Imaging the green fluorescent protein in plants ? viruses carry the torch

Abstract

The green fluorescent protein (GFP) was introduced into plant cells using potato virus X as a vector. The GFP was produced at high levels within virus-infected cells by utilising a duplication of the viral coat protein subgenomic RNA promoter sequence to direct transcription of mRNA encoding the GFP. We also exploited the ability of GFP to retain its fluorescence when fused to other proteins by fusing it to the PVX coat protein. The resultant fluorescent virus became systemic and its movement from cell to cell was traced using confocal laser scanning microscopy. Using PVX as the vector, additional fusions of the GFP were made to the movement protein of tobacco mosaic virus (TMV). The fluorescent fusion protein produced was targeted to specific wall sites thought to be plasmodesmatal pit fields. The utility of virus-based vectors for the delivery and targeting of GFP in living plant cells is discussed.