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- Johansson, Mikael, 1981-, et al.
(författare)
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Partners in time : early bird associates with zeitlupe and regulates the speed of the arabidopsis clock
- 2011
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Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 0032-0889 .- 1532-2548. ; 155:4, s. 2108-2122
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Tidskriftsartikel (refereegranskat)abstract
- The circadian clock of the model plant Arabidopsis (Arabidopsis thaliana) is made up of a complex series of interacting feedback loops whereby proteins regulate their own expression across day and night. early bird (ebi) is a circadian mutation that causes the clock to speed up: ebi plants have short circadian periods, early phase of clock gene expression, and are early flowering. We show that EBI associates with ZEITLUPE (ZTL), known to act in the plant clock as a posttranslational mediator of protein degradation. However, EBI is not degraded by its interaction with ZTL. Instead, ZTL counteracts the effect of EBI during the day and increases it at night, modulating the expression of key circadian components. The partnership of EBI with ZTL reveals a novel mechanism involved in controlling the complex transcription-translation feedback loops of the clock. This work highlights the importance of cross talk between the ubiquitination pathway and transcriptional control for regulation of the plant clock.
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- Johansson, Mikael, et al.
(författare)
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Partners in time: EARLY BIRD reveals novel regulatory function of ZEITLUPE in the Arabidopsis clock
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The circadian clock of the model plant Arabidopsis thaliana is made up of acomplex series of interacting feedback loops whereby proteins regulate their ownexpression across day and night. early bird (ebi) is a circadian mutation that causesthe clock to speed up: ebi plants have short circadian periods, early phase of clockgene expression and are early flowering. We show that EBI associates with ZEITLUPE (ZTL), known to act in the plant clock as a post-translational mediator of protein degradation. However, EBI is not degraded by its interaction with ZTL. Instead, EBI acts in opposition to ZTL, modulating the expression of key circadiancomponents. The partnership of EBI with ZTL reveals a novel mechanism involved incontrolling the complex transcription-translation feedback loops of the clock. Thiswork highlights the importance of cross-talk between the ubiquitination pathway andtranscriptional control for regulation of the plant clock
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- Ashelford, Kevin, et al.
(författare)
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Full genome re-sequencing reveals a novel circadian clock mutationin Arabidopsis
- 2011
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Ingår i: Genome Biology. - : Springer Science and Business Media LLC. - 1465-6906 .- 1474-760X. ; 12, s. R28-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Map based cloning in Arabidopsis thaliana can be a difficult and time-consuming process,specifically if the phenotype is subtle and scoring labour intensive. An alternative to map basedcloning would be to directly sequence the whole genome of a mutant to uncover the mutationresponsible for the phenotype. Results: Here, we have re-sequenced the 120 Mb genome of a novel Arabidopsis clock mutant earlybird (ebi-1), using massively parallel sequencing by ligation. This process was further complicated by the fact that ebi-1 is in Wassilewskija (Ws-2), not the reference accession ofArabidopsis. The approach reveals evidence of DNA strand bias in the ethyl methanesulfonate(EMS) mutation process. We have demonstrated the utility of sequencing a backcrossed line andusing gene expression data to limit the number of SNP considered. Using new SNP informationwe have excluded a previously identified clock gene, PRR7. Finally, we have identified a SNPin the gene AtNFXL-2 as the likely cause of the ebi-1 phenotype and validated this bycharacterising a further allele. Conclusion: In Arabidopsis, as in other organisms, the (EMS) mutation load can be high. Here wedescribe how sequencing a backcrossed line, using functional genomics and analysing new SNPinformation can be used to reduce the number EMS mutations for consideration. Moreover, theapproach we describe here does not require out-crossing and scoring F2 mapping populations, anapproach which can be compromised by background effects. The strategy has broad utility andwill be an extremely useful tool to identify causative SNP in other organisms.
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- Edwards, Kieron D., et al.
(författare)
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Circadian clock components control daily growth activities by modulating cytokinin levels and cell division-associated gene expression in Populus trees
- 2018
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Ingår i: Plant, Cell and Environment. - : John Wiley & Sons. - 0140-7791 .- 1365-3040. ; 41:6, s. 1468-1482
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Tidskriftsartikel (refereegranskat)abstract
- Trees are carbon dioxide sinks and major producers of terrestrial biomass with distinct seasonal growth patterns. Circadian clocks enable the coordination of physiological and biochemical temporal activities, optimally regulating multiple traits including growth. To dissect the clock's role in growth, we analysed Populus tremula x P. tremuloides trees with impaired clock function due to down-regulation of central clock components. late elongated hypocotyl (lhy-10) trees, in which expression of LHY1 and LHY2 is reduced by RNAi, have a short free-running period and show disrupted temporal regulation of gene expression and reduced growth, producing 30-40% less biomass than wild-type trees. Genes important in growth regulation were expressed with an earlier phase in lhy-10, and CYCLIN D3 expression was misaligned and arrhythmic. Levels of cytokinins were lower in lhy-10 trees, which also showed a change in the time of peak expression of genes associated with cell division and growth. However, auxin levels were not altered in lhy-10 trees, and the size of the lignification zone in the stem showed a relative increase. The reduced growth rate and anatomical features of lhy-10 trees were mainly caused by misregulation of cell division, which may have resulted from impaired clock function.
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- Kevei, Eva, et al.
(författare)
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Forward genetic analysis of the circadian clock separates the multiple functions of ZEITLUPE.
- 2006
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Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 0032-0889 .- 1532-2548. ; 140:3, s. 933-45
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Tidskriftsartikel (refereegranskat)abstract
- The circadian system of Arabidopsis (Arabidopsis thaliana) includes feedback loops of gene regulation that generate 24-h oscillations. Components of these loops remain to be identified; none of the known components is completely understood, including ZEITLUPE (ZTL), a gene implicated in regulated protein degradation. ztl mutations affect both circadian and developmental responses to red light, possibly through ZTL interaction with PHYTOCHROME B (PHYB). We conducted a large-scale genetic screen that identified additional clock-affecting loci. Other mutants recovered include 11 new ztl alleles encompassing mutations in each of the ZTL protein domains. Each mutation lengthened the circadian period, even in dark-grown seedlings entrained to temperature cycles. A mutation of the LIGHT, OXYGEN, VOLTAGE (LOV)/Period-ARNT-Sim (PAS) domain was unique in retaining wild-type responses to red light both for the circadian period and for control of hypocotyl elongation. This uncoupling of ztl phenotypes indicates that interactions of ZTL protein with multiple factors must be disrupted to generate the full ztl mutant phenotype. Protein interaction assays showed that the ztl mutant phenotypes were not fully explained by impaired interactions with previously described partner proteins Arabidopsis S-phase kinase-related protein 1, TIMING OF CAB EXPRESSION 1, and PHYB. Interaction with PHYB was unaffected by mutation of any ZTL domain. Mutation of the kelch repeat domain affected protein binding at both the LOV/PAS and the F-box domains, indicating that interaction among ZTL domains leads to the strong phenotypes of kelch mutations. Forward genetics continues to provide insight regarding both known and newly discovered components of the circadian system, although current approaches have saturated mutations at some loci.
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