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Impact of clock-associated Arabidopsis pseudo-response regulators in metabolic coordination [Erratum: 2009 May, v. 106, no. 21, p. 8791.]

Fukushima, Atsushi, Kusano, Miyako, Nakamichi, Norihito, Kobayashi, Makoto, Hayashi, Naomi, Sakakibara, Hitoshi, Mizuno, Takeshi, Saito, Kazuki
Proceedings of the National Academy of Sciences of the United States of America 2009 v.106 no.17 pp. 7251-7256
Arabidopsis thaliana, circadian rhythm, plant physiology, metabolism, transcriptomics, transcriptome, metabolomics, metabolites, gas chromatography, mass spectrometry, mutants, biosynthesis, chlorophyll, carotenoids, abscisic acid, alpha-tocopherol, tricarboxylic acid cycle
In higher plants, the circadian clock controls a wide range of cellular processes such as photosynthesis and stress responses. Understanding metabolic changes in arrhythmic plants and determining output-related function of clock genes would help in elucidating circadian-clock mechanisms underlying plant growth and development. In this work, we investigated physiological relevance of PSEUDO-RESPONSE REGULATORS (PRR 9, 7, and 5) in Arabidopsis thaliana by transcriptomic and metabolomic analyses. Metabolite profiling using gas chromatography-time-of-flight mass spectrometry demonstrated well-differentiated metabolite phenotypes of seven mutants, including two arrhythmic plants with similar morphology, a PRR 9, 7, and 5 triple mutant and a CIRCADIAN CLOCK-ASSOCIATED 1 (CCA1)-overexpressor line. Despite different light and time conditions, the triple mutant exhibited a dramatic increase in intermediates in the tricarboxylic acid cycle. This suggests that proteins PRR 9, 7, and 5 are involved in maintaining mitochondrial homeostasis. Integrated analysis of transcriptomics and metabolomics revealed that PRR 9, 7, and 5 negatively regulate the biosynthetic pathways of chlorophyll, carotenoid and abscisic acid, and α-tocopherol, highlighting them as additional outputs of pseudo-response regulators. These findings indicated that mitochondrial functions are coupled with the circadian system in plants.