COMBINED EFFECTS OF AUXIN TRANSPORT INHIBITORS AND CYTOKININ - ALTERATIONS OF ORGAN DEVELOPMENT IN TOBACCO

We have examined the effects of the auxin transport inhibitors 1-napht hylphthalamic acid (NPA) and 2,3,5-triiodobenzoic acid (TIBA) on leaf morphogenesis of transgenic Nicotiana tabacum (cv. Xanthi) plants expr essing the Agrobacterium tumefaciens cytokinin biosynthetic gene, ipt. We have observed the formation of saucer-shaped leaflike organs at th e shoot apex and at lateral buds. The formation of apical saucer-shape d leaf-like organs can be duplicated by the application of exogenous N PA and cytokinin to wild-type tobacco seedlings. We have also observed adventitious leaf-like organs with altered petiole and blade morpholo gy in the transgenic plants treated with auxin transport inhibitors. T hese results suggest that the combination of diminished auxin transpor t and elevated cytokinin can lead to alterations in leaf development i n tobacco.