Division Plane Orientation in Plant Cells

Abstract

This review discusses current knowledge on division plane determination in plant cells and how divisionwithin this plane is executed during cytokinesis. Plants cells are unusual among eukaryotes in that theirplanes of division are established prior to the onset of mitosis. Factors that contribute to the initialselection of the division plane include extra-cellular signals, cell geometry and polarity, and nuclearposition. During the G2 phase of the cell cycle, the formation of the preprophase band (PPB), a corticalassembly of microtubules and microfilaments, signals the future location of the division plane. Factorsimportant for PPB formation and maturation include the actin cytoskeleton, changes in microtubule dynamics,and protein dephosphorylation. Prior to its disassembly at prometaphase, the PPB functions in more thanone way to determine subsequent placement of the new cell wall. First, the PPB influences the initial orientationof the spindle, which facilitates subsequent cell wall formation within the division plane. Second, thePPB is thought to direct the formation of a cortical division site that persists after PPB breakdownand interacts during cytokinesis with the expanding phragmoplast, a cytoskeletal assembly that directsthe deposition of the partitioning cell wall. Both negative and positive cortical markers are implicatedin maintaining the memory of the former PPB site throughout mitosis and cytokinesis.KeywordsCell PlateDivision PlaneDivision SitePreprophase BandCell Plate FormationThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.