Downregulation of a Pathogen-Responsive Tobacco UDP-Glc:Phenylpropanoid Glucosyltransferase Reduces Scopoletin Glucoside Accumulation, Enhances Oxidative Stress, and Weakens Virus Resistance Article, publication date, and citation information can be found at www.plantcell.org/cgi/doi/10.1105/tpc.010