TOMATO-PRF IS A MEMBER OF THE LEUCINE-RICH REPEAT CLASS OF PLANT-DISEASE RESISTANCE GENES AND LIES EMBEDDED WITHIN THE PTO KINASE GENE-CLUSTER

In tomato, resistance to Pseudomonas syringae pv. tomato (Pst) strains expressing the avirulence gene avrPto requires the presence of at lea st two host genes, designated Pto and Prf. Here we report that Prf enc odes a protein with leucine-zipper, nucleotide-binding, and leucine-ri ch repeat motifs, as are found in a number of resistance gene products from other plants. prf mutant alleles (4) were found to carry alterat ions within the Prf coding sequence. A genomic fragment containing Prf complemented a prf mutant tomato line both for resistance to Pst stra ins expressing avrPto and for sensitivity to the insecticide Fenthion. Prf resides in the middle of the Pto gene cluster, 24 kb from the Pto gene and 500 bp from the Fen gene.