Cover photograph (Copyright © 2002, American Society for Microbiology. All Rights Reserved.): Photograph, taken under long-wavelength UV light, of a transgenic green fluorescent protein (GFP) transgene-containing Nicotiana benthamiana leaf infiltrated with two strains of Agrobacterium tumefaciens, one carrying a plasmid coding for GFP and the other carrying a plasmid coding for the P0 protein of beet western yellows virus. The posttranscriptional gene silencing suppressor activity of the P0 protein results in overexpression of GFP in the infiltrated zone. (See related article on page 6815.)