Cell-to-cell and systemic movement of recombinant green fluorescent protein-tagged turnip crinkle viruses

To facilitate analyses of turnip crinkle virus (TCV) cell-to-cell and syste mic movement, we created a series of recombinant viruses expressing green f luorescent protein (GFP) either as substitutions of coat protein (CP) seque nces or as fusions to movement proteins (MPs). Constructs were used to inoc ulate leaves of Arabidopsis seedlings. TCV carrying its two native MPs and GFP fused near the start of CP translation (GFP Delta CP) resulted in cell- to-cell movement manifested by the expansion of fluorescent fool on inocula ted leaves. GFP fusions to either MP were inactive for movement. However, T CV carrying the p9-GFP fusion, which expresses a functional p8 gene, could be complemented for cell-to-cell movement by coinoculation with virus carry ing native p9 but mutant for p8. This same coinoculation combination also l ead to systemic spread of GFP fluorescence to noninoculated leaves, as the complementing virus carries native CP. Complementation for systemic movemen t of virus carrying GFP Delta CP constructs was achieved by inoculation ont o transgenic plants expressing TCV CP. GFP-tagged TCV movement was detected throughout the plant, including the inflorescence stem, cauline leaves, fl owers, siliques, and substructures such as organ primordia and meristematic regions. The recombinant viruses described herein provide (1) genetic info rmation relevant to define regions of TCV that can, or cannot, be manipulat ed by insertion of foreign coding sequences and (2) a set of tools to allow the study of viral cell-to-cell and long-distance movement in the model pl ant system Arabidopsis. (C) 2000 Academic Press.