VIRAL SATELLITE RNA AS A BIOLOGICAL CONTROL AGENT FOR PLANTS

Biological control technology based on viral satellite mediated protection is a novel concept of the viral disease control strategies. Cucumber mosaic virus (CMV) is considered one of the most economically damaging viruses among field grown vegetables such as tomato (Solanum lycopersicum L). CMV can harbor molecular parasites known as satellite RNAs that dramatically alter the symptom phenotype induced by the virus. Two indigenous strains of CMV satellite RNA were isolated and have been sequenced. One of these strains designated as CMV‐KU1 reduced the viral disease to a virtually asymptomatic condition. The other strain was found to aggravate the symptoms and cause severe crop loss and tomato necrosis. Thus, satellites have been referred to as “natural inhibitors of crop damaging viruses’. These satellites RNAs are small nucleic acids whose nucleotide sequences are unrelated to, but are replicatively dependent upon the viral genome; they have a molecular parasitic relationship. Particularly, the KU1 strain may be used to protect plants against a particular viral strain of CMV, referred to as the KU2 strain. The attenuating properties of some satellite RNAs can be exploited to control viral diseases by preinoculating crops with an attenuating satellite RNA variant combined with virus. This technique can effectively protect against CMV disease in the field.