In gene silencing, specific mechanisms are involved in transcript degradation or inhibition of transcription and the outcome is inhibition of translation and no protein expression. In most living organisms, gene silencing is an innate mechanism in regulation of translation and in defense against pathogens such as viruses. Recently, innovative researches have been carried out on topical application of small RNAs which can be taken up by plants and pathogens. This approach triggered gene silencing against some plant pathogens and conferred resistance to the sprayed plants. Although scientists have introduced resistant varieties to viruses via genetic transformation, on one hand, genetic modification and traditional plant breeding are time-consuming and demand colossal costs. On the other hand, there is public concern over genetically modified organisms. Altogether, application of small RNA sprays to confer resistance or to alter plant traits without genetic manipulation, opens new horizons of plant genetic engineering for scientists. In this paper, the latest achievements of scientists in application of such sprays to control plant viruses have been discussed.
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