Cytoskeletal Drugs and Gravity-Induced Lateral Auxin Transport in Rice Coleoptiles

Abstract: Gravity-induced events such as amyloplast sedimentation and lateral auxin transport were probed with cytoskeletal drugs in coleoptiles of rice ( Oryza sativa L.). Amyloplast sedimentation was retarded by taxol. Lateral transport of auxin (³H-indoleacetic acid) was strongly inhibited by EPC (ethyl N-phenylcarbamate), but only partially inhibited by taxol. 1 mM EPC reduced gravitropism while phototropism was not affected. The findings suggest that microtubules may transduce pressure or proximity of amyloplasts to the auxin exporter in the plasmalemma.