Cytosolic localization in tomato mesophyll cells of a novel glutamine synthetase induced in response to bacterial infection or phosphinothricin treatment

• Type: Article in International Scientific Journal
• Date: 1998

Authors

Perez Garcia, A (Author) Other; Pereira, S (Author) FCUP; Pissarra, J (Author) FCUP; Gutierrez, AG (Author) Other; Cazorla, FM (Author) Other; Salema, R (Author) FCUP; de Vicente, A (Author) Other; Canovas, FM (Author) Other

Journal

Title: Planta

Vol. 206

Pages: 426-434

ISSN: 0032-0935

Publisher: Springer Nature

Indexing

ISI Web of Knowledge - 58 Citations

Scopus - 60 Citations

Scientific classification

FOS: Natural sciences > Biological sciences

Other information

Authenticus ID: P-001-724

DOI: 10.1007/s004250050418

Abstract (EN): In tomato (Lycopersicon esculentum Mill.) leaves, the predominant glutamine synthetase (GS; EC 6.3.1.2) is chloroplastic (GS2; 45 kDa) whereas the cytosolic isoform (GS1; 39 kDa) is represented as a minor enzyme. Following either infection by Pseudomonas syringae pv. tomato (Pst) or treatment with phosphinothricin (PPT), a GS inhibitor, GS1 accumulated in the leaves. In contrast to healthy control leaves, where GS1 was restricted to the veins, in infected and PPT-treated leaves the GS1 polypeptide was also detected in the leaf blade; moreover, it was more abundant than GS2. Different immunological approaches were therefore used to investigate whether or not the GS1 polypeptide expressed in Pst-infected and PPT-treated tomato leaves was distributed among different tissues and subcellular compartments in the same way as the constitutive GS1 expressed in healthy leaves. By tissue-printing analysis, a similar GS immunostaining was observed in epidermis, mesophyll and phloem of leaflet midrib cross-sections of control, infected and PPT-treated leaves. Immunocytochemical localization revealed that GS protein was present in the chloroplast of mesophyll cells and the cytoplasm of phloem cells in healthy leaves; however, in Pst-infected or PPT-treated leaves, a strong labelling was observed in the cytoplasm of mesophyll cells. Two-dimensional analysis of GS polypeptides showed that, in addition to the constitutive GS1, a GS1 polypeptide different in charge was present in tomato leaflets after microbial infection or herbicide treatment. All these results indicate that a novel cytosolic GS is induced in mesophyll cells of Pst-infected or PPT-treated leaves. A possible role for this new cytosolic GS in the remobilization of leaf nitrogen during infection is proposed.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 9