Project description:This SuperSeries is composed of the following subset Series: GSE35057: Phytochrome Interacting Factor 4 and 5 regulate different set of genes in high and low red/far-red light GSE35059: ChIP-Seq analysis of Phytochrome Interacting Factor 5 DNA binding in low R/FR condition Refer to individual Series
Project description:Phytochromes are red/far red photosensors regulating numerous developmental programs in plants. Among them phytochrome A (phyA) is essential to enable seedling de-etiolation in continuous far-red (FR) light a condition mimicking the environment under a dense canopy. The ecological relevance of this response is demonstrated by the high mortality rate of phyA mutants germinating in deep vegetational shade. phyA signaling involves a direct interaction of the photoreceptor with members of the bHLH transcription factor family, PIF1 and PIF3 (Phytochrome Interacting Factor). Here we investigated the involvement of PIF4 and PIF5 in phyA signaling and found that they redundantly control de-etiolation in FR light. The pif4pif5 double mutant is hypersensitive to low fluence rates of FR light. This phenotype is dependent on FR light perception by phyA but does not rely on alterations of the phyA level. Our microarrays analysis shows that PIF4 and PIF5 are part of an inhibitory mechanism repressing the expression of some light-responsive genes in the dark and are also needed for full expression of several growth-related genes in the light. Unlike PIF1 and PIF3, PIF4 and PIF5 are not degraded in response to FR light indicating that they are light-regulated by a different mechanism. Our genetic analysis suggests that this is achieved through the sequestration of these PIFs by the closely related bHLH transcription factor HFR1 (long Hypocotyl in FR light). Experiment Overall Design: he pif4pif5 double mutant were compared to wild-type plants when kept in the dark or subjected to 1 or 24 hours of 0.5 or 5 µmol/m2/s far-red light respectively.
Project description:Phytochromes are red/far red photosensors regulating numerous developmental programs in plants. Among them phytochrome A (phyA) is essential to enable seedling de-etiolation in continuous far-red (FR) light a condition mimicking the environment under a dense canopy. The ecological relevance of this response is demonstrated by the high mortality rate of phyA mutants germinating in deep vegetational shade. phyA signaling involves a direct interaction of the photoreceptor with members of the bHLH transcription factor family, PIF1 and PIF3 (Phytochrome Interacting Factor). Here we investigated the involvement of PIF4 and PIF5 in phyA signaling and found that they redundantly control de-etiolation in FR light. The pif4pif5 double mutant is hypersensitive to low fluence rates of FR light. This phenotype is dependent on FR light perception by phyA but does not rely on alterations of the phyA level. Our microarrays analysis shows that PIF4 and PIF5 are part of an inhibitory mechanism repressing the expression of some light-responsive genes in the dark and are also needed for full expression of several growth-related genes in the light. Unlike PIF1 and PIF3, PIF4 and PIF5 are not degraded in response to FR light indicating that they are light-regulated by a different mechanism. Our genetic analysis suggests that this is achieved through the sequestration of these PIFs by the closely related bHLH transcription factor HFR1 (long Hypocotyl in FR light).
Project description:The absorption of visible light in aquatic environments has led to the common assumption that aquatic organisms sense and adapt to penetrative blue/green light wavelengths, but show little or no response to the more attenuated red/far-red wavelengths. Here we show that two marine diatom species, Phaeodactylum tricornutum and Thalassiosira pseudonana, possess a bona fide red/far-red light sensing phytochrome (DPH) that uses biliverdin as a chromophore and displays accentuated red-shifted absorbance peaks compared to other characterized plant and algal phytochromes. Exposure to both red and far-red light causes changes in gene expression in P. tricornutum and the responses to far-red light disappear in DPH knockout cells, demonstrating that P. tricornutum DPH mediates far-red light signaling. The identification of DPH genes in diverse diatom species widely distributed along the water column further emphasizes the ecological significance of far-red light sensing, raising questions about the sources of far-red light. Our analyses indicate that, although far-red wavelengths from sunlight are only detectable at the ocean surface, chlorophyll fluorescence and Raman scattering can generate red/far-red photons in deeper layers. This study opens up novel perspectives on phytochrome-mediated far-red light signaling in the ocean and on the light sensing and adaptive capabilities of marine phototrophs.
Project description:To identify and characterize genes required for tissue-specific phytochrome responses during hypocotyl development in far-red-light grown bvr lines, we performed gene transcriptional profiling using bvr lines with mesophyll-specific phytochrome inactivation (cab3: :pBVR2). We identified several candidate genes whose expression is significantly altered in lines with mesophyll tissue-specific BVR expression (Cab3::pBVR2), compared to constitutive phytochrome inactivation lines, i.e. 35S-driven BVR lines (35S::pBVR3). No-0 is used as wild-type (WT) Seeds of No-0 WT, 35S::pBVR3 and CAB3::pBVR2 on MS plates were exposed to Red (R) light of 75 M-BM-5mol m-2 s-1 for 5 min and imbibing seeds were cold-stratified at 4 M-BM-0C in darkness for 3 d. Seedlings were grown under continuous far-red illumination for 7 d. Seven-day-old vegetative whole seedlings (300 M-bM-^@M-^S 500 mg) were quickly (<1 min) harvested and immediately frozen in liquid nitrogen inside the FR chamber. Seedlings were grown under continuous far-red illumination for 7 d.
Project description:FAR-RED ELONGATED HYPOCOTYL 3 (FHY3) and its homolog FAR-RED IMPAIRED RESPONSE 1 (FAR1) are two transposase-derived transcription factors initially identified as the key components in phytochrome A signaling and recently shown to function in the circadian clock. However, whether FHY3 and FAR1 are involved in other processes of plant development remains largely unknown. Here, we explored chromatin immunoprecipitation-based sequencing (ChIP-seq) analysis to identify 1745 and 1171 FHY3 direct binding target genes in darkness and far-red light conditions, respectively in the Arabidopsis thaliana genome. This analysis revealed that FHY3 preferentially binds to the gene promoters through the previously identified typical FHY3/FAR1 binding motif. Interestingly, FHY3 also binds to two novel motifs in the 178-bp repeats of the Arabidopsis centromere regions in vivo. Comparison between the ChIP-seq and microarray data indicates that FHY3 regulates the expression of 196 and 85 genes in dark and far-red respectively by directly binding to their promoters. FHY3 also co-regulates a number of common target genes with PHYTOCHROME INTERACTING FACTOR 3-LIKE 5 (PIL5) and ELONGATED HYPOCOTYL 5 (HY5). Moreover, our genome-wide identification of FHY3 direct target genes ultimately led to the discovery and validation of a new role of FHY3 in controlling chloroplast development, by directly activating the expression of ACCUMULATION AND REPLICATION OF CHLOROPLASTS5 (ARC5), a key gene regulating chloroplast constriction and division. Taken together, our data suggest that FHY3 is involved in regulating multiple facets of plant development, thus providing new insights into the functions of this type of transposase-derived transcription factors.
Project description:FAR-RED ELONGATED HYPOCOTYL 3 (FHY3) and its homolog FAR-RED IMPAIRED RESPONSE 1 (FAR1) are two transposase-derived transcription factors initially identified as the key components in phytochrome A signaling and recently shown to function in the circadian clock. However, whether FHY3 and FAR1 are involved in other processes of plant development remains largely unknown. Here, we explored chromatin immunoprecipitation-based sequencing (ChIP-seq) analysis to identify 1745 and 1171 FHY3 direct binding target genes in darkness and far-red light conditions, respectively in the Arabidopsis thaliana genome. This analysis revealed that FHY3 preferentially binds to the gene promoters through the previously identified typical FHY3/FAR1 binding motif. Interestingly, FHY3 also binds to two novel motifs in the 178-bp repeats of the Arabidopsis centromere regions in vivo. Comparison between the ChIP-seq and microarray data indicates that FHY3 regulates the expression of 196 and 85 genes in dark and far-red respectively by directly binding to their promoters. FHY3 also co-regulates a number of common target genes with PHYTOCHROME INTERACTING FACTOR 3-LIKE 5 (PIL5) and ELONGATED HYPOCOTYL 5 (HY5). Moreover, our genome-wide identification of FHY3 direct target genes ultimately led to the discovery and validation of a new role of FHY3 in controlling chloroplast development, by directly activating the expression of ACCUMULATION AND REPLICATION OF CHLOROPLASTS5 (ARC5), a key gene regulating chloroplast constriction and division. Taken together, our data suggest that FHY3 is involved in regulating multiple facets of plant development, thus providing new insights into the functions of this type of transposase-derived transcription factors.
Project description:To identify and characterize genes required for tissue-specific phytochrome responses during hypocotyl development in far-red-light grown bvr lines, we performed gene transcriptional profiling using bvr lines with mesophyll-specific phytochrome inactivation (cab3: :pBVR2). We identified several candidate genes whose expression is significantly altered in lines with mesophyll tissue-specific BVR expression (Cab3::pBVR2), compared to constitutive phytochrome inactivation lines, i.e. 35S-driven BVR lines (35S::pBVR3). No-0 is used as wild-type (WT)