Choline promotes growth and tabtoxin production in a Pseudomonas syringae strain

Abstract

Some Pseudomonas syringae pathovars secrete tabtoxin, a monocyclic β-lactam antibiotic, responsible for chlorosis, the principal halo blight symptom in susceptible plants as oats, rye, barley, wheat and sorghum, among other. Here, we demonstrated that the production of tabtoxin in a P. syringae strain increased at least 150%, when choline, betaine or dimethylglycine were used as nitrogen source, or when choline was added as osmoprotectant in hyperosmolar culture media. Besides, we investigated the induction of phosphorylcholine phosphatase (PchP) activity when choline or its metabolites were used as nitrogen sources. PchP is an enzyme involved in Pseudomonas aeruginosa pathogenesis through its contribution to the breakdown of choline-containing compounds of the host cells. Considering these results and that the success of a pathogenic microorganism depends on its ability to survive and proliferate in its target tissue, we propose that choline is one of the plant signals that contribute to establishment of the infection by tabtoxin-producing strains of P. syringae.