Competition Between Cucumber Mosaic Virus Satellite RNAs in Tomato Seedlings and Protoplasts: A Model for Satellite-Mediated Control of Tomato Necrosis. C. R. Smith, Research Associate, Soybean and Alfalfa Research Laboratory. M. E. Tousignant, L. M. Geletka, and J. M. Kaper. Chemist, Biological Lab Technician, and Research Chemist, Microbiology and Plant Pathology Laboratory, Plant Sciences Institute, ARS, USDA, Beltsville, MD 20705. Plant Dis. 76:1270-1274. Accepted for publication 24 August 1992. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1992. DOI: 10.1094/PD-76-1270.

The competition between two satellite RNAs of cucumber mosaic virus (CMV) in inoculated tomato seedlings or in electroporated tomato protoplasts was examined using semidenaturing polyacrylamide gel electrophoresis and northern hybridization. Analysis of total nucleic acid extracts revealed that in infections with two simultaneously inoculated satellite RNAs, or in infections where the more virulent satellite was inoculated at a later time, the amount of the two satellite RNAs that accumulated differed. The amount of accumulation depended on the concentration of each satellite RNA in the inoculum and the length of time between inoculations. On the basis of symptomatological and molecular analyses, inoculation with CMV containing a mild satellite RNA prior to challenge by a severe satellite RNA with or without CMV interfered with the replication and symptom expression of the severe strain. These results support the feasibility of the use of mild virus-satellite combinations in the biocontrol of CMV.