Resistance of plant to a wide variety of diseases depends on pathogen avirulence host resistance genes pair.In the present resarch avrPto genes were colonage on plasmid pLA2917 and then recombinant avrPto transferred to wild isolates of Pseudomanas syringae pv.tomato, P.s. pv. phaseolicola and P.s.pv. syringae by electroporation method. Then susceptible variety, cannery row (without Pto resistant genes) and resistant variety, caston (with Pto resistant gene) of tomato were inoculated by wild isolates and the isolates having pLA(avrPto) recombinant plasmid . The results indicate that there is no signficant difference in bacterial population dynamism on suceptible variety between wild isolates having recombinant plasmid. However, these isolates singificantly differ on the bacterial population dynamism on resistant variety.The effect of gene for gene theory was also noted on growth lengh of the plant. The growth length was sinificantly higher in resistant plant inoculated by recombinant plasmid isolates than those inoculated by wild isolates. On the whole, it is suggested that, in both cases, i.e. comatibility and incompatibility, the bacteria colonizes tomato plant but in a lower level in incompatible than in compatible interaction under field conditions.
)