The Nature of Root-Promoting Substances in Lycopersicon esculentum Seedlings.

Determination of the organ sites and chemical nature of root-promoting substances in Lycopersicon esculentum seedlings was made. Results of organ excision indicated that the young cotyledons were the primary site of root-promoting substances. As the cotyledon matured, its root-promoting activity decreased while that of the developing plumular leaves increased. Application of 2,3,5-triiodobenzoic acid (TIBA) at 10 ³ M in lanolin to the hypocotyl below the cotyledonary node significantly prevented root formation. Bioassay, using a new tomato rooting test, of the basic, acidic and bound fractions of the cotyledon extracts after paper chromatography showed biological activities in all three fractions. Gas-liquid chromatography of selected active regions of the paper chromatogram resulted in a partial tentative identification of indolepropionic acid, 5-methylindole, 5-hydroxyindole and 3-indoleacetonitrile. The combined evidence indicated that the root-promoting substances in tomato seedlings resemble auxin compounds. [ABSTRACT FROM AUTHOR]