Alteration of Microtubule Dynamic Instability during Preprophase Band Formation Revealed by Yellow Fluorescent Protein–CLIP170 Microtubule Plus-End Labeling[W]

Abstract

At the onset of mitosis, plant cells form a microtubular preprophase band that defines the plane of cell division, but the mechanism of its formation remains a mystery. Here, we describe the use of mammalian yellow fluorescent protein-tagged CLIP170 to visualize the dynamic plus ends of plant microtubules in transfected cowpea protoplasts and in stably transformed and dividing tobacco Bright Yellow 2 cells. Using plus-end labeling, we observed dynamic instability in different microtubular conformations in live plant cells. The interphase plant microtubules grow at 5 m/min, shrink at 20 m/min, and display catastrophe and rescue frequencies of 0.02 and 0.08 events/s, respectively, exhibiting faster turnover than their mammalian counterparts. Strikingly, during preprophase band formation, the growth rate and catastrophe frequency of plant microtubules double, whereas the shrinkage rate and rescue frequency remain unchanged, making microtubules shorter and more dynamic. Using these novel insights and four-dimensional time-lapse imaging data, we propose a model that can explain the mechanism by which changes in microtubule dynamic instability drive the dramatic rearrangements of microtubules during preprophase band and spindle formation in plant cells.

Universal rule for the symmetric division of plant cells

“…First, a dynamic cytoskeleton is critical to allow the population of microtubules to explore many configurations. Therefore, the magnitude of β may reflect the activity of microtubule-associated proteins and kinases that take part in regulating microtubule dynamics (28). Interestingly, the cytoskeletal reorganization seen during preprophase was indeed shown to be supported by a dramatic increase in the dynamic instability of microtubules both on the cell cortex and in the cytoplasm (28,29).…”

“…Therefore, the magnitude of β may reflect the activity of microtubule-associated proteins and kinases that take part in regulating microtubule dynamics (28). Interestingly, the cytoskeletal reorganization seen during preprophase was indeed shown to be supported by a dramatic increase in the dynamic instability of microtubules both on the cell cortex and in the cytoplasm (28,29). Another possible factor is the size of the tubulin pool that may affect the strength of the bias favoring short endoplasmic microtubules.…”

Microtubule Dynamics in Living Root Hairs: Transient Slowing by Lipochitin Oligosaccharide Nodulation Signals

“…Their dynamics consist mainly of stochastic phases of polymerization and disassembly, a pattern of behavior known as dynamic instability (Mitchison and Kirschner, 1984), which can be defined in terms of growth, disassembly, the transition from growth to disassembly (catastrophe), and the transition from disassembly to growth (rescue; Hush et al, 1994;Dhonukshe and Gadella, 2003;Vos et al, 2003a). By changes in these dynamic instability parameters, cells rearrange the microtubular network and quickly respond to environmental and developmental stimuli (Desai and Mitchison, 1997).…”

Update: Plant Cortical Microtubule Arrays

“…Phospholipase D (PLD) was found to bind microtubules and membranes in vivo, and PLD remained bound to the plasma membrane when microtubules were depolymerized with a calcium and cold treatment combination (Gardiner et al, 2001). Furthermore, treatment with an activator of PLD, n-butanol, released microtubules from the plasma membrane of tobacco (Nicotiana tabacum) BY-2 cells, suggesting a role for PLD in microtubule-plasma membrane attachment (Dhonukshe and Gadella, 2003). However, conflicting results were obtained in a later study, which found that cortical microtubule remained attached to the plasma membrane of tobacco BY-2 protoplasts after treatment with n-butanol (Hirase et al, 2006).…”