Plant Cell Monogr (9)
D.P.S. Verma and Z. Hong: Cell Division Control in Plants
DOI 10.1007/7089_2007_127/Published online: 1 August 2007
©Springer-Verlag Berlin Heidelberg 2007
Cytoskeletal Motor Proteins in Plant Cell Division
Yu h - Ru Ju l i e Le e · B o L i u ()
Section of Plant Biology, University of California, Davis, CA 95616, USA
[email protected]
AbstractPlant cell division involves anastral spindles with incompletely focused poles
and the phragmoplast with antiparallel microtubules. The organization of the spindle mi-
crotubule array and the phragmoplast array is thought to be dependent on microtubule-
based motor kinesins. Among the more than 50 kinesins encoded by a single plant
genome, a number of them are either proven or predicted to be essential for cell di-
vision. Members of the Kinesin-14 subfamily play a critical role in organizing spindle
poles. Some kinesins yet to be identified could be required for facilitating nuclear enve-
lope breakdown at the end of prophase, and others for mediating the interaction between
chromosomes and microtubules for spindleassembly. During anaphase, the disassembly
of kinetochore fibers and the accompanying sister chromatid movement would definitely
be assisted by kinesins. Similarly to fungi and animals, plants likely use Kinesin-5 for
microtubule sliding, leading to spindle elongation. During cytokinesis, Kinesin-12 is re-
quired for establishing the antiparallel fashion of the phragmoplast microtubule array.
Microtubule turnover in this highly dynamic array also depends on plant-specific ki-
nesins acting on an MAP kinase cascade. More than one kinesin is predicted to deliver
vesicles for cell plate assembly. Lastly, recent data also suggest that kinesins play a critical
role in spatial regulation of cytokinesis. Very little has been learned about the poten-
tial roles of myosins in plant cell division. Whether myosins are also involved in vesicle
transport in the phragmoplast awaits further examination. We can conclude that splendid
cytoskeletal motors play splendid roles in plant cell division.
1
Introduction
In flowering plants, mitosis and meiosis involve anastral spindles with incom-
pletely focused spindle poles. Following the segregation of genetic material,
cytokinesis is brought about by a unique apparatus known as the phrag-
moplast, which is an evolutionary landmark found among organisms from
advanced green algae to land plants (Graham et al. 2000). While plant mi-
tosis and meiosis share many features similar to those of animal cells, plant
cytokinesis emphasizes the buildup of the cell plate while fungal and animal
cytokinesis emphasizes the contraction of the actomyosin ring.
The anastral spindle apparatus has a microtubule array with the kineto-
chore fibers focused at more than one discrete point, implicating that plant
cells contain diffuse microtubule-organizing centers (MTOCs) during mi-
tosis and meiosis (Palevitz 1993). In different plant cell types, the spindle
microtubule array often exhibits flexible shapes largely due to the geomet-