PROTECTION AGAINST VIRUS-INFECTION IN TOBACCO PLANTS EXPRESSING THE COAT PROTEIN OF GRAPEVINE FANLEAF NEPOVIRUS

Grapevine fanleaf nepovirus (GFLV) is responsible for the economically significant ''court-noue'' disease in vineyards. Its genome is made u p of two single-stranded RNA molecules (RNA1 and RNA2) which direct th e synthesis of polyproteins P1 and P2 respectively. A chimeric coat pr otein gene derived from the C-terminal part of P2 was constructed and subsequently introduced into a binary transformation vector. Transgeni c Nicotiana benthamiana plants expressing the coat protein under the c ontrol of the CaMV 35S promoter were engineered by Agrobacterium tumef aciens-mediated transformation. Protection against infection with viri ons or viral RNA was tested in coat protein-expressing plants. A signi ficant delay of systemic invasion was observed in transgenic plants in oculated with virus compared Lo control plants. This effect was also o bserved when plants were inoculated with viral RNA. No coat protein-me diated cross-protection was observed when transgenic plants were infec ted with arabis mosaic virus (ArMV), a closely related nepovirus also responsible for a ''court-noue'' discase.