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Title: Plant cytokinesis and the construction of new cell wall

Cytokinesis in plants is fundamentally different from that in animals and fungi. In plant cells, a cell plate forms through the fusion of cytokinetic vesicles and then develops into the new cell wall, partitioning the cytoplasm of the dividing cell. The formation of the cell plate entails multiple stages that involve highly orchestrated vesicle accumulation, fusion and membrane maturation, which occur concurrently with the timely deposition of polysaccharides such as callose, cellulose and cross‐linking glycans. This review summarizes the major stages in cytokinesis, endomembrane components involved in cell plate assembly and its transition to a new cell wall. An animation that can be widely used for educational purposes further summarizes the process.

 
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Award ID(s):
1818219
NSF-PAR ID:
10371355
Author(s) / Creator(s):
 ;  ;  ;  ;  ;  ;  
Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
FEBS Letters
Volume:
596
Issue:
17
ISSN:
0014-5793
Page Range / eLocation ID:
p. 2243-2255
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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  1. Abstract Plant cytokinesis, a fundamental process of plant life, involves de novo formation of a “cell plate” partitioning the cytoplasm of dividing cells. Cell plate formation is directed by orchestrated delivery, fusion of cytokinetic vesicles, and membrane maturation to form a nascent cell wall by timely deposition of polysaccharides. During cell plate maturation, the fragile membrane network transitions to a fenestrated sheet and finally a young cell wall. Here, we approximated cell plate sub-structures with testable shapes and adopted the Helfrich-free energy model for membranes, including a stabilizing and spreading force, to understand the transition from a vesicular network to a fenestrated sheet and mature cell plate. Regular cell plate development in the model was possible, with suitable bending modulus, for a two-dimensional late stage spreading force of 2–6 pN/nm, an osmotic pressure difference of 2–10 kPa, and spontaneous curvature between 0 and 0.04 nm−1. With these conditions, stable membrane conformation sizes and morphologies emerged in concordance with stages of cell plate development. To reach a mature cell plate, our model required the late-stage onset of a spreading/stabilizing force coupled with a concurrent loss of spontaneous curvature. Absence of a spreading/stabilizing force predicts failure of maturation. The proposed model provides a framework to interrogate different players in late cytokinesis and potentially other membrane networks that undergo such transitions. Callose, is a polysaccharide that accumulates transiently during cell plate maturation. Callose-related observations were consistent with the proposed model’s concept, suggesting that it is one of the factors involved in establishing the spreading force. 
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  2. null (Ed.)
    Cytokinesis in land plants involves the formation of a cell plate that develops into the new cell wall. Callose, a β-1,3 glucan accumulates at later stages of cell plate development presumably to stabilize this delicate membrane network during expansion. Cytokinetic callose is considered specific to multicellular plant species, as it has not been detected in unicellular algae. Here we present callose at the cytokinesis junction of the unicellular charophyte, P. margaritaceum. Callose deposition at the division plane of P. margaritaceum showed distinct, spatiotemporal patterns likely representing distinct roles of this polymer in cytokinesis. Pharmacological inhibition by Endosidin 7 resulted in cytokinesis defects, consistent with the essential role for this polymer in P. margaritaceum cell division. Cell wall deposition at the isthmus zone was also affected by the absence of callose, demonstrating the dynamic nature of new wall assembly in P. margaritaceum. The identification of candidate callose synthase genes provides molecular evidence for callose biosynthesis in P. margaritaceum. The evolutionary implications of cytokinetic callose in this unicellular Zygnematopycean alga is discussed in the context of the conquest of land by plants. 
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  3. Baskin, Tobias Isaac (Ed.)
    In plant cytokinesis, de novo formation of a cell plate evolving into the new cell wall partitions the cytoplasm of the dividing cell. In our earlier chemical genomics studies, we identified and characterized the small molecule endosidin-7, that specifically inhibits callose deposition at the cell plate, arresting late-stage cytokinesis in arabidopsis. Endosidin-7 has emerged as a very valuable tool for dissecting this essential plant process. To gain insights regarding its mode of action and the effects of cytokinesis inhibition on the overall plant response, we investigated the effect of endosidin-7 through a nuclear magnetic resonance spectroscopy (NMR) metabolomics approach. In this case study, metabolomics profiles of arabidopsis leaf and root tissues were analyzed at different growth stages and endosidin-7 exposure levels. The results show leaf and root-specific metabolic profile changes and the effects of endosidin-7 treatment on these metabolomes. Statistical analyses indicated that the effect of endosidin-7 treatment was more significant than the developmental impact. The endosidin-7 induced metabolic profiles suggest compensations for cytokinesis inhibition in central metabolism pathways. This study further shows that long-term treatment of endosidin-7 profoundly changes, likely via alteration of hormonal regulation, the primary metabolism of arabidopsis seedlings. Hormonal pathway-changes are likely reflecting the plant’s responses, compensating for the arrested cell division, which in turn are leading to global metabolite modulation. The presented NMR spectral data are made available through the Metabolomics Workbench, providing a reference resource for the scientific community. 
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  4. Introduction

    During proliferative plant cell division, the new cell wall, called the cell plate, is first built in the middle of the cell and then expands outward to complete cytokinesis. This dynamic process requires coordinated movement and arrangement of the cytoskeleton and organelles.

    Methods

    Here we use live-cell markers to track the dynamic reorganization of microtubules, nuclei, endoplasmic reticulum, and endomembrane compartments during division and the formation of the cell plate in maize leaf epidermal cells.

    Results

    The microtubule plus-end localized protein END BINDING1 (EB1) highlighted increasing microtubule dynamicity during mitosis to support rapid changes in microtubule structures. The localization of the cell-plate specific syntaxin KNOLLE, several RAB-GTPases, as well as two plasma membrane localized proteins was assessed after treatment with the cytokinesis-specific callose-deposition inhibitor Endosidin7 (ES7) and the microtubule-disrupting herbicide chlorpropham (CIPC). While ES7 caused cell plate defects inArabidopsis thaliana, it did not alter callose accumulation, or disrupt cell plate formation in maize. In contrast, CIPC treatment of maize epidermal cells occasionally produced irregular cell plates that split or fragmented, but did not otherwise disrupt the accumulation of cell-plate localized proteins.

    Discussion

    Together, these markers provide a robust suite of tools to examine subcellular trafficking and organellar organization during mitosis and cell plate formation in maize.

     
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  5. null (Ed.)
    Abstract Building a complex structure such as the cell wall, with many individual parts that need to be assembled correctly from distinct sources within the cell, is a well-orchestrated process. Additional complexity is required to mediate dynamic responses to environmental and developmental cues. Enzymes, sugars, and other cell wall components are constantly and actively transported to and from the plasma membrane during diffuse growth. Cell wall components are transported in vesicles on cytoskeletal tracks composed of microtubules and actin filaments. Many of these components, and additional proteins, vesicles, and lipids are trafficked to and from the cell plate during cytokinesis. In this review, we first discuss how the cytoskeleton is initially organized to add new cell wall material or to build a new cell wall, focusing on similarities during these processes. Next, we discuss how polysaccharides and enzymes that build the cell wall are trafficked to the correct location by motor proteins and through other interactions with the cytoskeleton. Finally, we discuss some of the special features of newly formed cell walls generated during cytokinesis. 
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