Specific Inhibition of Polar Auxin Transport by n-Octanol in Maize Coleoptiles

옥수수(Zea mays L.) 자엽초 조직 절편에서 n-Octanol에 의한 옥신 극성 이동 억제

Both polar and gravity-induced lateral transport of auxin was markedly reduced in corn coleoptile segments by octanol treatment. Octanol enhance net auxin uptake without affecting that of benzoic acid, suggesting that the effect did not result from a nonspecific action on general membrane permeability. Since naphthylphthalamic acid (NPA) action on both transport and net uptake of auxin was substantially decreased in the presence of octanol, a specific interaction of octanol with the NPA site (efflux carrier) can be postulated. Studies on in vitro binding of NPA to membrane vesicles indicated that octanol did not interfere with NPA binding. When basipetal transport of auxin was impared by plasmolysis, octanol still inhibited auxin transport in the plasmolyzed tissues. The results ruled out the possibility of octanol acting at the plasmodesmata. Kinetic analysis of growth indicated that IAA-sustained growth was rapidly blocked by octanol implicating a common system by which auxin transport is linked to auxin action. Possible mechanisms for octanol action will be discussed.