title: Putting the Squeeze on Plasmodesmata: A Role for Reticulons in Primary Plasmodesmata Formation.
abstract: Primary plasmodesmata (PD) arise at cytokinesis when the new cell plate forms. During this process, fine strands of endoplasmic reticulum (ER) are laid down between enlarging Golgi-derived vesicles to form nascent PD, each pore containing a desmotubule, a membranous rod derived from the cortical ER. Little is known about the forces that model the ER during cell plate formation. Here, we show that members of the reticulon (RTNLB) family of ER-tubulating proteins in Arabidopsis (Arabidopsis thaliana) may play a role in the formation of the desmotubule. RTNLB3 and RTNLB6, two RTNLBs present in the PD proteome, are recruited to the cell plate at late telophase, when primary PD are formed, and remain associated with primary PD in the mature cell wall. Both RTNLBs showed significant colocalization at PD with the viral movement protein of Tobacco mosaic virus, while superresolution imaging (three-dimensional structured illumination microscopy) of primary PD revealed the central desmotubule to be labeled by RTNLB6. Fluorescence recovery after photobleaching studies showed that these RTNLBs are mobile at the edge of the developing cell plate, where new wall materials are being delivered, but significantly less mobile at its center, where PD are forming. A truncated RTNLB3, unable to constrict the ER, was not recruited to the cell plate at cytokinesis. We discuss the potential roles of RTNLBs in desmotubule formation.
authors.affiliation: Institute of Molecular Plant Sciences, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom (K.K., K.O.);Plant Cell Biology, Oxford Brookes University, Oxford OX3 0BP, United Kingdom (P.W., V.K., C.H.);Biomedical Sciences Research Complex, University of St. Andrews, St. Andrews KY16 9ST, United Kingdom (J.T.);Life Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom (L.F.); andBiosciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, United Kingdom (I.S.).
authors.forename: Kirsten
authors.identifier: http://orcid.org/0000-0002-5487-1763
authors.initials: K
authors.lastname: Knox
authors.affiliation: Institute of Molecular Plant Sciences, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom (K.K., K.O.);Plant Cell Biology, Oxford Brookes University, Oxford OX3 0BP, United Kingdom (P.W., V.K., C.H.);Biomedical Sciences Research Complex, University of St. Andrews, St. Andrews KY16 9ST, United Kingdom (J.T.);Life Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom (L.F.); andBiosciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, United Kingdom (I.S.).
authors.forename: Pengwei
authors.identifier: http://orcid.org/0000-0002-0362-878X
authors.initials: P
authors.lastname: Wang
authors.affiliation: Institute of Molecular Plant Sciences, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom (K.K., K.O.);Plant Cell Biology, Oxford Brookes University, Oxford OX3 0BP, United Kingdom (P.W., V.K., C.H.);Biomedical Sciences Research Complex, University of St. Andrews, St. Andrews KY16 9ST, United Kingdom (J.T.);Life Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom (L.F.); andBiosciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, United Kingdom (I.S.).
authors.forename: Verena
authors.identifier: http://orcid.org/0000-0003-3782-5834
authors.initials: V
authors.lastname: Kriechbaumer
authors.affiliation: Institute of Molecular Plant Sciences, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom (K.K., K.O.);Plant Cell Biology, Oxford Brookes University, Oxford OX3 0BP, United Kingdom (P.W., V.K., C.H.);Biomedical Sciences Research Complex, University of St. Andrews, St. Andrews KY16 9ST, United Kingdom (J.T.);Life Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom (L.F.); andBiosciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, United Kingdom (I.S.).
authors.forename: Jens
authors.identifier: http://orcid.org/0000-0003-3873-0650
authors.initials: J
authors.lastname: Tilsner
authors.affiliation: Institute of Molecular Plant Sciences, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom (K.K., K.O.);Plant Cell Biology, Oxford Brookes University, Oxford OX3 0BP, United Kingdom (P.W., V.K., C.H.);Biomedical Sciences Research Complex, University of St. Andrews, St. Andrews KY16 9ST, United Kingdom (J.T.);Life Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom (L.F.); andBiosciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, United Kingdom (I.S.).
authors.forename: Lorenzo
authors.identifier: http://orcid.org/0000-0003-4100-6022
authors.initials: L
authors.lastname: Frigerio
authors.affiliation: Institute of Molecular Plant Sciences, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom (K.K., K.O.);Plant Cell Biology, Oxford Brookes University, Oxford OX3 0BP, United Kingdom (P.W., V.K., C.H.);Biomedical Sciences Research Complex, University of St. Andrews, St. Andrews KY16 9ST, United Kingdom (J.T.);Life Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom (L.F.); andBiosciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, United Kingdom (I.S.).
authors.forename: Imogen
authors.initials: I
authors.lastname: Sparkes
authors.affiliation: Institute of Molecular Plant Sciences, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom (K.K., K.O.);Plant Cell Biology, Oxford Brookes University, Oxford OX3 0BP, United Kingdom (P.W., V.K., C.H.);Biomedical Sciences Research Complex, University of St. Andrews, St. Andrews KY16 9ST, United Kingdom (J.T.);Life Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom (L.F.); andBiosciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, United Kingdom (I.S.).
authors.forename: Chris
authors.identifier: http://orcid.org/0000-0003-4856-7690
authors.initials: C
authors.lastname: Hawes
authors.affiliation: Institute of Molecular Plant Sciences, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom (K.K., K.O.);Plant Cell Biology, Oxford Brookes University, Oxford OX3 0BP, United Kingdom (P.W., V.K., C.H.);Biomedical Sciences Research Complex, University of St. Andrews, St. Andrews KY16 9ST, United Kingdom (J.T.);Life Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom (L.F.); andBiosciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, United Kingdom (I.S.) karl.oparka@ed.ac.uk.
authors.forename: Karl
authors.initials: K
authors.lastname: Oparka
mesh_terms: D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002473:Cell Wall / Q000235:genetics / Q000378:metabolism*; D048749:Cytokinesis; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D036681:Fluorescence Recovery After Photobleaching; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D018613:Microscopy, Confocal; D053830:Plant Viral Movement Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D031425:Plasmodesmata / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D014026:Nicotiana / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D014027:Tobacco Mosaic Virus / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D008565:Membrane Proteins; D053830:Plant Viral Movement Proteins; C000607430:RTNLB3 protein, Arabidopsis; C000607431:reticulon-like protein B6, Arabidopsis; D049452:Green Fluorescent Proteins