Reduction in Symptom Expression of Belladonna Mottle Virus Infection on Tobacco Plants by Boron Supply and the Antagonistic Action of Silicon

Boron and silicon have a dramatic influence on the expression of symptoms caused by plant virus infections. For tobacco plants, boron decreases and silicon enhances symptom expression after belladonna mottle virus infection. Infected leaf tissues are highly enriched on both trace elements. Boron supply stimulates the silicon accumulation. In the applied concentrations the trace elements have no phytotoxic effects on the host. Except endogeneous β-interferones, this could be the first example of antiviral action without any cytotoxicity.