Comparative effects of some Amo-1618 analogs on gibberellin production in Fusarium moniliforme and on growth in higher plants

Abstract

The plant growth retardant 2-isopropyl-4-dimethylamino-5-methylphenyl-1-piperidinecarboxylate methyl chloride (Amo-1618) and three analogs (Carvadan, XII, XIII) were tested for ability to inhibit gibberellin production in Fusarium moniliforme and to suppress stem elongation in three species of higher plants. Amo-1618 and compound XII were highly effective in suppressing GA production in Fusarium whereas Carvadan and XIII were inactive. These inactive analogs were not degraded to any appreciable extent by Fusarium cultures. All four compounds suppressed stem growth although the relative effectiveness varied with the species tested. Carvadan was most active in dwarfing Phaseolus vulgaris and Pharbitis nil; compound XII was most active in Helianthus annuus. The lack of correlation between the ability to inhibit gibberellin production in Fusarium and to cause dwarfed growth in higher plants is interpreted to indicate that enzymes involved in gibberellin biosynthesis in different organisms exhibit certain variations which make them more or less sensitive to inhibitors such as the four growth retardants tested.