The Ptr1 Locus of Solanum lycopersicoides Confers Resistance to Race 1 Strains of Pseudomonas syringae pv. tomato and to Ralstonia pseudosolanacearum by Recognizing the Type III Effectors AvrRpt2 and RipBN

Race 1 strains of pv. , which cause bacterial speck disease of tomato, are becoming increasingly common and no simply inherited genetic resistance to such strains is known. We discovered that a locus in , termed ( ), confers resistance to race 1 pv. strains by detecting the activity of type III effector AvrRpt2. In , AvrRpt2 degrades the RIN4 protein, thereby activating -mediated immunity. Using site-directed mutagenesis of AvrRpt2, we found that, like , activation of requires AvrRpt2 proteolytic activity. also detected the activity of AvrRpt2 homologs from diverse bacteria, including one in . The genome sequence of revealed no homolog in the region. could play an important role in controlling bacterial speck disease and its future cloning may shed light on an example of convergent evolution for recognition of a widespread type III effector.