Distribution of tobamovirus movement protein in infected cells and implications for cell‐to‐cell spread of infection

• Published in: The Plant journal : for cell and molecular biology Vol. 10; no. 6; pp. 1079 - 1088
• Main Authors: Padgett, Hal S., Epel, Bernard L., Kahn, Theodore W., Heinlein, Manfred, Watanabe, Yuichiro, Beachy, Roger N.
• Format: Journal Article
• Language: English
• Published: Osney Mead, Oxford OX2 0EL, UK Blackwell Science Ltd 01-12-1996; Blackwell Science
• Subjects: Biological and medical sciences; Biological Transport; Cell Compartmentation; Cell Wall - chemistry; Fundamental and applied biological sciences. Psychology; Green Fluorescent Proteins; Immunoblotting; Luminescent Proteins - genetics; Mutagenesis; Nicotiana - virology; Phytopathology. Animal pests. Plant and forest protection; Plant Diseases - virology; Plant Leaves - virology; Plant Viral Movement Proteins; Plant viruses and viroids; Plants, Toxic; Protoplasts - virology; Recombinant Fusion Proteins; Species Specificity; Systematics. Structure, properties and multiplication. Genetics; Tissue Distribution; tobamovirus; Tobamovirus - growth & development; Viral Proteins - isolation & purification; Viral Proteins - metabolism; Plant pathogen; Host agent relation; Tobamovirus; Plant leaf; Nicotiana tabacum; Viral movement protein; Virus; Proteins; Fluorescent labelling; Dicotyledones; Protoplast; Angiospermae; Distribution; Plasmodesm; Spermatophyta; Solanaceae; Experimental plant; Localization; Fluorescence microscopy
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1046/j.1365-313X.1996.10061079.x

Summary
The intercellular and intracellular distribution of the movement protein (MP) of the Ob tobamovirus was examined in infected leaf tissues using an infectious clone of Ob in which the MP gene was translationally fused to the gene encoding the green fluorescent protein (GFP) of Aequorea victoria. In leaves of Nicotiana tabacum and N. benthamiana, the modified virus caused fluorescent infection sites that were visible as expanding rings. Microscopy of epidermal cells revealed subcellular patterns of accumulation of the MP:GFP fusion protein which differed depending upon the radial position of the cells within the fluorescent ring. Punctate, highly localized fluorescence was associated with cell walls of all of the epidermal cells within the infection site, and apparently represents association of the fusion protein with plasmodesmata; furthermore, fluorescence was retained in cell walls purified from infected leaves. Within the brightest region of the fluorescent ring, the MP:GFP was observed in irregularly shaped inclusions in the cortical regions of infected cells. Fluorescent filamentous structures presumed to represent association of MP:GFP with microtubules were observed, but were distributed differently within the infection sites on the two hosts. Within cells containing filaments, a number of fluorescent bodies, some apparently streaming in cytoplasmic strands, were also observed. The significance of these observations is discussed in relation to MP accumulation, targeting to plasmodesmata, and degradation.