Transgenic tobaccos transformed with a gene encoding a truncated form of the coat protein of tomato black ring nepovirus are resistant to viral infection

 Tomato black ring virus (TBRV) belongs to the nepoviruses, an important genus of phytoviruses characterized by isometric particles and by their transmission by longidorid nematodes. As for all other nepoviruses, the coat protein (CP) of TBRV is encoded by the 3′ terminal part of the viral RNA2 (positions 2801–4334). A hybrid gene driving the expression of a truncated form of the TBRV CP was constructed. It contains a frameshift deletion at position T₄₀₆₅ so that in the encoded protein the last 90 amino acids of the wild-type CP are replaced by 52 amino acids encoded by a different reading frame of the viral RNA. This hybrid gene was introduced into the genome of Nicotiana tabacum cv 'Xanthi' plants. When compared to control plants, progeny of some transformants expressing the mutated CP gene (CPm+ plants) showed resistance against TBRV infection. This resistance is characterized by a delay in the appearance of symptoms, a reduction in the number of infected plants and a reduction in virus accumulation. Received: 28 February 1997 / Revision received: 1 August 1997 / Accepted: 24 March 1999