Journal Article

Up-Regulation and Localization of Asparagine Synthetase in Tomato Leaves Infected by the Bacterial Pathogen <i>Pseudomonas syringae</i>

Francisco Olea, Alejandro Pérez-García, Francisco R. Cantón, M. Eugenia Rivera, Rafael Cañas, Concepción Ávila, Francisco M. Cazorla, Francisco M. Cánovas and Antonio de Vicente

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 45, issue 6, pages 770-780
Published in print June 2004 | ISSN: 0032-0781
Published online June 2004 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pch092
Up-Regulation and Localization of Asparagine Synthetase in Tomato Leaves Infected by the Bacterial Pathogen Pseudomonas syringae

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  • Biochemistry
  • Molecular and Cell Biology
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Nitrogen metabolism is one aspect of basic metabolism, which is still quite unknown in the field of plant–pathogen interactions. Evidence derived from previous studies conducted in our laboratory strongly suggests that during microbial pathogenesis an important nitrogen mobilization process takes place in diseased tissues. Here we describe the expression pattern of asparagine synthetase (AS; EC 6.3.5.4) in tomato leaves infected by the bacterial pathogen Pseudomonas syringae pv. tomato. Using an homologous AS cDNA probe isolated by RT-PCR from infected leaves, we have observed a high level induction of AS expression during the course of infection. Concomitantly, a single AS polypeptide also accumulated in response to bacterial infection. Furthermore, immunohistochemical analysis of AS in infected leaves revealed a strong immunostaining in phloem cells of the main vascular bundles and in secondary veins of the leaf blade. These data correlate with those previously reported for expression of a cytosolic isoform of glutamine synthetase (GS1) also induced during development of the infectious process. Taken together, our results suggest the existence of a GS1/AS pathway representing a metabolic route for transferring ammonium released from protein catabolism into asparagine, an amino acid that may have a major role in nitrogen mobilization from diseased tissues.

Keywords: Keywords: Asparagine synthetase (EC 6.3.5.4) — Bacterial pathogenesis — Glutamine synthetase — Nitrogen mobilization — Pseudomonas syringae — Tomato (Lycopersicon esculentum Mill.).; Abbreviations: AS, asparagine synthetase; GS1, cytosolic glutamine synthetase; GS2, chloroplastic glutamine synthetase.

Journal Article.  6868 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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