THE EFFECT OF TAXOL ON TRITICUM PREPROPHASE ROOT-CELLS - PREPROPHASE MICROTUBULE BAND ORGANIZATION SEEMS TO DEPEND ON NEW MICROTUBULE ASSEMBLY

To examine whether preprophase microtubule band (PPB) organization occ urs by rearrangement of pre-existing, or by assembly of new microtubul es (Mts), we treated root cells of Triticum turgidum with taxol, which stabilizes pre-existing Mts by slowing their depolymerization. With t axol early preprophase cells failed to form a normal PPB and PPB narro wing was prevented in cells that had already formed a wide one. The PP B became persistent in prometaphase cells and the formation of multipo lar prophase-prometaphase spindles was induced. These data favour the suggestion that PPB formation and narrowing, as well as prophase spind le development, are dynamic processes depending on continuous Mt assem bly at the PPB site and in the perinuclear cytoplasm.