CONTENT OF INDOLEACETIC-ACID AND ITS METABOLISM IN ROOT-NODULES OF MELILOTUS-ALBA

The root nodules of Melilotus alba, a leguminous fodder herb, contain a high amount of indoleacetic acid (IAA). The tryptophan pool present in the nodule might serve as a source for the IAA production. Metaboli sm of IAA in the nodules was evidenced by the presence of IAA-metaboli zing enzymes, IAA oxidase and peroxidase. A high amount of IAA was pro duced by the symbiont isolated from the nodules in culture, when suppl emented with tryptophan. For IAA production, the bacteria preferred th e L-isomer over the DL- or D-isomer of tryptophan. The possible role o f nodular IAA production on the legume-Rhizobium symbiosis is discusse d.