title: Thaumatin-like proteins are differentially expressed and localized in phloem tissues of hybrid poplar.
abstract: BACKGROUND
  Two thaumatin-like proteins (TLPs) were previously identified in phloem exudate of hybrid poplar (Populus trichocarpa x P. deltoides) using proteomics methods, and their sieve element localization confirmed by immunofluorescence. In the current study, we analyzed different tissues to further understand TLP expression and localization in poplar, and used immunogold labelling to determine intracellular localization.
  
  
  RESULTS
  Immunofluorescence using a TLP antiserum confirmed the presence of TLP in punctate, organelle-like structures within sieve elements. On western blots, the antiserum labeled two constitutively expressed proteins with distinct expression patterns. Immunogold labelling suggested that TLPs are associated with starch granules and starch-containing plastids in sieve elements and phloem parenchyma cells. In addition, the antiserum recognized TLPs in the inner cell wall and sieve plate region of sieve elements.
  
  
  CONCLUSIONS
  TLP localization in poplar cells and tissues is complex. TLP1 is expressed predominantly in tissues with a prominent vascular system such as midveins, petioles and stems, whereas the second TLP is primarily expressed in starch-storing plastids found in young leaves and the shoot apex.
authors.affiliation: Department of Biology, University of Victoria, Victoria, BC, Canada.
authors.forename: Nicole J
authors.initials: NJ
authors.lastname: Dafoe
authors.forename: Brent E
authors.initials: BE
authors.lastname: Gowen
authors.forename: C Peter
authors.initials: CP
authors.lastname: Constabel
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002678:Chimera; D008969:Molecular Sequence Data; D052585:Phloem / Q000737:chemistry / Q000378:metabolism*; D018515:Plant Leaves / Q000235:genetics; D010940:Plant Proteins / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D032107:Populus / Q000737:chemistry / Q000378:metabolism*; D040901:Proteomics / Q000379:methods
chemical_list: D010940:Plant Proteins; C003427:thaumatin protein, plant
references.citation: Plant J. 1999 Aug;19(4):473-80
references.pmid: 10504569
references.citation: Biochem J. 2007 May 1;403(3):583-91
references.pmid: 17269932
references.citation: Mol Plant Microbe Interact. 2007 Jan;20(1):82-93
references.pmid: 17249425
references.citation: Ann Bot. 2006 Sep;98(3):555-64
references.pmid: 16877456
references.citation: J Mol Biol. 2003 Jun 13;329(4):721-30
references.pmid: 12787673
references.citation: J Proteome Res. 2009 May;8(5):2341-50
references.pmid: 19245218
references.citation: Nat Struct Biol. 1996 Jan;3(1):19-23
references.pmid: 8548448
references.citation: Planta. 1998 Aug;205(4):514-21
references.pmid: 9684355
references.citation: Plant Physiol. 2007 May;144(1):347-66
references.pmid: 17400708
references.citation: Biochimie. 2006 Jan;88(1):45-52
references.pmid: 16085352
references.citation: Tree Physiol. 2007 Dec;27(12):1649-59
references.pmid: 17938097
references.citation: Proteins. 2004 Jan 1;54(1):170-3
references.pmid: 14705035
references.citation: J Mol Biol. 1999 Mar 5;286(4):1137-45
references.pmid: 10047487
references.citation: Arch Virol. 1991;120(1-2):97-107
references.pmid: 1929881
references.citation: J Microsc. 1997 Aug;187(Pt 2):77-84
references.pmid: 9316269
references.citation: Phytopathology. 2007 Nov;97(11):1406-14
references.pmid: 18943509
references.citation: Plant Physiol. 1993 Mar;101(3):873-880
references.pmid: 12231738
references.citation: Plant Physiol. 1997 Oct;115(2):463-9
references.pmid: 9342866
references.citation: Plant Physiol. 1998 Jun;117(2):465-72
references.pmid: 9625699
references.citation: Plant Physiol. 2007 Feb;143(2):866-75
references.pmid: 17189328
references.citation: Plant Physiol. 2007 Feb;143(2):849-65
references.pmid: 17189325
references.citation: Nature. 1970 Aug 15;227(5259):680-5
references.pmid: 5432063
references.citation: Biochimie. 2003 Jan-Feb;85(1-2):123-31
references.pmid: 12765782
references.citation: J Exp Bot. 2006;57(4):767-74
references.pmid: 16495410
references.citation: Planta. 2002 Apr;214(6):853-62
references.pmid: 11941461
references.citation: Plant Mol Biol. 2001 Jun;46(3):347-59
references.pmid: 11488481
references.citation: Mol Plant Microbe Interact. 2007 Jul;20(7):816-31
references.pmid: 17601169
references.citation: Plant Physiol. 1998 Dec;118(4):1431-8
references.pmid: 9847118
references.citation: Plant Physiol. 1996 May;111(1):269-73
references.pmid: 8685266
references.citation: New Phytol. 2006;172(4):617-35
references.pmid: 17096789
references.citation: Eur J Biochem. 2001 Aug;268(15):4190-9
references.pmid: 11488912
references.citation: Phytopathology. 2004 Nov;94(11):1235-43
references.pmid: 18944459
references.citation: Trends Plant Sci. 2002 Mar;7(3):126-32
references.pmid: 11906836
references.citation: Appl Environ Microbiol. 2001 May;67(5):2365-6
references.pmid: 11319124
references.citation: Annu Rev Plant Biol. 2006;57:203-32
references.pmid: 16669761
references.citation: Annu Rev Phytopathol. 2006;44:135-62
references.pmid: 16602946
references.citation: Appl Environ Microbiol. 2001 Jul;67(7):2883-94
references.pmid: 11425698
references.citation: Plant Cell. 2002 Dec;14(12):3073-88
references.pmid: 12468728