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Cell-cell communication in plants

Plants produce their nutrients through photosynthesis in the green leaves. Here, the energy of the sunlight is used to convert carbon dioxide (CO2) and water (H2O) into oxygen (O2) and sugars (Cn(H2O)n). But, how are these sugars distributed throughout the whole body of the plant? How do they reach other parts of the plant so that flowers, fruits or roots can metabolize them and grow? One way of transport is through plasmodesmata (PD). PD sit at the junctions between single plant cells. A number of cells together make up an organ, like the leaf, flower, root or stem.

During the evolution of multicellular organisms, all kingdoms developed unique cellular connections. While plants use PD to distribute nutrients and to communicate other signals, some fungi have septal pores and animals evolved gap junctions. If you want to find out more about PD and why they are special when compared to the analog cell-cell connections of fungi and animals, have a look at the further pages and our PD library. There is a lot to discover in the field of plasmodesmata.

Plasmodesmata library

M Miras, M Pottier, TM Schladt et al. (2022)
Plasmodesmata and their role in assimilate translocation
J Plant Physiol 270:153633. https://doi.org/10.1016/j.jplph.2022.153633

The authors review the current knowledge on photoassimilate transport across plasmodesmata as a prerequisite for translocation from leaves to recipient organs, in particular roots and developing seeds. They discuss the protein composition, structure, transport mechanism and regulation of PD with respect to carbohydrate allocation.

WS Peters, KH Jensen, HA Stone, M Knoblauch (2021)
Plasmodesmata and the problems with size: Interpreting the confusion
J Plant Physiol 257:153341. https://doi.org/10.1016/j.jplph.2020.153341

Today, a plasmodesma is widely understood to be a ‘nano-scale’ pore. The authors argue that this view may be based on methodological limitations and discuss how the utilization of concepts developed in applied nanofluidics could help solve the problems of size in plasmodesma research.

Z Anvarian, K Mykytyn, S Mukhopadhyay et al. (2019)
Cellular signalling by primary cilia in development, organ function and disease.
Nat Rev Nephrol 15:199–219. https://doi.org/10.1038/s41581-019-0116-9

Primary cilia serve as ‘signaling antennas’ between cells that regulate diverse cellular processes during development and maintain tissue homeostasis. The authors highlight central mechanisms by which primary cilia coordinate important signaling pathways and illustrate how defects in ciliary signalling are coupled to developmental disorders and disease progression.

RE Sager, JY Lee (2018)
Plasmodesmata at a glance
J Cell Sci 131 (11): jcs209346. https://doi.org/10.1242/jcs.209346

An overview of plasmodesmata form and function, with highlights on their development and variation, associated components and mobile factors. In addition, the authors present methodologies that are currently used to study plasmodesmata-mediated intercellular communication.

DK Song, JH Choi, MS Kim (2018)
Primary Cilia as a Signaling Platform for Control of Energy Metabolism
Diabetes Metab J 42(2):117-127. https://doi.org/10.4093/dmj.2018.42.2.117

Cilia are tiny hair-like organelles on the cell surface. Because they express many receptors, channels, and signaling molecules, primary cilia are considered as important signaling organelles. The authors summarize the current knowledge about cilia and cilia-associated signaling pathways in the regulation of body metabolism.

R Kooger, P Szwedziak, D Böck, M Pilhofer (2018)
CryoEM of bacterial secretion systems.
Curr Opin Struct Biol 52:64-70. https://doi.org/10.1016/j.sbi.2018.08.007

M Kitagawa, D Jackson (2017)
Plasmodesmata-Mediated Cell-to-Cell Communication in the Shoot Apical Meristem: How Stem Cells Talk
Plants 6(1): 12. https://doi.org/10.3390/plants6010012

Plasmodesmata (PD) interconnect most cells in the plant and generate a cytoplasmic continuum, to mediate short- and long-distance trafficking of various molecules. The authors summarize the recent knowledge of PD-mediated cell-to-cell communication in the shoot apical meristem, and discuss mechanisms underlying molecular trafficking through PD and its role in plant development.

F Bangs, KV Anderson (2017)
Primary Cilia and Mammalian Hedgehog Signaling
Cold Spring Harb Perspect Biol 1;9(5):a028175. https://doi.org/10.1101/cshperspect.a028175

The authors summarize the genetic and developmental studies used to deduce how Hedgehog (Hh) signal transduction is linked to cilia and the complex effects that perturbation of cilia structure can have on Hh signaling.

C Faulkner (2013)
Receptor-mediated signaling at plasmodesmata
Front. Plant Sci. 4(521):1-6. https://doi.org/10.3389/fpls.2013.00521

Proteomic data indicate that the plasmamembrane at plasmodesmata hosts many receptors and receptor kinases, as well as lipid raft and tetraspanin enriched microdomain associated proteins. The author discusses the hypothesis that the plasmamembrane at PD is specialized with respect to both composition and function.

F Abascal, R Zardoya (2013)
Evolutionary analyses of gap junction protein families
Biochimica et Biophysica Acta Biomembranes 1828(1):4-14. https://doi.org/10.1016/j.bbamem.2012.02.007

Gap junctions are intercellular channels that link the cytoplasm of neighboring cells in animals, enabling straight passage of ions and small molecules. Two different protein families, pannexins and connexins, form these channels. The authors discuss the phylogenies of these protein families.

Y Stahl, R Simon (2013)
Gated communities: apoplastic and symplastic signals converge at plasmodesmata to control cell fates
Journal of Experimental Botany 64(17):5237–41. https://doi.org/10.1093/jxb/ert245

This review focuses on developmental decisions that are coordinated by short- and long-distance communication of cells via plasmodesmata. The authors propose a model combining both apoplastic and symplastic signalling events via secreted ligands and their PD-localized receptor kinases which gate the symplastic transport of information molecules through PDs. Cell communities can thus coordinate cell-fate decisions non-cell autonomously by connecting or disconnecting symplastic subdomains.

TM Burch-Smith, S Stonebloom, M Xu, PC Zambryski (2011)
Plasmodesmata during development: re-examination of the importance of primary, secondary, and branched plasmodesmata structure versus function.
Protoplasma 248:61–74. https://doi.org/10.1007/s00709-010-0252-3

M Abedin, N King (2010)
Diverse evolutionary paths to cell adhesion
Trends Cell Biol. 20(12):734-742. https://doi.org/10.1016/j.tcb.2010.08.002

The morphological diversity of animals, fungi, plants, and other multicellular organisms stems from the fact that each lineage acquired multicellularity independently.  A prerequisite for each origin of multicellularity was the evolution of mechanisms for stable cell-cell adhesion or attachment. The authors argue that understanding the unicellular ancestry of cell adhesion helps illuminate the basic cell biology of multicellular development in modern organisms.

WJ Lucas, BK Ham, JY Kim (2009)
Plasmodesmata – bridging the gap between neighboring plant cells
Trends in Cell Biology 19(1):495-503. https://doi.org/10.1016/j.tcb.2009.07.003

Non-cell-autonomous proteins (NCAPs) are proteins that act beyond the cells in which their mRNA was transcribed and protein synthesized. They are involved in plant development and pathogen defense. The authors examine the role of plasmodesmata (PD) in the evolution of the NCAP movement pathway and evaluate mechanisms involved in the transport of these proteins to and through PD.

V Singla, JF Reiter (2006)
The Primary Cilium as the Cell's Antenna: Signaling at a Sensory Organelle
Science 313(5787):629-633. https://doi.org/10.1126/science.1124534

Almost every vertebrate cell has a specialized cell surface projection called a primary cilium. Although these structures were first described more than a century ago, the full scope of their functions remains poorly understood. The authors review emerging evidence that in addition to their well-established roles in sight, smell, and mechanosensation, primary cilia are key participants in intercellular signaling.

JA Raven (2005)
Evolution of Plasmodesmata
Annual Plant Reviews 18. https://doi.org/10.1002/9781119312994.apr0174

Comparative analyses of the occurence of plasmodesmata and analogous structures in higher plants and photosynthetic organisms combined with information from cladistic analysis of molecular biological and other data. Plasmodesmata evolved independently in several multicellular lineages likely to allow for efficient intercellular communication and transport.

W Lucas, JY Lee (2004)
Plasmodesmata as a supracellular control network in plants
Nat Rev Mol Cell Biol 5:712–726. https://doi.org/10.1038/nrm1470

The evolution of intercellular communication had an important role in the increasing complexity of both multicellular and supracellular organisms. Plasmodesmata, the intercellular organelles of the plant kingdom, establish an effective pathway for local and long-distance signalling.

AJE van Bel, M Knoblauch (2000)
Sieve element and companion cell: the story of the comatose patient and the hyperactive nurse
Australian Journal of Plant Physiology 27(6):477-487. https://doi.org/10.1071/PP99172

Sieve elements and companion cells constitute the modules of the conducting elements in the phloem of Angiosperms. The authors discuss the peculiarities of sieve elements – that have sacrificed all of their genetic and most of their metabolic equipment to serve photoassimilate translocation – and companion cells – that have gained metabolic weight during evolution.

WJ Lucas, RL Gilbertson (1994)
Plasmodesmata in relation to viral movement within leaf tissues
Annual Review of Phytopathology 32(1):387-415. https://doi.org/10.1146/annurev.py.32.090194.002131

Focus on the role of plasmodesmata in plant viral infection. Plasmodesmata in various tissues of the leaf and mechanisms of viral transport are discussed.

P Kirk, S Amsbury, L German et al. (2022)
A comparative meta-proteomic pipeline for the identification of plasmodesmata proteins and regulatory conditions in diverse plant species.
BMC Biology 20:128. https://doi.org/10.1186/s12915-022-01331-1

ML Brault, JD Petit, F Immel et al. (2019)
Multiple C2 domains and transmembrane region proteins (MCTPs) tether membranes at plasmodesmata
EMBO Reports 20:e47182. https://doi.org/10.15252/embr.201847182

Multiple C2 domain transmembrane region proteins (MCTP) are key regulators of intercellular signaling in plants. The authors show that they are localized at plasmodesmata where they bridge the organelles, endoplasmatic reticulum and plasmamembrane.

D Yan, SR Yadav, A Paterlini et al. (2019)
Sphingolipid biosynthesis modulates plasmodesmal ultrastructure and phloem unloading.
Nat. Plants 5:604–615. https://doi.org/10.1038/s41477-019-0429-5

The authors report a novel gene, PHLOEM UNLOADING MODULATOR (PLM). It encodes a putative enzyme required for the biosynthesis of sphingolipids with very-long-chain fatty acids. They establish a link between sphingolipid metabolism, the internal architecture of plasmodesmata with cytoplasmic sleeves and cell-to-cell connectivity.

K Ishikawa, K Tamura, Y Fukao, T Shimada (2019)
Structural and functional relationships between plasmodesmata and plant endoplasmic reticulum–plasma membrane contact sites consisting of three synaptotagmins
New Phytologist 226:798–808. https://doi.org/10.1111/nph.16391

Ishikawa et al. identified two additional components at endoplasmic reticulum (ER)-plasmamembrane contact sites (EPCS) in plant cells, that is Synaptotagmin 5 (SYT5) and SYT7. They interact with SYT1.  The authors suggest that EPCSs arranged around the PD squeeze the ER to regulate active transport via PD.

MS Grison, L Brocard, L Fouillen et al. (2015)
Specific membrane lipid composition is important for plasmodesmata function in Arabidopsis
Plant Cell 27(4):1228-50. https://doi.org/10.1105/tpc.114.135731

The work emphasizes the importance of lipids in defining plasmodesmata membranes. Modulation of the overall sterol composition of young dividing cells from A. thaliana reversibly impaired the PD localization of the glycosylphosphatidylinositolanchored proteins Plasmodesmata Callose Binding 1 and the b-1,3-glucanase PdBG2 and altered callose-mediated PD permeability.

MS Salmon, EMF Bayer (2012)
Dissecting plasmodesmata molecular composition by mass spectrometry-based proteomics
Front Plant Sci. 3:307. https://doi.org/10.3389%2Ffpls.2012.00307

The authors review the accomplishments and limitations of proteomic-based strategies to unravel the functional and structural complexity of plasmodesmata and discuss the role of the identified PD-associated proteins.

L Fernandez-Calvino, C Faulkner, J Walshaw et al. (2011)
Arabidopsis Plasmodesmal Proteome
PLoS ONE 6(4): e18880. https://doi.org/10.1371/journal.pone.0018880

The authors 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.

CL Thomas, EM Bayer, C Ritzenthaler et al. (2008)
Specific targeting of a plasmodesmal protein affecting cell-to-cell communication.
PLoS Biol 6(1): e7. https://doi.org/10.1371/journal.pbio.0060007

These studies identify a new family of plasmodesmata-located proteins (called PDLP1) that affect cell-to-cell communication. They exhibit a mode of intracellular trafficking and targeting novel for plant biology and provide technological opportunities for targeting different proteins to plasmodesmata to aid in plasmodesmal characterisation.

M Diao, S Huang (2021)
An Update on the Role of the Actin Cytoskeleton in Plasmodesmata: A Focus on Formins.
Front. Plant Sci. 12:647123. https://doi.org/10.3389/fpls.2021.647123

M Diao, S Ren, Q Wang et al. (2018)
Arabidopsis formin 2 regulates cell-to-cell trafficking by capping and stabilizing actin filaments at plasmodesmata.
eLife 7:e36316. https://doi.org/10.7554/eLife.36316

T Haraguchi, MTominaga, R Matsumoto et al. (2014)
Molecular Characterization and Subcellular Localization of Arabidopsis Class VIII Myosin, ATM1
The Journal of Biological Chemistry 289(18):12343–55. https://doi.org/10.1074/jbc.M113.521716

MJ Deeks,  JR Calcutt, EKS Ingle et al. (2012)
A Superfamily of Actin-Binding Proteins at the Actin-Membrane Nexus of Higher Plants.
Current Biology 22:1595–1600. http://dx.doi.org/10.1016/j.cub.2012.06.041

RG White, DA Barton (2011)
The cytoskeleton in plasmodesmata: a role in intercellular transport?
Journal of Experimental Botany 62(15):5249-66. https://doi.org/10.1093/jxb/err227

D Avisar, AI Prokhnevsky, VV Dolja (2008)
Class VIII Myosins Are Required for Plasmodesmatal Localization of a Closterovirus Hsp70 Homolog.
Journal of Virology 82(6):2836–43. https://doi.org/10.1128/JVI.02246-07

KM Wright, NT Wood, AG Roberts et al. (2007)
Targeting of TMV Movement Protein to Plasmodesmata Requires the Actin/ER Network: Evidence from FRAP.
Traffic 8:21–31. https://doi.org/10.1111/j.1600-0854.2006.00510.x

D Huang, Y Sun, Z Ma et al. (2019)
Salicylic acid-mediated plasmodesmal closure via Remorin-dependent lipid organization
Proc. Natl. Acad. Sci. U.S.A. 116 (42): 21274-21284. https://doi.org/10.1073/pnas.1911892116

This study unveils a molecular mechanism by which the key plant defense hormone salicylic acid (SA) triggers membrane lipid nanodomain reorganization, thereby regulating PD closure to impede virus spreading.

EE Deinum, BM Mulder, Y Benitez-Alfonso (2019)
From plasmodesma geometry to effective symplasmic permeability through biophysical modelling
eLife 8:e49000. https://doi.org/10.7554/eLife.49000

The authors developed new theoretical model to predict plasmodesmata transport capacity. In their calculations they are considering both the geometrical description of individual plasmodesmata and the molecular flow towards them.

MS Grison, P Kirk, ML Brault et al. (2019)
Plasma membrane-associated receptor-like kinases relocalize to plasmodesmata in response to osmotic stress
Plant Physiol 181(1): 142–160. doi: 10.1104/pp.19.00473

Plasmodesmata composition is not static, but changes e.g. in response to environmental stress. Qiān Shŏu kinase (QSK1) and inflorescence meristem kinase2 rapidly locate to PD under osmotic stress. QSK1 seems to be involved in callose-mediated regulation of plasmodesmata aperture.

M Kitagawa, T Tomoi, T Fukushima et al. (2019)
Abscisic Acid Acts as a Regulator of Molecular Trafficking through Plasmodesmata in the Moss Physcomitrella patens
Plant Cell Physiol 1;60(4):738-751. https://doi.org/10.1093/pcp/pcy249

Abscisic acid (ABA) plays a key role in various stress responses in the moss Physcomitrella patens. The authors report that ABA can rapidly and reversibly restrict molecular trafficking through PD and that this correlates with a reduction in PD pore size.

K Park, J Knoblauch, K Oparka et al. (2019)
Controlling intercellular flow through mechanosensitive plasmodesmata nanopores.
Nat Commun 10, 3564. https://doi.org/10.1038/s41467-019-11201-0


KJ Oparka, AG Roberts, P Boevink et al. (1999)
Simple, but not branched, plasmodesmata allow the nonspecific trafficking of proteins in developing tobacco leaves
Cell 11;97(6):743-54. https://doi.org/10.1016/S0092-8674(00)80786-2

Plant leaves undergo a sink–source transition during which a physiological change occurs from carbon import to export. During the sink–source transition, protein trafficking decreased substantially and was accompanied by a developmental switch from simple to branched forms of plasmodesmata. Contrary to dogma that plasmodesmata have a size exclusion limit below 1 kDa, the data demonstrate that nonspecific “macromolecular trafficking” is a general feature of simple plasmodesmata in sink leaves.

B Ding, MO Kwon, L Warnberg (1996)
Evidence that actin filaments are involved in controlling the permeability of plasmodesmata in tobacco mesophyll
The Plant Journal 10(1), 157-164. https://doi.org/10.1046/j.1365-313X.1996.10010157.x

The authors studied the role of actin filaments in regulating plasmodesmal transport by microinjection experiments in mesophyll cells of tobacco (Nicotiana tabacum L. cv. Samsun). When fluorescent dextrans of various molecular sizes were each co-injected with specific actin filament perturbants cytochalasin D (CD) or profilin into these cells, dextrans up to 20 kilodalton (kDa) moved from the injected cell into surrounding cells within 3–5 min. In contrast, when such dextrans were injected alone into the mesophyll cells, they remained in the injected cells.

KJ Oparka, DAM Prior (1992)
Direct evidence for pressure-generated closure of plasmodesmata
The Plant Journal 2(5):741 -750. https://doi.org/10.1111/j.1365-313X.1992.tb00143.x

The authors demonstrate through the use of microinjection procedures that symplastic transport is severely impeded when a pressure differential is generated between adjacent leaf trichome cells of Nicotiana clevelandii.

S Wolf, CM Deom, RN Beachy, WJ Lucas (1989)
Movement Protein of Tobacco Mosaic Virus Modifies Plasmodesmatal Size Exclusion Limit
Science 246(4928):377-379. DOI: 10.1126/science.246.4928.377

The first study showing that viral movement proteins modify the size exclusion limit of plasmodesmata.

M Kitagawa, P Wu, R Balkunde et al. (2022)
An RNA exosome subunit mediates cell-to-cell trafficking of a homeobox mRNA via plasmodesmata.
375(6577): 177-182. DOI: 10.1126/science.abm0840

Kitagawa et al. identify part of the machinery that manages cell-to-cell transport of mRNAs through plasmodesmata in plants. Transport of the mRNA encoding the KNOTTED1 homeobox transcription factor depends on Ribosomal RNA-Processing Protein 44 (AtRRP44A), which is a subunit of the RNA exosome.

W Horner, JO Brunkard (2021)
Cytokinins Stimulate Plasmodesmatal Transport in Leaves.
Front. Plant Sci. 12:674128. https://doi.org/10.3389/fpls.2021.674128

K Luo, N Huang, T Yu (2018)
Selective Targeting of Mobile mRNAs to Plasmodesmata for Cell-to-Cell Movement.
Plant Physiol 177(2):604-614. https://doi.org/10.1104%2Fpp.18.00107

TJ Ross-Elliott, KH Jensen, KS Haaning et al. (2017)
Phloem unloading in Arabidopsis roots is convective and regulated by the phloem-pole pericycle
eLife 6:e24125. https://doi.org/10.7554/eLife.24125

Phloem tubes form a network that transports sugar, proteins and other molecules around the plant to where they are needed. In the roots of Arabidopsis thaliana, these molecules move from the phloem directly into cells within a neighboring tissue called the phloem-pole pericycle. The authors report that this occurs via a unique class of pores, known as funnel plasmodesmata. Mathematical modelling suggests that sugars and other small molecules move freely through the funnel plasmodesmata, whereas large proteins pass through these pores in pulses (‘batch unloading’).

M Chen, G Tian, Y Gafni, V Citovsky (2005)
Effects of Calreticulin on Viral Cell-to-Cell Movement.
Plant Physiology 138:1866–76. https://doi.org/10.1104/pp.105.064386

F Kragler, J Monzer, K Shash et al. (1998)
Cell-to-cell transport of proteins: requirement for unfolding and characterization of binding to a putative plasmodesmal receptor
The Plant Journal 15(3):367–381. https://doi.org/10.1046/j.1365-313X.1998.00219.x

Through microinjection-based experiments, the authors show that cell-to-cell transport of the KNOTTED1 (KN1) protein likely requires a conformational change in plasmodesmata. The process my be analog to protein transport across the nuclear pore complex, involving a combination of protein unfolding and microchannel dilation.

WJ Lucas, S Bouché-Pillon, DP Jackson et al. (1995)
Selective trafficking of KNOTTED1 Homeodomain Protein and its mRNA through plasmodesmata
Science 270(5244):1980-83. https://doi.org/10.1126/science.270.5244.1980

Using microinjections the authors show that plasmodesmata facilitate the cell-to-cell transport of a plant-encoded transcription factor, KNOTTED1 (KN1). KN1 can also mediate the selective plasmodesmal trafficking of kn1 sense RNA. The study provides insight into some of the molecular events that orchestrate developmental processes in plants and identify one possible explanation for the plasticity of cell fate in the plant meristem.

W Nicolas, M Grison, S Trépout et al. (2017)
Architecture and permeability of post-cytokinesis plasmodesmata lacking cytoplasmic sleeves.
Nature Plants 3, 17082. https://doi.org/10.1038/nplants.2017.82

Using electron tomography and high pressure-freezing the authors resolved the 3D ultrastructure of near-native plasmodesmata. They propose a model where archetypal plasmodesmata (type II), harbouring a cytoplasmic sleeve and spoke elements, derive from the unconventional type I plasmodesmata established during cell plate formation.

J Fitzgibbon, K Bell, E King, K Oparka (2010)
Super-Resolution Imaging of Plasmodesmata Using Three-Dimensional Structured Illumination Microscopy
Plant Physiology 153(4):1453–1463. https://doi.org/10.1104/pp.110.157941

Using three-dimensional structured illumination microscopy (3D-SIM) the authors were able to obtain subdiffraction (“super-resolution”) images of plasmodesmata expressing a green fluorescent protein-tagged viral movement protein (MP) in tobacco (Nicotiana tabacum). 3D-SIM offers considerable potential in the subdiffraction imaging of plant cells, bridging an important gap between confocal and electron microscopy.

B Ding, R Turgeon, MV Parthasarathy (1992)
Substructure of freeze-substituted plasmodesmata
Protoplasma 169:28-41. https://doi.org/10.1007/BF01343367

This paper presents one of the earliest models of the substructure of Plasmodesmata in tobacco leaves. The authors used freeze substitution techniques in combination with high resolution electron microscopy and computer image enhancement.

A Kieninger, K Forchhammer, I Maldener (2019)
A nanopore array in the septal peptidoglycan hosts gated septal junctions for cell-cell communication in multicellular cyanobacteria.
International Journal of Medical Microbiology
309(8):151303. https://doi.org/10.1016/j.ijmm.2019.03.007

GL Weiss, A Kieninger, I Maldener et al. (2019)
Structure and Function of a Bacterial Gap Junction Analog.
Cell 178(2):374-384. https://doi.org/10.1016/j.cell.2019.05.055

I Kim, K Kobayashi, E Cho, PC Zambryski (2005)
Subdomains for transport via plasmodesmata corresponding to the apical–basal axis are established during Arabidopsis embryogenesis
Proc Natl Acad Sci USA 102(33):11945-50. https://doi.org/10.1073/pnas.0505622102

In Arabidopsis embryos, all cells are interconnected by plasmodesmata and integrated into a single symplast. As the embryo develops, the functional aperture of PD is down-regulated. The authors investigated the size limits of plasmodesmata for protein transport during embryogenesis by introducing symplasmic tracers in the shoot apical meristem and a subset of hypocotyl cells and monitoring their subsequent movement.

PT Tran, V Citovsky (2021)
Receptor-like kinase BAM1 facilitates early movement of the Tobacco mosaic virus
Commun Biol 4, 511. https://doi.org/10.1038/s42003-021-02041-0

Association of the receptor-like kinase BAM1 with the Tobacco mosaic virus movement protein at plasmodesmata (PD) facilitates the movement protein transport through PD, which, in turn, enhances the spread of the viral infection.

P Hunziker, SK Lambertz, K Weber et al. (2021)
Herbivore feeding preference corroborates optimal defense theory for specialized metabolites within plants.
Proc Natl Acad Sci USA 118. https://doi.org/10.1073/pnas.2111977118

Surprising effect of mutating glucosinolate transporters in Arabidopsis. Glucosinolates synthesized in the roots are not stored there and instead flushed to the vegetative parts where they eliminate the concentration gradient between young and low leaves (high vs low levels). This leads to alterations in feedint generalists.

Y Kazachkova, I Zemach, S Panda et al. (2021)
The GORKY glycoalkaloid transporter is indispensable for preventing tomato bitterness.
Native Plants 7: 468-480. https://doi.org/10.1038/s41477-021-00865-6

By mapping two inbred tomato populations the authors identify a 600 bp deletion in a single gene as the aunly causative locy for the investigated bitterness trait. The deletion resides in SlNPF1.5 which is shown to play a crucial role in releasing the bitter alpha/tomatine from vacuoles in ripening tomato fruits for conversion to esculeoside.

ZF Chao, YL Wang, YY Chen et al. (2021)
NPF transporters in synaptic-like vesicles control delivery of iron and copper to seeds.
Sci Adv 7: eabh2450. https://doi.org/10.1126/sciadv.abh2450

Family wide screen identifies NPF5.8 and 5.9 as first nicotianamine exporters in Arabidopsis. The genes have great potential in approaches aimed at biofortifying micronutrients in seeds. Moreover, the study provided an in intriguing mechanism for export through loading of small vesicles.

A Longo, NW Miles, R Dickstein (2018)
Genome mining of plant npfs reveals varying conservation of signature motifs associated with the mechanism of transport. 
Front Plant Sci 9: 1668 https://doi.org/10.1016/j.pbi.2022.102243
Bioinformatic analyses of the Nitrate and peptide transporter family (NPF) in a large variety of plant species revealing proportion of NPF members with and without Exxer/K motif and also absolute subclade sizes. Data can for example be mined for other subclades that are enlarged in specific plant species.

M Egevang Jørgensen, D Xu, C Crocoll et al. (2017)
Origin and evolution of transporter substrate specificity within the NPF family.
eLife 6: e19466. https://doi.org/10.7554/eLife.19466

On a quest to reveal the evolutionary origin of the distinct substrate specificity of GTR1/2 vs GTR3 the authors identified the first NPF transporters of cyanogenic glucosides. The transporter represents a potential breeding target for eliminating CG accumulation in cassava tubers.

RME Payne, D Xu, E Foureau et al. (2017)
An NPF transporter exports a central monoterpene indole alkaloid intermediate from the vacuole.
Native Plants
3: 16208. https://doi.org/10.1038/nplants.2016.208

Through co-expression analyses the authors identifies NPF2.9 in Catharanthus roseus as a vacuolar exporter of strictosidine. This is the first example of alkaloid transport by the NPF and also of an NPF member involved in controlling vacuolar sequestration of a specialized metabolite.

HH Nour-Eldin, SR Madsen, S Engelen et al. (2017)
Reduction of antinutritional glucosinolates in Brassica oilseeds by mutation of genes encoding transporters.
Nat Biotechnol 35: 377-382. https://doi.org/10.1038/nbt.3823

A translational approach wherein the gtr loss-of-function phenotype was translated from model plant Arabidopsis to Brassica juncea. Four out of 12 GTR orthologs were mutated and shown to reduce seed-gls content by ∼60% in field trials.

H Nour-Eldin, T Andersen, M Burow et al. (2012)
NRT/PTR transporters are essential for translocation of glucosinolate defence compounds to seeds.
Nature 488: 531–534. https://doi.org/10.1038/nature11285

Through a functional genomics approach the authors screened a library of 239 Arabidopsis transporters in Xenopus oocytes and identified the GTRs as glucosinolate transporters essential for seed accumulation. This study was the first to link the NPF to PSM.

JW Rensvold, E Shishkova, Y Sverchkov et al. (2022)
Defining mitochondrial protein functions through deep multiomic profiling
Nature 606:382–388. https://doi.org/10.1038/s41586-022-04765-3

While many core protein components of mitochondria are known, clear functions of those proteins are often still lacking. The authors determined the biomolecule profile of > 200 cell lines with different mitochondrial gene knockouts, using a mass spectrometry-based multiomics approach. They built the interactive online MITOMICS resource, which provides a deep survey of the cellular responses to mitochondrial perturbations.

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