A SELECTIVE AUXIN AND CYTOKININ BIOASSAY BASED ON ROOT AND SHOOT FORMATION IN-VITRO

A new bioassay for auxins and cytokinins was developed based on de nov o organogenesis. Auxin-dependent adventitious roots and cytokinin-depe ndent adventitious shoots were induced selectively in tobacco leaf dis c culture incubated on nutritive-medium for 28 days. All auxins applie d alone (indole, naphthalene, and phenoxyacetic acids) initiated roots , and all cytokinins used alone (purine and urea derivatives) initiate d shoots at a concentration range of about 10(-9) M-10(-4) M. The bioa ssay separated the effects of auxins and cytokinins eliminating their synergistic effects. Abscisic acid and gibberellin (GA(3)) had no morp hogenic activity.*