Impact of clock-associated Arabidopsis pseudo-response regulators in metabolic coordination.
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 alpha-tocopherol, highlighting them as additional outputs of pseudo-response regulators. These findings indicated that mitochondrial functions are coupled with the circadian system in plants.
RIKEN Plant Science Center, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.
Atsushi
A
Fukushima
Miyako
M
Kusano
Norihito
N
Nakamichi
Makoto
M
Kobayashi
Naomi
N
Hayashi
Hitoshi
H
Sakakibara
Takeshi
T
Mizuno
Kazuki
K
Saito
D000040:Abscisic Acid / Q000096:biosynthesis; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D001683:Biological Clocks; D002338:Carotenoids / Q000096:biosynthesis; D002734:Chlorophyll / Q000096:biosynthesis; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D018745:Genome, Plant / Q000235:genetics; D005810:Multigene Family / Q000235:genetics; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D024502:alpha-Tocopherol / Q000378:metabolism
D029681:Arabidopsis Proteins; C114425:CCA1 protein, Arabidopsis; D014157:Transcription Factors; D002734:Chlorophyll; D002338:Carotenoids; D000040:Abscisic Acid; D024502:alpha-Tocopherol