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First published online September 20, 2007; 10.1104/pp.107.105593 Plant Physiology 145:946-960 (2007) © 2007 American Society of Plant Biologists OPEN ACCESS ARTICLE
Localization in Roots and Flowers of Pea Chloroplastic Thioredoxin f and Thioredoxin m Proteins Reveals New Roles in Nonphotosynthetic Organs1,[OA]Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, 18008 Granada, Spain
Plant thioredoxins (TRXs) are involved in redox regulation of a wide variety processes and usually exhibit organ specificity. We report strong evidence that chloroplastic TRXs are localized in heterotrophic tissues and suggest some ways in which they might participate in several metabolic and developmental processes. The promoter regions of the chloroplastic f and m1 TRX genes were isolated from a pea (Pisum sativum) plant genomic bank. Histochemical staining for
1 This work was supported by the Ministerio de Educación y Ciencia (Spain; grant nos. BFI2002–00401 and BIO2005–00157) and the Junta de Andalucía (Spain; grant no. CVI–154). J.d.D.B.-L. was supported by a predoctoral fellowship from the Junta de Andalucía and A.S.R. was supported by a postdoctoral I3P fellowship from the Consejo Superior de Investigaciones Científicas (Spain). The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Mariam Sahrawy (mariam.sahrawy{at}eez.csic.es). [OA] Open Access articles can be viewed online without a subscription. www.plantphysiol.org/cgi/doi/10.1104/pp.107.105593 * Corresponding author; e-mail mariam.sahrawy{at}eez.csic.es. Received July 16, 2007; accepted September 10, 2007; published September 20, 2007. This article has been cited by other articles:
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-glucuronidase (GUS) in transgenic homozygous Arabidopsis (Arabidopsis thaliana) plants showed preferential expression of the 444-bp PsTRXf1 promoter in early seedlings, stems, leaves, and roots, as well as in flowers, stigma, pollen grains, and filaments. GUS activity under the control of the 1,874-bp PsTRXm1 promoter was restricted to the leaves, roots, seeds, and flowers. To gain insight into the translational regulation of these genes, a series of deletions of 5' elements in both TRX promoters were analyzed. The results revealed that a 126-bp construct of the PsTRXf2 promoter was unable to reproduce the expression pattern observed with the full promoter. The differences in expression and tissue specificity between PsTRXm1 and the deleted promoters PsTRXm2 and PsTRXm3 suggest the existence of upstream positive or negative regulatory regions that affect tissue specificity, sucrose metabolism, and light regulation. PsTRXm1 expression is finely regulated by light and possibly by other metabolic factors. In situ hybridization experiments confirmed new localizations of these chloroplastic TRX transcripts in vascular tissues and flowers, and therefore suggest possible new functions in heterotrophic tissues related to cell division, germination, and plant reproduction. 
