Identification of a 334-ribonucleotide viral satellite as principal aetiological agent in a tomato necrosis epidemic.
Cucumber mosaic virus (CMV), a widespread and economically important virus of vegetable crops, often contains a satellite RNA, here designated CARNA-5 (for CMV-associated RNA 5). Viral satellites are small nucleic acids that are sequence-unrelated to, but replicatively dependent upon, the viral genome. They essentially are molecular parasites of their helper viruses, and thereby frequently modulate viral symptom expression. Some isolates of CARNA-5 change normally moderate CMV symptoms in tomato into a lethal disease named tomato necrosis; others ameliorate CMV symptoms in tomato and other important crop plants. Here we report on the identification and molecular characterization of a 334-nucleotide necrogenic CARNA-5 isolated from tomato fields in southern Italy, where a massive outbreak of lethal necrosis occurred in the summer of 1988. This is the first time that direct evidence is given for the involvement of a viral satellite in a crop disease of epidemic scale. The possible molecular interrelationships between plant, virus, satellite and other factors that influence the satellite-induced symptom modulation underlying such a catastrophe are discussed.
Kaper
J M
JM
Microbiology and Plant Pathology Laboratory, US Dept. of Agriculture, Beltsville, MD 20705.
Gallitelli
D
D
Tousignant
M E
ME
D005638:Fruit; D009029:Mosaic Viruses / Q000302:isolation & purification* / Q000472:pathogenicity; D010935:Plant Diseases; D012367:RNA, Viral / Q000302:isolation & purification*
D012367:RNA, Viral