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Science 19 December 2008:
Vol. 322. no. 5909, pp. 1832 - 1835
DOI: 10.1126/science.1161403
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Reports

The Circadian Clock in Arabidopsis Roots Is a Simplified Slave Version of the Clock in Shoots

Allan B. James1, José A. Monreal1, Gillian A. Nimmo1, Ciarán L. Kelly1, Pawel Herzyk2,3, Gareth I. Jenkins1 and Hugh G. Nimmo1*

1 Division of Molecular and Cellular Biology, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.
2 Division of Integrated Biology, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.
3 The Sir Henry Wellcome Functional Genomics Facility, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.


Figure 1 Fig. 1. TOC1 does not contribute to the root clock in constant light. (A and B) Gene expression in (A) LHY and (B) TOC1 was monitored over 24 hours in LD and then 72 hours in LL in Arabidopsis Col-0 by qPCR in shoots and roots. Estimates of period and the probability that the best-fit rhythm has a significant amplitude were made with COSOPT and are given in table S1. (C and D) LHY expression was monitored in (C) shoots and (D) roots in Arabidopsis Ws-0 and Arabidopsis toc1-10 by qPCR over 24 hours in LD and then 48 hours in LL. The levels of LHY transcripts in Ws-0 and toc1-10 were similar. Black bar, dark; white bars, light, day or subjective day; hatched bars, light, subjective night. [View Larger Version of this Image (46K GIF file)]
 

Figure 2 Fig. 2. Shoots, but not roots, contain an EE-binding protein expressed around dawn. (A) Specificity of the probe. Lane 1, labeled probe alone; lane 2, labeled probe plus shoot extract prepared at dawn; lane 3, as lane 2 plus unlabeled competitor probe; lane 4, as lane 2 plus unlabeled mutant competitor; lane 5, as lane 1 plus antiserum to LHY diluted 1:100; lane 6, as lane 1 plus antiserum to LHY diluted 1:1000; lane 7, as lane 2 plus antiserum to LHY diluted 1:100; lane 8, as lane 2 plus antiserum to LHY diluted 1:1000. (B) EE binding across a diurnal cycle. Shoot and root samples harvested at 3-hour intervals in an LD cycle were incubated with labeled probe. White bar, day; black bar, night. (C) LHY doublet bands (see also fig. S10) from shoot and root samples harvested at dawn and prepared for mobility shift analysis are shown by Western blotting. (D) Sequences of the probes: top, wild-type CAT3 EE probe, EE in bold; bottom, mutated probe, the altered bases are in lower case. [View Larger Version of this Image (49K GIF file)]
 

Figure 3 Fig. 3. The shoot and root clocks are synchronized in diurnal cycles. Gene expression in (A) LHY and (B) TOC1 was monitored over 45 hours in LD in Arabidopsis Col-0 by qPCR in shoots and roots. Black bars, dark; white bars, light. The data shown are from one representative experiment. Means and SEM from three replicate experiments are shown in fig. S13. [View Larger Version of this Image (27K GIF file)]
 

Figure 4 Fig. 4. Sucrose perturbs expression of clock genes in roots but not shoots. Gene expression in (A) TOC1, (B) CCA1, (C) PRR9, and (D) At1g78600 was monitored in Arabidopsis Col-0 by qPCR over 48 hours in LD, in LL, and in LD after addition of 2.5 mM sucrose to the hydroponic medium at dusk. Black bars, dark; white bars, light, day or subjective day; hatched bars, light, subjective night. The data shown are from one representative experiment. Means and SEM from three replicate experiments are shown in fig. S14. [View Larger Version of this Image (40K GIF file)]
 

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