Tobacco rattle virus mediated gene silencing in strawberry plants

Virus-induced gene silencing (VIGS) is an attractive reverse-genetics tool for studies of plant gene function; however, efficient VIGS has only been accomplished in a few plant species. In order to extend the application of VIGS, we examined whether the use of a VIGS vector based on the tobacco rattle virus (TRV) would result in phenotypic changes in strawberry (Fragaria x ananassa). In this study we successfully silenced the expression of a strawberry phytoene desaturase (PDS) gene (FaPDS) and showed a significant reduction in FaPDS mRNA levels correlated with a concomitant photobleached phenotype. The spread of the virus harboring the TRV vector containing the coding sequence of the green fluorescent protein (GFP) marker protein (TRV-GFP) virus was readily monitored using fluorescent microscopy and a hand-held UV lamp, such that the infiltrated plants could be screened by detecting the GFP fluorescence. We also demonstrated that post-agroinfiltration water culture is an effective means to enhance the viability of vacuum-infiltrated plants. Taken together, the results confirm that VIGS using the TRV/TRV-GFP vector represents a new potentially valuable tool for strawberry functional genomic studies.