Microtubule reorganization during the cell cycle in synchronized BY‐2 tobacco suspensions

Abstract

Tobacco BY-2 suspension cultures were synchronized with aphidicolin in order to assess the relationship between microtubules (MTs), microfilaments (MFs), and the nuclear envelope (NE) at different stages of the cell cycle. Using immunofluorescence techniques, ordered MT arrays were found in the cortex in G,; few MTs are evident deeper in the cytoplasm or near the nucleus. However, MTs radiate from the surface of the nucleus during S and G, as the interphase cortical array is replaced by the preprophase band. Pennuclear fluorescence is also visible at the end of cytokinesis but does not overlap with new ordered cortical arrays early in G,. When isolated nuclei are examined, associated MTs are again evident in S and G,, but not in G,. Microfilaments are colocalized with the MTs in the radiating arrays, as ascertained by dual staining of cells with rhodamine phalloidin. Propyzamide treatment leads to the loss of MTs at all stages, while cytoplasmic and perinuclear MF networks persist. Conversely, cytochalasin D disrupts MFs, including those radiating from the nucleus durmg S and G2, without any apparent effect on MTs. The results cast doubt on a proposed role for the NE in the generation of cortical MTs in plants. A universal role for MFs in the deployment of MTs is also in question.

A Katanin-like Protein Regulates Normal Cell Wall gBiosynthesis and Cell Elongation

“…However, the mutation appears not to affect the organization of microtubule arrays when cells are undergoing mitosis and cytokinesis. During late stages of cytokinesis in somatic plant cells, a perinuclear microtubule array can be detected transiently (Hasezawa et al, 1991). When cells exit from cytokinesis, perinuclear microtubule array rapidly depolymerizes while cortical microtubule array arises, and two arrays do not overlap (Hasezawa et al, 1991).…”

The Microtubule Plus-End Binding Protein EB1 Functions in Root Responses to Touch and Gravity Signals in Arabidopsis

“…Perinuclear and cytoplasmic microtubules were also visible in these cells. Although the significance of nuclear-associated EB1 is not clear, a transient perinuclear array of microtubules (the radial array) has been detected in plant cells that are exiting cytokinesis (Hasezawa et al, 1991), and it is possible that EB1 proteins are associated with these microtubules. Nuclear labeling of GFP-tagged EB1a has also been reported in cytokinetic Arabidopsis suspension cells (Chan et al, 2003(Chan et al, , 2005.…”

Interphase and preprophase microtubule organization in some polarized cell types of the liverwort Marchantia paleacea Bert.

“…This microtubule array seems to behave later as a PPB (see also Galatis et al, 1986;Sawidis et al, 1991). It should be noted here that PPBs in some angiosperm cells appear at late S or G2 stage (Gunning & Wick, 1985;Mineyuki, Wick & Gunning, 1988;Gunning &Sammut, 1990;Hasezawa, Marc &Palevitz, 1991).…”