title: LePLDbeta1 activation and relocalization in suspension-cultured tomato cells treated with xylanase.
abstract: Phospholipase D (PLD) has been implicated in various cellular processes including membrane degradation, vesicular trafficking and signal transduction. Previously, we described a PLD gene family in tomato (Lycopersicon esculentum) and showed that expression of one of these genes, LePLDbeta1, was induced by treatment with the fungal elicitor xylanase. To further investigate the function of this PLD, a gene-specific RNAi construct was used to knock down levels of LePLDbeta1 transcript in suspension-cultured tomato cells. Silenced cells exhibited a strong decrease in xylanase-induced PLD activity and responded to xylanase treatment with a disproportionate oxidative burst. Furthermore, LePLDbeta1-silenced cell-suspension cultures were found to have increased polyphenol oxidase activity, to secrete less of the beta-d-xylosidase LeXYL2 and to secrete and express more of the xyloglucan-specific endoglucanase inhibitor protein XEGIP. Using an LePLDbeta1-green fluorescent protein (GFP) fusion protein for confocal laser scanning microscopy-mediated localization studies, untreated cells displayed a cytosolic localization, whereas treatment with xylanase induced relocalization to punctuate structures within the cytosol. Possible functions for PLDbeta in plant-pathogen interactions are discussed.
authors.affiliation: Section of Plant Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, Kruislaan 318, NL-1098 SM, Amsterdam, The Netherlands.
authors.forename: Bastiaan O R
authors.initials: BO
authors.lastname: Bargmann
authors.forename: Ana M
authors.initials: AM
authors.lastname: Laxalt
authors.forename: Bas Ter
authors.initials: BT
authors.lastname: Riet
authors.forename: Elske
authors.initials: E
authors.lastname: Schouten
authors.forename: Wessel
authors.initials: W
authors.lastname: van Leeuwen
authors.forename: Henk L
authors.initials: HL
authors.lastname: Dekker
authors.forename: Chris G
authors.initials: CG
authors.lastname: de Koster
authors.forename: Michel A
authors.initials: MA
authors.lastname: Haring
authors.forename: Teun
authors.initials: T
authors.lastname: Munnik
mesh_terms: D004156:Catechol Oxidase / Q000378:metabolism; D002478:Cells, Cultured; D043364:Endo-1,4-beta Xylanases / Q000494:pharmacology*; D020868:Gene Silencing; D049452:Green Fluorescent Proteins / Q000032:analysis; D018551:Solanum lycopersicum / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D005810:Multigene Family / Q000502:physiology; D010641:Phenotype; D010739:Phospholipase D / Q000032:analysis* / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction; D014995:Xylosidases / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D017382:Reactive Oxygen Species; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D004156:Catechol Oxidase; D010739:Phospholipase D; D014995:Xylosidases; C026579:exo-1,4-beta-D-xylosidase; D043364:Endo-1,4-beta Xylanases