruses by leafhoppers. Transgenic japonica rice plants (Oryza sativa) were produced containing the RTSV replicase (Rep) gene in the sense or antisense orientation. Over 70% of the plants contained one to five copies of the Rep gene, with integration occurring at a single locus in most cases. Plants producing anti-sense sequences exhibited significant but moderate resistance to RTSV (60%); accumulation of antisense RNA was substantial, indicating that the protection was not of the homology-dependent type. Plants expressing the full-length Rep gene, as well as a truncated Rep gene, in the (+)-sense orientation were 100% resistant to RTSV even when challenged with a high level of inoculum. Accumulation of viral RNA was low, leading us to conclude that RTSV Rep-mediated resistance is not protein-mediated but is of the cosuppression type. Resistance was effective against geographically distinct RTSV isolates. In addition, RTSV-resistant transgenic rice plants were unable to assist transmission of RTBV. Such transgenic plants could be used in an epidemiological approach to combat the spread of the tungro disease.