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Open Access item Thiol synthetases of legumes: immunogold localization and differential gene regulation by phytohormones

Authors:Clemente, María Rebeca
Bustos-Sanmamed, Pilar
Loscos Aranda, Jorge
James, Euan K.
Pérez-Rontomé, Carmen
Navascués Ortega, Joaquín
Gay, Marina
Becana Ausejo, Manuel
Keywords:γ-Glutamylcysteine synthetase, (homo)glutathione synthetase, immunogold localization, legumes, phytohormones, plant stress
Issue Date:Jun-2012
Publisher:Oxford University Press
Citation:Clemente MR, Bustos-Sanmamed P, Loscos J, James EK, Pérez-Rontomé C, Navascués J, Gay M, Becana M. Thiol synthetases of legumes: immunogold localization and differential gene regulation by phytohormones. Journal of Experimental Botany 63 (10): 3923-3934 (2012)
Abstract:In plants and other organisms, glutathione (GSH) biosynthesis is catalysed sequentially by γ-glutamylcysteine synthetase (γECS) and glutathione synthetase (GSHS). In legumes, homoglutathione (hGSH) can replace GSH and is synthesized by γECS and a specific homoglutathione synthetase (hGSHS). The subcellular localization of the enzymes was examined by electron microscopy in several legumes and gene expression was analysed in Lotus japonicus plants treated for 1–48 h with 50 μM of hormones. Immunogold localization studies revealed that γECS is confined to chloroplasts and plastids, whereas hGSHS is also in the cytosol. Addition of hormones caused differential expression of thiol synthetases in roots. After 24–48 h, abscisic and salicylic acids downregulated GSHS whereas jasmonic acid upregulated it. Cytokinins and polyamines activated GSHS but not γECS or hGSHS. Jasmonic acid elicited a coordinated response of the three genes and auxin induced both hGSHS expression and activity. Results show that the thiol biosynthetic pathway is compartmentalized in legumes. Moreover, the similar response profiles of the GSH and hGSH contents in roots of non-nodulated and nodulated plants to the various hormonal treatments indicate that thiol homeostasis is independent of the nitrogen source of the plants. The differential regulation of the three mRNA levels, hGSHS activity, and thiol contents by hormones indicates a fine control of thiol biosynthesis at multiple levels and strongly suggests that GSH and hGSH play distinct roles in plant development and stress responses.
Description:32 Pags., 6 Figs. The definitive version is available at: http://jxb.oxfordjournals.org/
Publisher version (URL):http://dx.doi.org/10.1093/jxb/ers083
URI:http://hdl.handle.net/10261/56960
ISSN:0022-0957
E-ISSNmetadata.dc.identifier.doi = DOI:1460-2431
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Appears in Collections:(EEAD) Artículos

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