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Sphingolipid biosynthesis modulates plasmodesmal ultrastructure and phloem unloading

Yan, Dawei and Yadav, Shri Ram and Paterlini, Andrea and Nicolas, William J. and Petit, Jules D. and Brocard, Lysiane and Belevich, Ilya and Grison, Magali S. and Vatén, Anne and Karami, Leila and el-Showk, Sedeer and Lee, Jung-Youn and Murawska, Gosia M. and Mortimer, Jenny and Knoblauch, Michael and Jokitalo, Eija and Markham, Jonathan E. and Bayer, Emmanuelle M. and Helariutta, Ykä (2019) Sphingolipid biosynthesis modulates plasmodesmal ultrastructure and phloem unloading. Nature Plants, 5 (6). pp. 604-615. ISSN 2055-0278. PMCID PMC6565433.

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During phloem unloading, multiple cell-to-cell transport events move organic substances to the root meristem. Although the primary unloading event from the sieve elements to the phloem pole pericycle has been characterized to some extent, little is known about post-sieve element unloading. Here, we report a novel gene, PHLOEM UNLOADING MODULATOR (PLM), in the absence of which plasmodesmata-mediated symplastic transport through the phloem pole pericycle–endodermis interface is specifically enhanced. Increased unloading is attributable to a defect in the formation of the endoplasmic reticulum–plasma membrane tethers during plasmodesmal morphogenesis, resulting in the majority of pores lacking a visible cytoplasmic sleeve. PLM encodes a putative enzyme required for the biosynthesis of sphingolipids with very-long-chain fatty acid. Taken together, our results indicate that post-sieve element unloading involves sphingolipid metabolism, which affects plasmodesmal ultrastructure. They also raise the question of how and why plasmodesmata with no cytoplasmic sleeve facilitate molecular trafficking.

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URLURL TypeDescription ReadCube access CentralArticle
Yan, Dawei0000-0001-8256-0279
Paterlini, Andrea0000-0002-1777-3160
Belevich, Ilya0000-0003-2190-4909
Mortimer, Jenny0000-0001-6624-636X
Bayer, Emmanuelle M.0000-0001-8642-5293
Helariutta, Ykä0000-0002-7287-8459
Additional Information:© 2019 Springer Nature Publishing AG. Received 03 September 2018; Accepted 17 April 2019; Published 10 June 2019. Data availability: All data underlying the findings are available from the corresponding authors on request. This work was supported by the Finnish Centre of Excellence in Molecular Biology of Primary Producers (Academy of Finland CoE program 2014–2019, decision no. 271832), the Gatsby Foundation (GAT3395/PR3), the National Science Foundation Biotechnology and Biological Sciences Research Council grant (BB/N013158/1), the University of Helsinki (award 799992091), the European Research Council Advanced Investigator Grant SYMDEV (no. 323052) and the European Research Council under the European Union’s Horizon 2020 research and innovation programme (grant no. 772103-BRIDGING to E.M.B.). J.D.P. is funded by a PhD fellowship from the Formation à la Recherche dans l’Industrie et l’Agriculture (grant no. 1.E.096.18), Belgium. This work was also funded as part of the US Department of Energy Joint BioEnergy Institute ( supported by the US Department of Energy, Office of Science, Office of Biological and Environmental Research, through contract DE-AC02-05CH11231 between the Lawrence Berkeley National Laboratory and the US Department of Energy. We thank R. Wightman for assistance with confocal imaging, M. Bourdon for help in conducting immunolocalization and K. Abley for help with the seed germination assay. The SB-EM imaging was supported by the Biocenter Finland (I.B. and E.J.), and we thank M. Lindman, A. Salminen and M. Veikkolainen for sample preparation for SB-EM. We thank M. Roth and R. Welti for polar lipid analysis, A. Shevchenko and K. Schuchmann for sphingomyelin analysis and P. Dupree for data interpretation. Electron tomography was performed at the plant pole of the Bordeaux Imaging Centre ( The Region Aquitaine also supported the acquisition of the electron microscope (grant no. 2011 13 04 007 PFM), and FranceBioImaging Infrastructure supported the acquisition of the AFS2 and ultra-microtome. The sterol analyses were performed at the Functional Genomic Center of Bordeaux, Metabolome/Lipidome platform (, funded by Grant MetaboHUB-ANR-11-INBS-0010. Author Contributions: D.Y., A.P., S.R.Y., E.M.B. and Y.H. designed the experiments. D.Y., A.P., S.R.Y., E.M.B. and Y.H. wrote the manuscript with input from other authors. D.Y., S.R.Y., A.V. and J.-Y.L. generated the Arabidopsis lines. S.R.Y., A.V., L.K. and S.e.-S. carried out the suppressor screen and gene mapping. D.Y., S.R.Y. and A.P. performed the growth phenotype analysis. D.Y. and J.E.M. carried out the sphingolipid profiles, and M.S.G. carried out the sterol analyses. A.P., W.J.N., J.D.P. and L.B. carried out the electron tomography analysis with support from E.M.B. M.K. provided support for the FRAP experiment. A.P., E.J. and I.B. carried out the SB-EM analysis. G.M.M. and J.M. performed the GIPC glycosylation assay. J.D.P. carried out the transient co-expression assay. The rest of experiments were performed by D.Y. The authors declare no competing interests.
Funding AgencyGrant Number
Academy of Finland271832
Gatsby FoundationGAT3395/PR3
Biotechnology and Biological Sciences Research Council (BBSRC)BB/N013158/1
University of Helsinki799992091
European Research Council (ERC)323052
European Research Council (ERC)772103-BRIDGING
Formation à la Recherche dans l’Industrie et l’Agriculture1.E.096.18
Department of Energy (DOE)DE-AC02-05CH11231
Biocenter FinlandUNSPECIFIED
Region Aquitaine2011 13 04 007 PFM
FranceBioImaging InfrastructureUNSPECIFIED
Functional Genomic Center of BordeauxMetaboHUB-ANR-11-INBS-0010
Subject Keywords:Plant cell biology; Plant development; Plant physiology
Issue or Number:6
PubMed Central ID:PMC6565433
Record Number:CaltechAUTHORS:20190617-103007728
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:96458
Deposited By: Tony Diaz
Deposited On:17 Jun 2019 17:46
Last Modified:03 Oct 2019 21:22

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