Expression of a modified nucleocapsid-protein of Tomato spotted wilt virus (TSWV) confers resistance against TSWV and Groundnut ringspot virus (GRSV) by blocking systemic spread

Tobacco transformed with a construct comprising the nucleocapsid-protein (N) gene of Tomato spotted wilt virus (TSWV) and the 5′ non-translated leader sequence of Plum pox virus (PPV) as a translation enhancer displays unusually broad resistance against tospoviruses. Contrary to expectations, the transgenic plants did not express a higher level of TSWV N protein than control plants harbouring the N gene without the PPV enhancer. Instead, expression of an N-terminally elongated N protein, due to the presence of an in-frame start codon in the PPV leader, was detected. This modified N protein was present in nucleocore and virion preparations and appears to confer resistance by interfering with systemic spread of the virus in the aerial parts of the transgenic plants, while not having an effect on primary replication.