Contents

26 November 1993
Vol 262, Issue 5138

About The Cover

Resistance genes are widely used to control plant diseases caused by bacteria, fungi, viruses, and nematodes. A single gene, Pto, encoding a protein kinase, confers resistance in tomato to the bacterial pathogen Pseudomonas syringae pv. tomato, as shown by the healthy leaves from genetically modified plants (diseased leaves are from susceptible, wild-type plants). The presence of Pto homologs in many crop species may expedite the isolation of other plant resistance genes. See page 1432. [Photo: Gregory B. Martin]