Fig 4. Restoration of enzymatic activities by complementing strains.

A) The Wild type (Wt) Xoo strain, the pglA^- mutant, the pglA^- mutant with empty pHM1 vector and the pglA^- mutant with pHM1 having the pglA gene were patched on polygalacturonic acid containing PSA medium followed by ruthenium red staining. A halo around the bacterial growth is indicative of active PGA degrading enzyme secreted by the strain. B) The wild type (Wt) Xoo strain, the pmt^- mutant, the pmt^- mutant with empty pHM1 vector and the pmt^- mutant with pHM1 having pmt gene were patched on pectin containing PSA medium followed by ruthenium red staining. A red zone around the colony is indicative of de-esterification of pectin. Similar results were obtained in three independent experiments. For each complementing clone, three independent transformants were tested for restoration of enzymatic activity and all of them showed complementation.