Fig 3. PglA is the major pectin degrading enzyme secreted by Xoo.

Wild type (Wt) Xoo and the four mutant strains, namely, pglA^- (polygalacturonase), pmt—(pectin methyl esterase), pel^- and pelL^- (both deficient in pectate lyases) were grown on polygalacturonic acid containing PSA medium, followed by ruthenium red staining. A halo around the bacterial colony is indicative of secretion of an active PGA degrading enzyme. Similar results were obtained in at least three independent experiments.