The use of a Tobacco mosaic virus-based expression vector system in chrysanthemum

Chrysanthemums (Chrysanthemum morifolium) are susceptible to tobacco mosaic virus (TMV). TMVbased expression vectors have been used in highthroughput experiments for production of foreign protein in plants and also expressing green fluorescent protein (GFP) to allow visualization of TMV movement. Here, we used TMV expressing the GFP to examine the infection of chrysanthemum by a TMVbased expression vector. Viral replication, movement and GFP expression by TMV-GFP were verified in upper leaves of chrysanthemums up to 73 days post inoculation (dpi) by RT-PCR. Neither wild-type TMV nor TMV-GFP induced symptoms. GFP fluorescence was seen in the larger veins of the inoculated leaf, in the stem above the inoculation site and in petioles of upper leaves, although there was no consistent detection of GFP fluorescence in the lamina of upper leaves under UV. Thus, a TMV-based expression vector can infect chrysanthemum and can be used for the in vivo study of gene functions.