title: Overexpression of Arabidopsis plasmodesmata germin-like proteins disrupts root growth and development.
abstract: In plants, a population of non-cell-autonomous proteins (NCAPs), including numerous transcription factors, move cell to cell through plasmodesmata (PD). In many cases, the intercellular trafficking of these NCAPs is regulated by their interaction with specific PD components. To gain further insight into the functions of this NCAP pathway, coimmunoprecipitation experiments were performed on a tobacco (Nicotiana tabacum) plasmodesmal-enriched cell wall protein preparation using as bait the NCAP, pumpkin (Cucurbita maxima) PHLOEM PROTEIN16 (Cm-PP16). A Cm-PP16 interaction partner, Nt-PLASMODESMAL GERMIN-LIKE PROTEIN1 (Nt-PDGLP1) was identified and shown to be a PD-located component. Arabidopsis thaliana putative orthologs, PDGLP1 and PDGLP2, were identified; expression studies indicated that, postgermination, these proteins were preferentially expressed in the root system. The PDGLP1 signal peptide was shown to function in localization to the PD by a novel mechanism involving the endoplasmic reticulum-Golgi secretory pathway. Overexpression of various tagged versions altered root meristem function, leading to reduced primary root but enhanced lateral root growth. This effect on root growth was corrected with an inability of these chimeric proteins to form stable PD-localized complexes. PDGLP1 and PDGLP2 appear to be involved in regulating primary root growth by controlling phloem-mediated allocation of resources between the primary and lateral root meristems.
authors.affiliation: Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA 95616, USA.
authors.forename: Byung-Kook
authors.initials: BK
authors.lastname: Ham
authors.forename: Gang
authors.initials: G
authors.lastname: Li
authors.forename: Byung-Ho
authors.initials: BH
authors.lastname: Kang
authors.forename: Fanchang
authors.initials: F
authors.lastname: Zeng
authors.forename: William J
authors.initials: WJ
authors.lastname: Lucas
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002473:Cell Wall; D028464:Cucurbita / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D006023:Glycoproteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D018522:Gravitropism; D047468:Immunoprecipitation; D009928:Organ Specificity; D010641:Phenotype; D052585:Phloem / Q000254:growth & development / Q000378:metabolism; D010802:Phylogeny; D010940:Plant Proteins / Q000378:metabolism*; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism / Q000648:ultrastructure; D030821:Plants, Genetically Modified; D031425:Plasmodesmata / Q000378:metabolism*; D025941:Protein Interaction Mapping; D021382:Protein Sorting Signals; D021381:Protein Transport; D011993:Recombinant Fusion Proteins; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D006023:Glycoproteins; D010940:Plant Proteins; D021382:Protein Sorting Signals; D011993:Recombinant Fusion Proteins; C583233:PDGLP1 protein, Arabidopsis; C583234:GL22 protein, Arabidopsis; C116564:PP16 protein, Cucurbita maxima