Dynamics of microfilaments are similar, but distinct from microtubules during cytokinesis in living, dividing plant cells

Abstract

The development and dynamics of the phragmoplast cytoskeleton have been analyzed in living stamen hair cells of Tradescanria. Microtubules and actin microfilaments have been identified by microinjecting either carboxyfluorescein labeled brain tubulin or rhodamine phalloidin. Examination with the confocal laser scanning microscope has permitted sequential imaging of the fluorescent cytoskeletal elements in single living cells progressing through division. Phragmoplast microtubules initially emerge through the lateral coalescence of preexisting interzone microtubules. As cytokinesis progresses, these tightly clustered microtubules shorten in length and expand centrifugally toward the cell periphery. By contrast, the phragmoplast microfilaments appear to arise de novo in late anaphase in close association with the proximal surfaces of the reconstituting daughter nuclei. The microfilaments are oriented parallel to the microtubules but conspicuously do not occupy the equatorial region where microtubules interdigitate and where the cell plate vesicles aggregate and fuse. As development proceeds the microfilaments shorten in length and expand in girth, similar to microtubules, although they remain excluded from the cell plate region. In terminal phases of cell plate formation, microtubules degrade first in the central regions of the phragmoplast and later toward the edges, whereas microfilaments break down more uniformly throughout the phragmoplast. 0 1993 Wiley-Liss, Inc.

Vesicle Trafficking during Somatic Cytokinesis

“…This depends on targeted secretion to generate a new plasma membrane (PM; Whaley and Mollenhauer, 1963;Samuels et al, 1995;Jurgens, 2005aJurgens, , 2005b. Plant cells control cytokinesis by constructing a plant-specific cytoskeletal configuration, the phragmoplast (Zhang et al, 1993;Granger and Cyr, 2000;Assaad, 2001). The phragmoplast consists of a double array of parallel-oriented microtubules, actin filaments, associated molecules, and a cell plate assembly matrix acting as a framework to transport cell plate-building vesicles to the cell equator (Lambert, 1993;Staehelin and Hepler, 1996;Otegui et al, 2001;Wasteneys, 2002;SeguiSimarro et al, 2004).…”

Purification, Characterization, and cDNA Cloning of Profilin from Phaseolus vulgaris

“…The infection threads have been compared with the phragmosome formation in wounded tissue (Goodbody and Lloyd, 1990). The cytoskeleton seems to play a pivotal role in the development of this cellular structure (Clayton and Lloyd, 1985;Kakimoto and Shibaoka, 1987;Zhang et al, 1993). Our ultimate aim is to understand how the cytoskeleton participates in the symbiotic phenomenon between Rhizobium and the legumes; therefore, it is important to characterize, in detail, the cytoskeletal components and their role in this symbiotic interaction.…”

Synthetic Lipid (DOPG) Vesicles Accumulate in the Cell Plate Region But Do Not Fuse

“…The breakdown of actin filaments in the phragmoplast occurs uniformly along the whole width at the moment when the cell wall is completed, rather than in a centrifugal pattern (Cleary et al, 1992;Hepler et al, 1993;Zhang et al, 1993). A similar mechanism has been proposed for keeping exocytotic vesicles close to the growing tip of tip-growing cells, where actin filaments deliver vesicles to the vesicle-rich region in the pollen tube (Geitmann et al, 2000) and root hair tips (Miller et al, 1999) and keeps them in the tip (Ketelaar et al, 2003).…”

“…Other organelles, such as the Golgi bodies, mitochondria, and the vacuole stay outside the phragmoplast. The phragmoplast is initiated at late anaphase from the antiparallel overlapping microtubule and actin filament arrays at the spindle midzone, the plus-ends of cytoskeleton polymers facing the accumulating vesicles that form the cell plate (Kakimoto and Shibaoka, 1988;Baskin and Cande, 1990;Zhang et al, 1990Zhang et al, , 1993Wick, 1991;Cleary et al, 1992;Hepler et al, 1993;Sano et al, 2005). During expansion of the cell plate, microtubules disappear from the center of the phragmoplast as soon as a cell plate has formed (Zhang et al, 1990Cleary et al, 1992;Hepler et al, 1993;Granger and Cyr, 2000;Ueda et al, 2003), whereas actin filaments become shorter but remain present in the whole area throughout cell plate formation Zhang et al, 1993).…”