Intracellular Location of Two Groundnut Rosette Umbravirus Proteins Delivered by PVX and TMV Vectors

• Published in: Virology (New York, N.Y.) N.Y.), 1998-03, Vol.242 (2), p.303-313
• Main Authors: Ryabov, E.V., Oparka, K.J., Santa Cruz, S., Robinson, D.J., Taliansky, M.E.
• Format: Article
• Language: English
• Subjects: Arachis - metabolism; Arachis - virology; Cell Nucleolus - metabolism; Cytoplasmic Granules - metabolism; Genetic Vectors; Green Fluorescent Proteins; Indicators and Reagents; Luminescent Proteins; Microscopy, Fluorescence; Plant Viruses - metabolism; Plant Viruses - pathogenicity; Potexvirus - genetics; Recombinant Fusion Proteins; RNA Viruses - metabolism; RNA Viruses - pathogenicity; Tobacco Mosaic Virus - genetics; Viral Proteins - physiology
• ISSN: 0042-6822; 1096-0341
• DOI: 10.1006/viro.1997.9025

The proteins encoded by open reading frames (ORF) 3 and 4 of groundnut rosette umbravirus (GRV) were expressed inNicotiana benthamianaas fusions with green fluorescent protein (GFP) from modified potato virus X (PVX) and tobacco mosaic virus (TMV) vectors. Regardless of which plant virus vector was used, GFP fused to the ORF3 protein accumulated in large cytoplasmic inclusion bodies and in nucleoli, whereas GFP fused to the ORF4 protein was found in cell walls close to plasmodesmata. Cell-to-cell movement of PVX requires three proteins encoded by the triple gene block (TGB) and also the coat protein (CP). However, when GRV ORF4 was substituted for the PVX CP gene, the hybrid virus was able to move normally in inoculated leaves but not into noninoculated leaves. In contrast, when GRV ORF4 was substituted for the TGB, or for both the TGB and the CP gene, movement of the hybrid viruses was limited to a few epidermal cells neighboring the infection site. Thus, the GRV ORF4 protein can replace the movement proteins of PVX for some of their functions.