Stable genetically engineered bacterial strains that overproduce coronatine are provided. The stable strains can be successfully cultivated to overproduce coronatine at temperatures that are suitable for large scale, commercial preparations of coronatine. The overproducing strains are also non-pathogenic. An exemplary strain is Pseudomonas syringae APV1, which successfully overproduces coronatine at 26.degree. C. Methods of optimizing culture conditions for coronatine production from the novel stable overproducing strains are provided, as are methods for using the overproducing strains to induce abscission and increase taxane production.