The effect of colchicine on microtubules and microfibrils in root hairs

Roots of Equisetum hyemale and Raphanus sativus were grown in concentrations of colchicine that slowed down root hair growth initially, and later stopped growth completely. The treatment effected depolymerization of most of the microtubules. The wall texture in root hairs of E. hyemale was helicoidal after treatment with colchicine, as in untreated hairs. In root hairs of R. sativus the deposition orientation of the microfibrils changed (prior to microtubule depolymerization) from axial to oblique and transverse, but deposition remained ordered. As ordered wall texture is deposited in orientations that differ from the orientation of the depolymerizing microtubules and also in the absence of microtubules, it is concluded that microtubules do not directly control the orientation of nascent microfibrils.