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First published online March 10, 2006; 10.1104/pp.106.077982 Plant Physiology 141:446-455 (2006) © 2006 American Society of Plant Biologists
Maturation of Arabidopsis Seeds Is Dependent on Glutathione Biosynthesis within the Embryo1,[C]Department of Genetics, University of Melbourne, Parkville, Victoria 3010, Australia (N.G.C., C.S.C.); and Heidelberg Institute of Plant Sciences, University of Heidelberg, D–69120 Heidelberg, Germany (M.P., A.W., A.J.M.)
Glutathione (GSH) has been implicated in maintaining the cell cycle within plant meristems and protecting proteins during seed dehydration. To assess the role of GSH during development of Arabidopsis (Arabidopsis thaliana [L.] Heynh.) embryos, we characterized T-DNA insertion mutants of GSH1, encoding the first enzyme of GSH biosynthesis,
1 This work was supported by grants from the Deutsche Forschungsgemeinschaft (grant no. ME 1567/3–2 to A.J.M.), the University of Heidelberg (to A.J.M.), and the University of Melbourne (to C.S.C.). 2 Present address: Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06511. 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: Andreas J. Meyer (ameyer{at}hip.uni-hd.de). [C] Some figures in this article are displayed in color online but in black and white in the print edition. Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.106.077982. * Corresponding author; e-mail ameyer{at}hip.uni-hd.de; fax 49–6221–545859. Received January 27, 2006; returned for revision February 21, 2006; accepted February 22, 2006. This article has been cited by other articles:
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-glutamyl-cysteine synthetase. These gsh1 mutants confer a recessive embryo-lethal phenotype, in contrast to the previously described GSH1 mutant, root meristemless 1(rml1), which is able to germinate, but is deficient in postembryonic root development. Homozygous mutant embryos show normal morphogenesis until the seed maturation stage. The only visible phenotype in comparison to wild type was progressive bleaching of the mutant embryos from the torpedo stage onward. Confocal imaging of GSH in isolated mutant and wild-type embryos after fluorescent labeling with monochlorobimane detected residual amounts of GSH in rml1 embryos. In contrast, gsh1 T-DNA insertion mutant embryos could not be labeled with monochlorobimane from the torpedo stage onward, indicating the absence of GSH. By using high-performance liquid chromatography, however, GSH was detected in extracts of mutant ovules and imaging of intact ovules revealed a high concentration of GSH in the funiculus, within the phloem unloading zone, and in the outer integument. The observation of high GSH in the funiculus is consistent with a high GSH1-promoter::
-glucuronidase reporter activity in this tissue. Development of mutant embryos could be partially rescued by exogenous GSH in vitro. These data show that at least a small amount of GSH synthesized autonomously within the developing embryo is essential for embryo development and proper seed maturation. 
