Project description:The red-light regulated transcription factors FHY3 and FAR1 form a key point of light input to the plant circadian clock in positively regulating expression of genes within the central clock. However, the fhy3 mutant shows an additional red light-specific disruption of rhythmicity which is inconsistent with this role. Here we demonstrate that only fhy3 and not far1 mutants show this red specific disruption of rhythmicity. We examined the differences in rhythmic transcriptome in red versus white light and reveal differences in patterns of rhythmicity among the central clock proteins suggestive of a change in emphasis withing the central mechanism of the clock, changes which underlie the red specificity of the fhy3 mutant. In particular, changes in enrichment of promoter elements were consistent with a key role for the HY5 transcription factor, a known integrator of the ratio of red to blue light in regulation of the clock. Examination of differences in the rhythmic transcriptome in the fhy3 mutant in red light which identified specific disruption of the CCA1-regulated ELF3 and LUX central clock genes, while the CCA1 target TBS element, TGGGCC, was enriched among genes that became arrhythmic. Coupled with the known interaction of FHY3 but not FAR1 with CCA1 we propose that the red-specific circadian phenotype of fhy3 may involve disruption of the previously-demonstrated moderation of CCA1 activity by FHY3 rather than a disruption of its own transcriptional regulatory activity. Together, this evidence suggests a conditional redundancy between FHY3 and HY5 in the integration of red and blue light input to the clock in order to enable a plasticity in response to light and optimise plant adaptation. Furthermore, our evidence also suggests changes in CCA1 activity between red and white light transcriptomes. This, together with the documented interaction of HY5 with CCA1, leads us to propose a model whereby this integration of red and blue signals may at least partly occur via direct FHY3 and HY5 interaction with CCA1 leading to moderation of CCA1 activity.
Project description:To study the transcriptomic profile of wt and brc1 mutant axillary buds during the shade avoidance response, we simulated a canopy shade with a low R/FR light ratio. We treated plants with white light supplemented with far-red light (Red light = 29 μeinstein · m-2 seg-1, Far-Red light= 146 μeinstein · m-2 seg-1) for 8 hours. Control plants were left for 8 hours in white light (Red light = 29 μeinstein · m-2 seg-1, Far-Red light= 2.2 μeinstein · m-2 seg-1) .
Project description:Light initiates the seedling deetiolation transition by promoting major changes in gene expression mainly regulated by phytochrome (phy) photoreceptors. During the initial dark-to-light transition, phy photoactivation induces rapid changes in gene expression that eventually lead to the photomorphogenic development. Recent reports indicate that this process is achieved by phy-induced degradation of Phy-Interacting bHLH transcription Factors (PIFs) PIF1, PIF3 PIF4 and PIF5, which are partly redundant constitutive repressors of photomorphogenesis that accumulate in darkness. In order to test whether light/phy-regulated gene expression occurs through these PIFs, we have performed whole-genome expression analysis in the pif1pif3pif4pif5 quadruple mutant (pifq). Wild-type and pifq mutant seeds were plated on GM medium without sucrose at room temperature. During this procedure the seeds were routinely exposed to white light (WL) for a total of 1.5 hours after imbibition. Seeds were then stratified for 5 days at 4ºC in darkness, induced to germinate with a 5-min red pulse (Rp) (46 μmol/m2/s) and then incubated in the dark for 3h at 21°C before exposure to a terminal 5-min far red pulse (FRp) (58 μmol/m2/s) to suppress pseudo-dark effects. Seeds were then placed in either dark (D) or constant red light (Rc) (6.7 μmol/ m2/s) at 21°C for 45h (2d-old seedlings). Alternatively, 2d-old dark-grown seedlings were treated with 1h of red light (R1) (7.5 μmol/m2/s). Seed samples were harvested after stratification (5d stratified seeds).
Project description:Phytochromes are red/far-red light photoreceptors. We sought to test at the transcriptomic level if Arabidopsis mutants lacking all phytochromes (from phyA to phyE), or just retaining trace levels of phyC, had transcriptional response to red light exposure. phyABCDE and phyABDE mutants were grown for 4 days in darkness (D), or under continuous red light at 50 µmol m-2 s-1 (R50), or in darkness followed by 2 hr of red light exposure on day 4 (DR2h). Differentially expressed genes of the mutants in response to red light were compared to those of wild type obtained previously {Hu et al. (2009) Molecular Plant, 2: 166-182}. Three biological replicates were employed for dark and Rc-grown samples, and 2 biological replicates for DR2h samples, thus 8 samples were used for each mutant genotype. It needs to be pointed out that 5 of the 6 WT samples (from WT-D-2 to WT-R50-2) had previously been deposited with GEO accessions GSM226267, GSM226268, GSM226269, GSM226278 and GSM226279. Their cRNA samples were synthesized and labeled with the Affymetrix GeneChip® Expression Analysis kits (One-cycle target labeling and control reagents). They are included in this series of study for convenient comparison, with newly assigned accessions from GSM784837 to GSM784841. The more recent GeneChip 3' IVT Express Kit (Affymetrix) was used to synthesize and label aRNA for one new WT sample (WT-D-1)(GSM784836) and all mutant samples.
Project description:To study the transcriptomic profile of wt and brc1 mutant axillary buds during the shade avoidance response, we simulated a canopy shade with a low R/FR light ratio. We treated plants with white light supplemented with far-red light (Red light = 29 μeinstein · m-2 seg-1, Far-Red light= 146 μeinstein · m-2 seg-1) for 8 hours. Control plants were left for 8 hours in white light (Red light = 29 μeinstein · m-2 seg-1, Far-Red light= 2.2 μeinstein · m-2 seg-1) . Six biological replicates of 7-8 plants were collected for each genotype and condition (wt WL, wt FR, brc1 WL, brc1 FR). Samples were compared wt WL vs wt FR and brc1 WL vs brc1 FR.
Project description:Light, as both energy source and informational signal, profoundly influences plant growth and development during the whole life span from seed germination to flowering. To dissect the role for red light signaling in regulate the seedling development, we analyzed the gene expression profile of red light- and dark-grown WT seedlings by high throughput sequencing.
Project description:The hemera (hmr) mutant was identified as the first photomorphogenetic mutant with the combination of long hypocotyl and albino phenotypes in the light. Phytochrome-Interacting bHLH transcription Factors (PIFs), which are repressors of photomorphogenesis accumulate in darkness and are degraded in the light in a phytochrome-dependent manner. Two PIFs, PIF1 and PIF3 accumulated in the light in hmr mutants. In order to determine the gene expression of PIF-dependent genes in hmr mutants in the light, we have performed whole-genome expression analysis on two hmr mutants: a null allele, hmr-5; and a weak allele, hmr-22. Wild-type (Col-0) and hmr mutant seeds were surface-sterilized and plated on half-strength Murashige and Skoog (MS) growth medium without sucrose. The seeds were stratified in the dark at 4ºC for 4d. Seedlings were grown in constant red light (Rc, 10?mol/m2/s) at 21°C for 4d.
Project description:The red/far-red light photoreceptor phytochrome mediates photomorphological responses in plants. For light sensing and signaling, phytochromes need to associate with open-chain tetrapyrrole molecules as the chromophore. Biosynthesis of tetrapyrrole chromophores requires members of ferredoxin-dependent bilin reductases (FDBRs). There are two FDBRs in Physcomitrella patens, HY2 and PUBS. Knocking out both generates the phytochrome-deficient mutant. Datasets here provides the transcriptome profiling of Physcomitrella protonema grown in the dark and exposed to one hour red light. Wild type and the hy2 pubs double mutant were used to dissect the regulated genes of moss phytochromes. For details, please see PMID: .
Project description:The mRNA expression profiles of the wild type, phyB and phyAB mutants were analyzed with darkness or 1 hour red light treatment. Results provide insight into the role of red-light and phytochromes in gene expression.
Project description:Phytochromes are red/far-red light photoreceptors. We sought to test at the transcriptomic level if Arabidopsis mutants lacking all phytochromes (from phyA to phyE), or just retaining trace levels of phyC, had transcriptional response to red light exposure.