Growth regulators, Rhizobium and nodulation in peas : Indole-3-acetic acid from the culture medium of nodulating and non-nodulating strains of R. leguminosarum.

Indole-3-acetic acid (IAA) has been identified in the culture medium of nodulating and non-nodulating strains of Rhizobium lebuminosarum by gas chromatography-mass spectrometry. The levels of IAA produced by the different strains have been quantified using multiple ion monitoring and a deuterated internal standard. Indole-3-acetic acid is produced in the absence of exogenous tryptophan in all strains but its level is greatly stimulated by applied tryptophan. No correlation has been established between the ability to nodulate peas and the ability to produce IAA.