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-naphthylphthalamic acid (NPA) and 2,3,5-triiodobenzoic acid (TIBA) on leaf morphogenesis of transgenic Nicotiana tabacum (cv.Xanthi) plants expressing the Agrobacterium tumefaciens cytokinin biosynthetic gene, ipt.We have observed the formation of saucer-shaped leaflike organs at the shoot apex and at lateral buds.The formation of apical saucer-shaped leaf-like organs can be duplicated by the application of exogenous NPA and cytokinin to wild-type tobacco seedlings.We have also observed adventitious leaf-like organs with altered petiole and blade morphology in the transgenic plants treated with auxin transport inhibitors.These results suggest that the combination of diminished auxin transport and elevated cytokinin can lead to alterations in leaf development in tobacco.