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First published online March 10, 2006; 10.1104/pp.106.079855 Plant Physiology 141:75-84 (2006) © 2006 American Society of Plant Biologists Plastid Cues Posttranscriptionally Regulate the Accumulation of Key Enzymes of the Methylerythritol Phosphate Pathway in Arabidopsis1Departament de Bioquímica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona, 08028 Barcelona, Spain (S.S.-G., P.B.-P., U.F.-P., A.B., M.R.-C.); Institució Catalana de Recerca i Estudis Avançats-Consorci Consejo Superior de Investigaciones Científicas-Institut de Recerca i Tecnologia Agroalimentàries, 08034 Barcelona, Spain (J.F.M.-G.); and Departamento de Biología Molecular de Plantas, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62271, Mexico (C.S.R., P.L.)
Plastid isoprenoids (including hormones and photosynthetic pigments) are essential for plant growth and development, but relatively little is known of how the production of their metabolic precursors via the recently elucidated methylerythritol phosphate (MEP) pathway is regulated. We have identified an Arabidopsis (Arabidopsis thaliana) mutant that survives an otherwise lethal block of the MEP pathway with fosmidomycin (FSM). In rif10 (resistant to inhibition with FSM 10) plants, the accumulation of flux-controlling enzymes of the pathway is posttranscriptionally up-regulated. Strikingly, this phenotype is linked to a lower accumulation of plastidial isoprenoid pigments such as chlorophylls and carotenoids, resulting in mutant plants that are paler and smaller than the wild type. The rif10 mutant is impaired in plastid RNA processing due to a T-DNA insertion in the coding region of the At3g03710 gene encoding the chloroplast-targeted exoribonuclease polyribonucleotide phosphorylase. FSM resistance and other rif10-like phenotypes were also observed in wild-type Arabidopsis, tomato (Lycopersicon esculentum), and rice (Oryza sativa) seedlings grown in the presence of sublethal concentrations of chloramphenicol (an inhibitor of protein synthesis in plastids). By contrast, treatment with norflurazon (an inhibitor of carotenoid biosynthesis causing a similar pale cotyledon phenotype) did not result in FSM resistance. Together, the results support that plastome-encoded proteins are involved in negatively regulating the posttranscriptional accumulation of specific nuclear-encoded MEP pathway enzymes in chloroplasts. Regulation of the MEP pathway by a mechanism dependent on plastid cues might function under physiological conditions to finely adjust plastidial isoprenoid biosynthesis to the metabolic capabilities or requirements of plastids.
1 This work was supported by the Spanish Ministerio de Ciencia y Tecnología and Fondo Europeo de Desarrollo Regional (grant nos. BIO200500367 to M.R.C., BMC200306833 to A.B., and BIO200200298 to J.F.M.-G.), by the Mexican Dirección General de Asuntos para el Personal Académico (grant no. IN2045033), by the Howard Hughes Medical Institute (to P.L.), by the Generalitat de Catalunya (Ph.D. fellowship to S.S.-G.), and by the Spanish Ministerio de Educación y Ciencia (Ph.D. fellowships to U.F. and P.B.-P.). 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: Manuel Rodríguez-Concepción (mrodrigu{at}sun.bq.ub.es). Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.106.079855. * Corresponding author; e-mail mrodrigu{at}sun.bq.ub.es; fax 34934021559. Received February 28, 2006; returned for revision February 28, 2006; accepted March 5, 2006. This article has been cited by other articles:
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