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Current Opinion in Plant Biology Jun 2018The long-distance transport of sugars and nutrients through the phloem is essential for the proper function and growth of vascular plants. However, in addition to... (Review)
Review
The long-distance transport of sugars and nutrients through the phloem is essential for the proper function and growth of vascular plants. However, in addition to essential nutrients and sugars, phloem sap also contains small molecules (e.g. hormones) as well as a diverse population of macromolecules (i.e. proteins small RNAs, and mRNAs), the endogenous functions of which remain largely unknown. Understanding the cellular origins of these mobile macromolecules, their path into and out of the phloem translocation stream, and their fate at their new destination is essential for characterizing their presumptive function. Specialized plasmodesmal connections that regulate phloem entry and exit are central to all of these processes. Here, we highlight new discoveries underscoring plasmodesmal structure and function during unloading of various molecules in the sink, and discuss how these findings shape a new view for the potential function of phloem-mobile macromolecules.
Topics: Biological Transport; Phloem; Plants; Plasmodesmata; RNA, Messenger; Signal Transduction
PubMed: 29751226
DOI: 10.1016/j.pbi.2018.04.014 -
Journal of Experimental Botany Mar 2023Plasmodesmata are cytosolic bridges, lined by the plasma membrane and traversed by endoplasmic reticulum; plasmodesmata connect cells and tissues, and are critical for...
Plasmodesmata are cytosolic bridges, lined by the plasma membrane and traversed by endoplasmic reticulum; plasmodesmata connect cells and tissues, and are critical for many aspects of plant biology. While plasmodesmata are notoriously difficult to extract, tissue fractionation and proteomic analyses can yield valuable knowledge of their composition. Here we have generated two novel proteomes to expand tissue and taxonomic representation of plasmodesmata: one from mature Arabidopsis leaves and one from the moss Physcomitrium patens, and leveraged these and existing data to perform a comparative analysis to identify evolutionarily conserved protein families that are associated with plasmodesmata. Thus, we identified β-1,3-glucanases, C2 lipid-binding proteins, and tetraspanins as core plasmodesmal components that probably serve as essential structural or functional components. Our approach has not only identified elements of a conserved plasmodesmal proteome, but also demonstrated the added power offered by comparative analysis for recalcitrant samples. Conserved plasmodesmal proteins establish a basis upon which ancient plasmodesmal function can be further investigated to determine the essential roles these structures play in multicellular organism physiology in the green lineages.
Topics: Plasmodesmata; Proteomics; Arabidopsis; Arabidopsis Proteins; Cell Membrane; Proteome
PubMed: 36639877
DOI: 10.1093/jxb/erad022 -
Methods in Cell Biology 2020Plasmodesmata are membrane-lined cytoplasmic passageways that facilitate the movement of nutrients and various types of molecules between cells in the plant. They are...
Plasmodesmata are membrane-lined cytoplasmic passageways that facilitate the movement of nutrients and various types of molecules between cells in the plant. They are highly dynamic channels, opening or closing in response to physiological and developmental stimuli or environmental challenges such as biotic and abiotic stresses. Accumulating evidence supports the idea that such dynamic controls occur through integrative cellular mechanisms. Currently, a few fluorescence-based methods are available that allow monitoring changes in molecular movement through plasmodesmata. In this chapter, following a brief introduction to those methods, we provide a detailed step-by-step protocol for the Drop-ANd-See (DANS) assay, which is advantageous when it is desirable to measure plasmodesmal permeability non-invasively, in situ and in real-time. We discuss the experimental conditions one should consider to produce reliable and reproducible DANS results along with troubleshooting ideas.
Topics: Arabidopsis; Biological Assay; Biological Transport; Coloring Agents; Cytological Techniques; Fluoresceins; Image Processing, Computer-Assisted; Plant Development; Plasmodesmata; Reproducibility of Results
PubMed: 32896335
DOI: 10.1016/bs.mcb.2020.04.008 -
Journal of Plant Physiology Feb 2021Plant tissues exhibit a symplasmic organization; the individual protoplasts are connected to their neighbors via cytoplasmic bridges that extend through pores in the... (Review)
Review
Plant tissues exhibit a symplasmic organization; the individual protoplasts are connected to their neighbors via cytoplasmic bridges that extend through pores in the cell walls. These bridges may have diameters of a micrometer or more, as in the sieve pores of the phloem, but in most cell types they are smaller. Historically, botanists referred to cytoplasmic bridges of all sizes as plasmodesmata. The meaning of the term began to shift when the transmission electron microscope (TEM) became the preferred tool for studying these structures. Today, a plasmodesma is widely understood to be a 'nano-scale' pore. Unfortunately, our understanding of these nanoscopic channels suffers from methodological limitations. This is exemplified by the fact that state-of-the-art EM techniques appear to reveal plasmodesmal pore structures that are much smaller than the tracer molecules known to diffuse through these pores. In general, transport processes in pores that have dimensions in the size range of the transported molecules are governed by different physical parameters than transport process in the macroscopic realm. This can lead to unexpected effects, as experience in nanofluidic technologies demonstrates. Our discussion of problems of size in plasmodesma research leads us to conclude that the field will benefit from technomimetic reasoning - the utilization of concepts developed in applied nanofluidics for the interpretation of biological systems.
Topics: Biological Transport; Phloem; Plasmodesmata; Terminology as Topic
PubMed: 33388666
DOI: 10.1016/j.jplph.2020.153341 -
Methods in Molecular Biology (Clifton,... 2022Plant plasmodesmata (PD) are complex intercellular channels consisting of a thin endoplasmic reticulum (ER) tubule enveloped by the plasma membrane (PM). PD were first...
Plant plasmodesmata (PD) are complex intercellular channels consisting of a thin endoplasmic reticulum (ER) tubule enveloped by the plasma membrane (PM). PD were first observed by electron microscopy about 50 years ago and, since, numerous studies in transmission and scanning electron microscopy have provided important information regarding their overall organization, revealing at the same time their diversity in terms of structure and morphology. However, and despite the fact that PD cell-cell communication is of critical importance for plant growth, development, cellular patterning, and response to biotic and abiotic stresses, linking their structural organization to their functional state has been proven difficult. This is in part due to their small size (20-50 nm in diameter) and the difficulty to resolve these structures in three dimensions at nanometer resolution to provide details of their internal organization.In this protocol, we provide in detail a complete process to produce high-resolution transmission electron tomograms of PD. We describe the preparation of the plant sample using high-pressure cryofixation and cryo-substitution. We also describe how to prepare filmed grids and how to cut and collect the sections using an ultramicrotome. We explain how to acquire a tilt series and how to reconstruct a tomogram from it using the IMOD software. We also give a few guidelines on segmentation of the reconstructed tomogram.
Topics: Electron Microscope Tomography; Microscopy, Electron, Scanning; Microtomy; Plant Cells; Plasmodesmata
PubMed: 35349132
DOI: 10.1007/978-1-0716-2132-5_3 -
International Journal of Molecular... May 2022Plasmodesmata (PD) are plant-specific channels connecting adjacent cells to mediate intercellular communication of molecules essential for plant development and defense.... (Review)
Review
Plasmodesmata (PD) are plant-specific channels connecting adjacent cells to mediate intercellular communication of molecules essential for plant development and defense. The typical PD are organized by the close apposition of the plasma membrane (PM), the desmotubule derived from the endoplasmic reticulum (ER), and spoke-like elements linking the two membranes. The plasmodesmal PM (PD-PM) is characterized by the formation of unique microdomains enriched with sphingolipids, sterols, and specific proteins, identified by lipidomics and proteomics. These components modulate PD to adapt to the dynamic changes of developmental processes and environmental stimuli. In this review, we focus on highlighting the functions of sphingolipid species in plasmodesmata, including membrane microdomain organization, architecture transformation, callose deposition and permeability control, and signaling regulation. We also briefly discuss the difference between sphingolipids and sterols, and we propose potential unresolved questions that are of help for further understanding the correspondence between plasmodesmal structure and function.
Topics: Cell Communication; Cell Membrane; Plasmodesmata; Sphingolipids; Sterols
PubMed: 35628487
DOI: 10.3390/ijms23105677 -
Current Opinion in Plant Biology Dec 2011Plasmodesmata are doors in the rigid cell wall. In multicellular tissues, they allow the passage of molecules needed to create physiological gradients and, by closure,... (Review)
Review
Plasmodesmata are doors in the rigid cell wall. In multicellular tissues, they allow the passage of molecules needed to create physiological gradients and, by closure, symplastic boundaries, which are necessary for the fundamental processes of plant growth, development and defence. Despite this central role in plant growth our knowledge of their contribution has been hindered by difficulties in biochemical and molecular characterisation. Recent advances in proteomic, biochemical, cell biological and genetic analysis of their structure and function is showing that plasmodesmata are plastic yet highly regulated structures. They require the perception of small molecule signals (such as reactive oxygen species) to activate local changes in the cell wall that place physical constraints on the channel. This article reviews recent evidence that highlights the roles of the membrane subcomponents both as structural elements and as environments for resident signalling molecules.
Topics: Biological Transport; Plasmodesmata; Signal Transduction
PubMed: 21820942
DOI: 10.1016/j.pbi.2011.07.007 -
Trends in Plant Science Aug 2021Successful plant organ development depends on well-coordinated intercellular communication between the cells of the organ itself, as well as with surrounding cells.... (Review)
Review
Successful plant organ development depends on well-coordinated intercellular communication between the cells of the organ itself, as well as with surrounding cells. Intercellular signals often move via the symplasmic pathway using plasmodesmata. Intriguingly, brief periods of symplasmic isolation may also be necessary to promote organ differentiation and functionality. Recent findings suggest that symplasmic isolation of a subset of parental root cells and newly forming lateral root primordia (LRPs) plays a vital role in modulating lateral root development and emergence. In this opinion article we discuss how two symplasmic domains may be simultaneously established within an LRP and its overlying cells, and the significance of plasmodesmata in this process.
Topics: Arabidopsis; Cell Differentiation; Plant Roots; Plasmodesmata
PubMed: 33685810
DOI: 10.1016/j.tplants.2021.01.006 -
PloS One Apr 2011The multicellular nature of plants requires that cells should communicate in order to coordinate essential functions. This is achieved in part by molecular flux through...
The multicellular nature of plants requires that cells should communicate in order to coordinate essential functions. This is achieved in part by molecular flux through pores in the cell wall, called plasmodesmata. We describe the proteomic analysis of plasmodesmata purified from the walls of Arabidopsis suspension cells. Isolated plasmodesmata were seen as membrane-rich structures largely devoid of immunoreactive markers for the plasma membrane, endoplasmic reticulum and cytoplasmic components. Using nano-liquid chromatography and an Orbitrap ion-trap tandem mass spectrometer, 1341 proteins were identified. We refer to this list as the plasmodesmata- or PD-proteome. Relative to other cell wall proteomes, the PD-proteome is depleted in wall proteins and enriched for membrane proteins, but still has a significant number (35%) of putative cytoplasmic contaminants, probably reflecting the sensitivity of the proteomic detection system. To validate the PD-proteome we searched for known plasmodesmal proteins and used molecular and cell biological techniques to identify novel putative plasmodesmal proteins from a small subset of candidates. The PD-proteome contained known plasmodesmal proteins and some inferred plasmodesmal proteins, based upon sequence or functional homology with examples identified in different plant systems. Many of these had a membrane association reflecting the membranous nature of isolated structures. Exploiting this connection we analysed a sample of the abundant receptor-like class of membrane proteins and a small random selection of other membrane proteins for their ability to target plasmodesmata as fluorescently-tagged fusion proteins. From 15 candidates we identified three receptor-like kinases, a tetraspanin and a protein of unknown function as novel potential plasmodesmal proteins. Together with published work, these data suggest that the membranous elements in plasmodesmata may be rich in receptor-like functions, and they validate the content of the PD-proteome as a valuable resource for the further uncovering of the structure and function of plasmodesmata as key components in cell-to-cell communication in plants.
Topics: Arabidopsis; Arabidopsis Proteins; Blotting, Western; Chromatography, Liquid; Plasmodesmata; Proteome
PubMed: 21533090
DOI: 10.1371/journal.pone.0018880 -
Current Opinion in Plant Biology Feb 2016Communication between cells is a crucial step to coordinate organ formation and tissue patterning. In plants, the intercellular transport of metabolites and signalling... (Review)
Review
Communication between cells is a crucial step to coordinate organ formation and tissue patterning. In plants, the intercellular transport of metabolites and signalling molecules occur symplastically through membranous structures (named plasmodesmata) that traverse the cell wall to connect the cytoplasm and endoplasmic reticulum of neighbouring cells. This review aims to highlight the importance of symplastic communication in plant development. We revisit current literature reporting the effects of changing plasmodesmata in cell morphogenesis, organ initiation and meristem maintenance and comment on recent work involving the identification of novel plasmodesmata regulators and of mobile developmental proteins and RNA molecules. New opportunities for unravelling the dynamic regulation and function of plasmodesmata are also discussed.
Topics: Biological Transport; Plant Development; Plasmodesmata; Signal Transduction
PubMed: 26658335
DOI: 10.1016/j.pbi.2015.10.007