LePLDβ1 activation and relocalization in suspension-cultured tomato cells treated with xylanase
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, LePLDβ1, 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 LePLDβ1 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, LePLDβ1-silenced cell-suspension cultures were found to have increased polyphenol oxidase activity, to secrete less of the β-d-xylosidase LeXYL2 and to secrete and express more of the xyloglucan-specific endoglucanase inhibitor protein XEGIP. Using an LePLDβ1–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 PLDβ in plant–pathogen interactions are discussed.
Document Type: Research Article
Affiliations: 1: Section of Plant Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, Kruislaan 318, NL-1098 SM, Amsterdam, The Netherlands 2: Instituto de Investigaciones Biológicas, Facultad de Ciencas Exactas y Naturales, Universidad Nacional de Mar del Plata, CC 1245, 7600 Mar del Plata, Argentina 3: Mass Spectrometry Group, Swammerdam Institute for Life Sciences, University of Amsterdam, Nieuwe Achtergracht 166, NL-1018 WS, Amsterdam, The Netherlands
Publication date: February 1, 2006