THE MYRISTYLATION MOTIF OF PTO IS NOT REQUIRED FOR DISEASE RESISTANCE

The tomato Pto kinase confers resistance to bacterial speck disease ca used by strains of Pseudomonas syringae pv. tomato that express the av irulence gene avrPto. Pto contains a putative myristylation site at it s amino terminus that was hypothesized to play a role in localizing Pt o in the plant cell. Site-directed mutagenesis was used to change the invariant glycine residue in the myristylation motif to an alanine. Tr ansgenes encoding the mutant Pto(G2A) and wild-type Pto were placed be hind the cauliflower mosaic virus 35S promoter and transformed into to mato plants that are susceptible to bacterial speck disease. Both the mutant and wild-type forms of Pto conferred resistance to a strain of P. syringae pv. tomato expressing avrPto. These results indicate that the myristylation motif of Pto is not required for bacterial speck dis ease resistance.