Article

Protoplasma

, Volume 226, Issue 3, pp 169-174

Narrowing of the preprophase microtubule band is not required for cell division plane determination in cultured plant cells

  • A. I. MarcusAffiliated withDepartment of Biology, Pennsylvania State University
  • , R. DixitAffiliated withDepartment of Biology, Pennsylvania State University
  • , R. J. CyrAffiliated withDepartment of Biology, Pennsylvania State UniversityIntercollege Graduate Program in Plant Physiology, Pennsylvania State University Email author 

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Summary.

In most higher-plant cells, cortical microtubules form a tightly focused preprophase band (PPB) that disappears with the onset of prometaphase, but whose location defines the future location of the cell plate at the end of cytokinesis. It is unclear whether the PPB microtubules themselves designate the precise area where the cell plate will insert, or rather if these microtubules are responding to a hierarchical signal(s). Here we show that narrowing of the microtubules within the PPB zone is not necessary for proper division plane determination. In cultured tobacco BY-2 cells in which PPB microtubules are depolymerized, the phragmoplast can still accurately locate and insert at the proper site. The data do not support a role for PPB microtubule narrowing in focusing the signal that is used later by the phragmoplast to position the cell plate; rather, proper phragmoplast positioning is more likely a consequence of a non-microtubule positional element. Although the PPB microtubules do not directly mark the division site, we show that they are required for accurate spindle positioning, an activity that presets the future growth trajectory of the phragmoplast and is necessary for insuring high-fidelity cell plate positioning.

Keywords: Cytokinesis; Mitosis; Microtubule; Cell division; Tobacco.