Phytohormone Production by Strains of Pantoea agglomerans from Knots on Olive Plants Caused by Pseudomonas savastanoi pv. savastanoi

Abstract

Pantoea agglomerans is a common epiphyte of many plant species, and it is associated with Pseudomonas
savastanoi pv. 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 compound in amounts
(average 8.7 mg l-1) 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.