Project description:Analysis of etiolated seedlings exposed for 1hr to red light. Phytochromes are red/far-red light receptors, palying important roles in photomorphogenesis. Results suggest that red light and phytochromes regulate a set of genes' expression in seedlings.
Project description:phytochrome B (phyB) acts as the red light photoreceptor and negatively regulates the growth-promoting factor PHYTOCHROME INTERACTING 4 (PIF4) through a direct physical interaction, which in turn changes the expression of a large number of genes. phyB-PIF4 module regulates a variety of biological and developmental processes in plants. In this study, we demonstrate that B-BOX PROTEIN 11 (BBX11) physically interacts with both phyB and PIF4. BBX11 negatively regulates PIF4 accumulation as well as its biochemical activity, consequently leading to the repression of PIF4-controlled genes' expression and promotion of photomorphogenesis in the prolonged red light. This study reveals a regulatory mechanism that mediates red light signal transduction and sheds a light on phyB-PIF4 module in promoting red light-dependent photomorphognenesis.
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:Light and microRNAs (miRNAs) are key external and internal signals for plant development respectively. However the relationship between light signaling and miRNA biogenesis pathways remains unknown. Here we found that miRNA processer DCL1/HYL1 interacts with a basic helix–loop–helix (bHLH) transcription factor, phytochrome-interacting factor 4 (PIF4), which mediates the destabilization of DCL1 during dark-red light transition. PIF4 acts as a transcription factor for some miRNA genes and is necessary for the proper accumulation of miRNAs. DCL1/HYL1 and mature miRNAs play roles in the regulation of plant hypocotyl growth. These results uncovered a previously unknown crosstalk between miRNA biogenesis and red light signaling through the PIF4-dependent regulation of miRNA transcription and processing to affect red light-directed plant photomorhogenesis.
Project description:PIL5 is a key negative regulator of phytochrome mediated seed germination and PIL5 protein is degraded by red light irradiation through phytochrome. The microarray aimed to find various red light-regulated genes and PIL5-regulated genes in the imbibed seeds. Keywords: genetic modification
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. 4 samples, dark-grown wild-type and pubs hy2 protonema as time 0 control, followed by red light irradiation for one hour 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:Light is an ever-changing environmental parameter affecting almost every aspects of plant growth and development. It is perceived by photoreceptors, among them phytochromes (PHY) are responsible for monitoring the red and far-red part of the spectrum. Arabidopsis thaliana possesses five phytochromes genes, named through phyA-phyE. Whereas the function of phyA and phyB – that mediate most of the phytochrome responses – is extensively studied, our knowledge on other phytochromes are still rudimentary. To analyze phyD function we expressed it at high levels in different phytochrome deficient genetic backgrounds. We found that overexpressed phyD governs effective light signaling at low temperatures but only in cooperation with functional phyC. Under these conditions, opposite to phyB, phyD accumulates to high levels and this pool is stable under light illumination. Furthermore, the detectable photoconvertible phyD amount is proportional with the available protein amount indicating that the phyD pool contains fully functional photoreceptors. The thermal reversion of phyD is very fast suggesting that the thermosensing of phyD is based on its protein amount and not on its Pfr conformer stability, which was described for phyB. We also found that phyD and phyB associate to identical genomic locations and mediate similar gene expression changes, however the efficiency of phyD is lower. Taken together our data suggest that under certain conditions synergistic interaction of phyD and phyC substitutes phyB function thus increases the ability of plants to respond more flexible to environmental changes.
Project description:Light is an ever-changing environmental parameter affecting almost every aspects of plant growth and development. It is perceived by photoreceptors, among them phytochromes (PHY) are responsible for monitoring the red and far-red part of the spectrum. Arabidopsis thaliana possesses five phytochromes genes, named through phyA-phyE. Whereas the function of phyA and phyB – that mediate most of the phytochrome responses – is extensively studied, our knowledge on other phytochromes are still rudimentary. To analyze phyD function we expressed it at high levels in different phytochrome deficient genetic backgrounds. We found that overexpressed phyD governs effective light signaling at low temperatures but only in cooperation with functional phyC. Under these conditions, opposite to phyB, phyD accumulates to high levels and this pool is stable under light illumination. Furthermore, the detectable photoconvertible phyD amount is proportional with the available protein amount indicating that the phyD pool contains fully functional photoreceptors. The thermal reversion of phyD is very fast suggesting that the thermosensing of phyD is based on its protein amount and not on its Pfr conformer stability, which was described for phyB. We also found that phyD and phyB associate to identical genomic locations and mediate similar gene expression changes, however the efficiency of phyD is lower. Taken together our data suggest that under certain conditions synergistic interaction of phyD and phyC substitutes phyB function thus increases the ability of plants to respond more flexible to environmental changes.