HETEROLOGOUS ENCAPSIDATION IN NONTRANSGENIC AND TRANSGENIC NICOTIANA PLANTS INFECTED BY GRAPEVINE VIRUSES A AND B
N. Buzkan, A. Minafra, P. Saldarelli, A. Castellano, M. Dell’Orco, G.P. Martelli, R. Gölles, M. Laimer da Camara Machado
In mixed infections of Grapevine virus A (GVA) and Grapevine virus B (GVB) in non-transgenic Nicotiana plants, one-sided phenotypic mixing (GVA coat protein encapsidating GVB RNA) was detected by immunocapture- RT-PCR, with a frequency ranging from 33 to 75%. Immuno-electron microscopy confirmed the presence of both capsid proteins in the same virus particles. Heteroencapsidation took also place in R1 seedlings of transgenic Nicotiana lines expressing GVA or GVB coat proteins, when the plants were challengeinoculated with the heterologous virus. Finally, whole virus particles were produced when an infectious but CP-defective GVB RNA transcript was inoculated biolistically as a DNA plasmid into Nicotiana plants transgenically expressing GVB CP.