Cover photograph (Copyright © 2005, American Society for Microbiology. All Rights Reserved.): Secondary metabolites and virulence. Maize leaves were inoculated with a wild-type strain of the filamentous fungal plant pathogen Cochliobolus heterostrophus (right, large lesions, same leaf, displayed three times) and a mutant strain lacking a nonribosomal peptide synthetase-encoding gene (left, small lesions, same leaf, displayed three times). The mutant is reduced in virulence and is sensitive to oxidative stress. Maize inoculation was performed by Shinichi Oide. (Photo courtesy of Kent Loeffler, Department of Plant Pathology, Cornell University.) (See related article on page 545.)