A new trisubstituted derivative of phenylacetic acid methyl ester was isolated from a Pseudomonas syringae pv. papulans strain culture. It was characterized as the methyl ester of 2',5'-dihydroxy-3'-nitrophenylacetic acid by spectral studies of the metabolite and the corresponding diacetylderivative. The new metabolite modulates the growth of tomato seedlings.