Cell Cycle-Dependent Targeting of a Kinesin at the Plasma Membrane Demarcates the Division Site in Plant Cells

Abstract

Eukaryotic cells have developed different mechanisms to establish the division plane. In plants, the position is determined before the onset of mitosis by the preprophase band (PPB). This ring of microtubules surrounds the nucleus and disappears completely by prometaphase. An unknown marker is left behind by the PPB, providing the necessary spatial cues during cytokinesis. At the position of the PPB, cortical actin is removed or modified to generate an actin-depleted zone that was proposed to provide the structural means for phragmoplast guidance. Here, we identify a plasma membrane domain that emerges at the onset of mitosis and persists until the end of cytokinesis. The narrow band in the plasma membrane corresponds to the position of the PPB and is prevented from accumulation of a GFP-tagged kinesin GFP-KCA1; hence, it is called the KCA-depleted zone (KDZ). The KDZ demarcates the cortical division site independent from the mitotic cytoskeleton. Cell divisions in the absence of a KDZ resulted in misplaced cell plates, suggesting that the PPB transmits a signal to the plasma membrane required for correct cell plate guidance and vesicular targeting to the cortical division site.