EXPERIMENTAL MANIPULATION OF GAMMA-TUBULIN DISTRIBUTION IN ARABIDOPSIS USING ANTI-MICROTUBULE DRUGS

gamma-Tubulin-specific antibodies stain the microtubule (Mt) arrays of Arabidopsis suspension cells in a punctate or patchy manner. During d ivision, staining of kinetochore fibers and the phragmoplast is extens ive, except in the vicinity of the plus ends at the metaphase plate an d cell plate. gamma-Tubulin localization responds to low levels of col chicine, with staining receding farther toward the minus (pole) ends o f kinetochore fibers. At higher drug concentrations, gamma-tubulin als o associates with abnormal Mt foci as well as with the surface of the daughter nuclei facing the phragmoplast. During UV-induced recovery fr om colchicine, gamma-tubulin increases along the presumptive minus end s of mitotic Mts as well as the phragmoplast near the daughter nuclei. With CIPC, immunostaining is concentrated around the centers of focal Mt arrays in multipolar spindles. In the presence of taxol, Mts are m ore prominent but the mitotic apparatus and phragmoplast are abnormal. As with CIPC, gamma-tubulin is concentrated at focal arrays. Increase d punctate staining is also present in interphase arrays, with fluores cent dots often located at the ends of Mts. These results support a pr eferential association between gamma-tubulin and Mt minus ends, but ar e also consistent with more general binding along the walls of Mts. Th us, minus ends (and Mt nucleation sites) may be present throughout pla nt Mt arrays, but gamma-tubulin may also serve another function, such as in structural stabilization. (C) 1995 Wiley-Liss, Inc.