Iron Is Involved in the Maintenance of Circadian Period Length in Arabidopsis12[W][OA]

• Published in: Plant physiology (Bethesda) Vol. 161; no. 3; pp. 1409 - 1420
• Main Authors: Chen, Yong-Yi, Wang, Ying, Shin, Lung-Jiun, Wu, Jing-Fen, Shanmugam, Varanavasiappan, Tsednee, Munkhtsetseg, Lo, Jing-Chi, Chen, Chyi-Chuann, Wu, Shu-Hsing, Yeh, Kuo-Chen
• Format: Journal Article
• Language: English
• Published: American Society of Plant Biologists 10-01-2013
• Subjects: Signaling and Response
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.112.212068

Micronutrient iron regulates the plant circadian clock through a chloroplast retrograde signaling pathway.
The homeostasis of iron (
Fe
) in plants is strictly regulated to maintain an optimal level for plant growth and development but not cause oxidative stress. About 30% of arable land is considered
Fe
deficient because of calcareous soil that renders
Fe
unavailable to plants. Under
Fe
-deficient conditions, Arabidopsis (
Arabidopsis thaliana
) shows retarded growth, disordered chloroplast development, and delayed flowering time. In this study, we explored the possible connection between
Fe
availability and the circadian clock in growth and development. Circadian period length in Arabidopsis was longer under
Fe
-deficient conditions, but the lengthened period was not regulated by the canonical
Fe
-deficiency signaling pathway involving nitric oxide. However, plants with impaired chloroplast function showed long circadian periods.
Fe
deficiency and impaired chloroplast function combined did not show additive effects on the circadian period, which suggests that plastid-to-nucleus retrograde signaling is involved in the lengthening of circadian period under
Fe
deficiency. Expression pattern analyses of the central oscillator genes in mutants defective in
CIRCADIAN CLOCK ASSOCIATED1/LATE ELONGATED HYPOCOTYL
or
GIGANTEA
demonstrated their requirement for
Fe
deficiency-induced long circadian period. In conclusion,
Fe
is involved in maintaining the period length of circadian rhythm, possibly by acting on specific central oscillators through a retrograde signaling pathway.