CHANGES IN MICROTUBULE ARRAYS DURING THE DIFFERENTIATION OF CORTICAL ROOT-CELLS OF RAPHANUS SATIVUS

Abstract

Cortical microtubule arrays in meristematic and differentiated cortical cells from root tips of R. sativus were studied using both immunofluorescence and dry cleaving. Length, density and orientation of the cortical microtubules were measured. Between individual, non-dividing cells of the meristematic zone the mean microtubule length varied from 0.9-1.3 .mu.m and the density varied from 1.7-3.2 .mu.m microtubule/.mu.2 membrane. The direction of the cortical tubules, running parallel to each other in individual cells, appeared to be more or less perpendicular to the root axis, at angles of 85-95.degree.. In elongated cortical cells, the mean length had increased to values between 2.6 and 6.7 .mu.m, while the density had decreased to 0.9-1.9 .mu.m/.mu.m2. Microtubules remained parallel to each other within 1 cell, although their angle with the root axis changed to highly variable values: between 10-80.degree.. Important changes apparently occur in the cytoskeleton during the differentiation of cortical cells. These changes might be related directly to the morphogenesis of these cells.