Phytohormone production by a strain of Pantoea agglomerans from knots on olive plants caused by Pseudomonas savastanoi pv. savastanoi

Pantoea agglomerans is a common epiphyte of many plant species, and it is assocd. with Pseudomonas savastanoi savastanoi in young and apparently intact olive knots. Strains of P. agglomerans collected from various olive groves in central Italy were studied for their ability to accumulate plant growth substances in culture. All the strains produced indole-3-aldehyde, indole-3-ethanol, and indole-3-acetic acid (IAA), this last compd. in amts. (av. 8.7 mg/L) comparable to those produced in vitro by virulent strains of P. savastanoi. None of the olive strains produced cytokinins. It is suggested that the IAA produced by P. agglomerans may increase the size of the knots caused on olive by P. savastanoi