Endocytosis of Cell Surface Material Mediates Cell Plate Formation during Plant Cytokinesis

Abstract

Dividing plant cells perform a remarkable task of building a new cell wall within the cytoplasm in a few minutes. A long-standing paradigm claims that this primordial cell wall, known as the cell plate, is generated by delivery of newly synthesized material from Golgi apparatus-originated secretory vesicles. Here, we show that, in diverse plant species, cell surface material, including plasma membrane proteins, cell wall components, and exogenously applied endocytic tracers, is rapidly delivered to the forming cell plate. Importantly, this occurs even when de novo protein synthesis is blocked. In addition, cytokinesis-specific syntaxin KNOLLE as well as plasma membrane (PM) resident proteins localize to endosomes that fuse to initiate the cell plate. The rate of endocytosis is strongly enhanced during cell plate formation, and its genetic or pharmacological inhibition leads to cytokinesis defects. Our results reveal that endocytic delivery of cell surface material significantly contributes to cell plate formation during plant cytokinesis.

Evidence for a sorting endosome in Arabidopsis root cells

“…In contrast, BFA, which has been extensively used in protein trafficking studies in Arabidopsis root cells (Abas et al, 2006;Dettmer et al, 2006;Dhonukshe et al, 2006;Geldner et al, 2001Geldner et al, , 2003Grebe et al, 2003;Jaillais et al, 2006;Paciorek et al, 2005;Russinova et al, 2004), has a much broader effect on endomembrane compartments, as the TGN, GNOM endosomes, AtSNX1 endosomes/PVC/MVB and Golgi apparatus accumulate in or around the BFA compartments in Arabidopsis root cells (this work and Jaillais et al, 2006; for example). BFA is known to block recycling of PM proteins (Abas et al, 2006;Dettmer et al, 2006;Dhonukshe et al, 2006;Geldner et al, 2001Geldner et al, , 2003Grebe et al, 2003;Jaillais et al, 2006;Paciorek et al, 2005;Russinova et al, 2004). Here, we show that BFA is also capable of preventing the transfer of aleurain-GFP from the BFA compartment to the lytic vacuoles (see Figure 5), suggesting that BFA might have a general inhibitory effect on the transport of proteins from the PVC/MVB to the lytic vacuoles.…”

“…It is reasonable to consider that the behaviour of fluorescent proteins reflects the genuine location and dynamics of endogenous proteins, although we cannot exclude the possibility that the fluorescent-tagged proteins might have altered location or stability. We decided to use Arabidopsis root tips as a model system for our analysis, because endocytosis has been extensively studied in this tissue (Abas et al, 2006;Dettmer et al, 2006;Dhonukshe et al, 2006;Geldner et al, 2001Geldner et al, , 2003Grebe et al, 2003;Jaillais et al, 2006;Paciorek et al, 2005;Russinova et al, 2004). To compare the location of YFP-BP80-labelled organelles with compartments of the endocytic pathways, we used the fluorescent dye FM4-64 as an endocytic tracer (Dettmer et al, 2006;Geldner et al, 2003;Grebe et al, 2003;Jaillais et al, 2006;Paciorek et al, 2005).…”

“…The contradiction regarding the localization of RABF1 and RABF2b, which is probably due to the various model systems employed, precludes the use of these proteins as specific markers to distinguish between early and late endosomes/PVC. However, both proteins have been used in several studies as general endosomal markers (Dettmer et al, 2006;Dhonukshe et al, 2006;Geldner et al, 2003;Grebe et al, 2003;Jaillais et al, 2006;Takano et al, 2005). Recently, we demonstrated the existence of at least two distinct endosomal compartments in Arabidopsis root cells, depending on the presence of either the GNOM or AtSNX1 protein (Jaillais et al, 2006).…”

Membrane fusion process and assembly of cell wall during cytokinesis in the brown alga, Silvetia babingtonii (Fucales, Phaeophyceae)

“…However, there were differences in the membrane resource that produced the septum. In land plants, cell plate formation proceeded mainly by fusion of GVs, resulting in loading of the cell wall materials (Samuels et al 1995), although a recent study showed recruitment of vesicles from endocytosis into the cell plate (Dhonukshe et al 2006). Also, involvement of ER in the formation of the cell plate has been described.…”

The Plant Defense Elicitor Cryptogein Stimulates Clathrin-Mediated Endocytosis Correlated with Reactive Oxygen Species Production in Bright Yellow-2 Tobacco Cells

“…The observed 10% decrease in fluorescence could be explained by light stress bleaching the dye during sampling or its instability at room temperature (Bolte et al, 2004). It should be noted that emerging cell plates of dividing cells, previously described for their intense FM4-64 fluorescence (Bolte et al, 2004;Dhonukshe et al, 2006), were not affected by elicitor treatment (Fig. 1A, right).…”