title: The circadian clock modulates water dynamics and aquaporin expression in Arabidopsis roots.
abstract: We have developed a plant growth system to analyze water dynamics in the roots of a small model plant, Arabidopsis thaliana, by nuclear magnetic resonance (NMR) microscopic imaging. Using the two-dimensional slice technique, we obtained a series of images with high signal-to-noise ratio indicating the water distribution in the root. To demonstrate light regulation of water transport in the root and involvement of aquaporin gene expression, we visualized the distribution of water in Arabidopsis roots under various light conditions and compared the data with the expression profiles of two aquaporin genes. (1)H-NMR imaging revealed that water content in Arabidopsis roots is lower in the light than in the dark. This diurnal variation in water content was clearly observed in the basal zone of the root. In addition, an autonomous rhythm of water dynamics was observed under continuous light (LL) and darkness (DD). However, the circadian oscillation in water dynamics was obscured in the early-flowering 3 (elf3) mutant under LL. The expression of both the aquaporin genes, AtPIP1;2 and AtPIP2;1, oscillated with the circadian rhythm under LL conditions in wild-type seedlings, but not in the elf3 mutant. These results demonstrate the advantages of our technique for monitoring water dynamics in roots of living Arabidopsis seedlings, and suggest that the circadian clock modulates water dynamics and aquaporin expression.
authors.affiliation: Laboratory for Photobiology, Photodynamics Research Center, RIKEN, 519-1399 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi, 980-0845 Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Takase
authors.forename: Haruki
authors.initials: H
authors.lastname: Ishikawa
authors.forename: Haruko
authors.initials: H
authors.lastname: Murakami
authors.forename: Jun
authors.initials: J
authors.lastname: Kikuchi
authors.forename: Kumi
authors.initials: K
authors.lastname: Sato-Nara
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Suzuki
mesh_terms: D020346:Aquaporins / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism / Q000502:physiology* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D057906:Circadian Clocks; D018506:Gene Expression Regulation, Plant; D008027:Light; D009682:Magnetic Resonance Spectroscopy; D018517:Plant Roots / Q000378:metabolism / Q000502:physiology; D018749:RNA, Plant / Q000235:genetics; D014867:Water / Q000378:metabolism*
chemical_list: D020346:Aquaporins; D029681:Arabidopsis Proteins; D018749:RNA, Plant; D014867:Water