Project description:DE-ETIOLATED1 (DET1) is a negative regulator of plant photomorphogenesis acting as a component of the C3D complex, which can further associate to CULLIN4 to form a CRL4C3D E3 ubiquitin ligase. CRL4C3D is thought to act together with CRL4COP1SPA ubiquitin ligase, to promote the ubiquitin-mediated degradation of the master regulatory transcription factor ELONGATED HYPOCOTYL5 (HY5), thereby controlling photomorphogenic gene regulatory networks. Yet, functional links between COP1 and DET1 have long remained elusive. Here, upon mass spectrometry identification of DET1 and COP1-associated proteins, we provide in vivo evidence that DET1 associates with COP1 to promote its destabilization, a process necessary to dampen HY5 protein abundance. By regulating HY5 over-accumulation, DET1 is critical to avoid its association to second-site loci, including many PIF3 target genes. Accordingly, excessive HY5 levels result in an increased HY5 repressive activity and are sufficient to trigger fusca-like phenotypes otherwise observed typically in COP1 and COP9 signalosome mutant seedlings. This study therefore identifies that DET1-mediated regulation of COP1 stability tunes down HY5 cistrome and avoids hyper-photomorphogenic responses that might compromise plant viability.
Project description:Characterization of RCI1A role in the control of the response to low temperature of cold induced genes. Two-condition experiment, rci1a vs. WT plants. Biological replicates: 3 aclimated and 3 control replicates.
Project description:Autophagy, involved in protein degradation and amino acid recycling, plays a key role in plant development and stress responses. However, the relationship between autophagy and phytohormones is unclear. We used diverse methods, including CRISPR/Cas9, UPLC-MS/MS, chromatin immunoprecipitation, electrophoretic mobility shift assays, and dual-luciferase assays to explore the molecular mechanism of strigolactones in regulating autophagy and the degradation of ubiquitinated proteins under cold stress in tomato. We show that cold stress induced the accumulation of ubiquitinated proteins. Mutants deficient in strigolactone biosynthesis were more sensitive to cold stress with a higher accumulation of ubiquitinated proteins, while treatment with the synthetic strigolactone analog GR245DS enhanced cold tolerance in tomato, with a higher accumulation of autophagosomes and transcripts of autophagy-related genes (ATGs), and a lower accumulation of ubiquitinated proteins. Meanwhile, cold stress induced ELONGATED HYPOCOTYL 5 (HY5) accumulation, which was triggered by strigolactones. HY5 further trans-activated ATG18a promoter, resulting in autophagy formation. Mutation of ATG18a compromised strigolactone-induced cold tolerance, followed by a decreased formation of autophagosomes and an increased accumulation of ubiquitinated proteins. These findings reveal that strigolactones positively regulate autophagy in an HY5-dependent manner and promote the degradation of ubiquitinated proteins under cold conditions in tomato.
Project description:As a source of both energy and environmental information, the importance for plants to monitor the incoming light is evidenced by the highly integrated nature of the light signal transduction pathway with numerous other pathways throughout plant development. One of these signal integrators is the bZIP transcription factor HY5 which holds a key role as a positive regulator of light signalling in plants. Although HY5 is described to act as a DNA-binding transcriptional regulator, the lack of any apparent transactivation domain makes it unclear how HY5 is able to accomplish its many functions. We describe the identification of three B-box containing proteins (BBX20, 21 and 22) as essential partners for HY5 dependent modulation of hypocotyl elongation, anthocyanin accumulation and transcriptional regulation. The bbx202122 triple mutant mimics the phenotypes of hy5 in the light and its strong suppression of the cop1 phenotype in darkness. Furthermore, RNA-seq experiments show that 84% of genes differentially regulated in bbx202122 are also HY5 regulated, consistent with the B-box proteins and HY5 acting interdependently.
Project description:We show that longer-term inhibition of shade avoidance in Arabidopsis is sustained by ELONGATED HYPOCOTYL 5 (HY5) and HY5 HOMOLOG (HYH) which, together, regulate transcriptional reprogramming of genes involved in hormone signalling and cell wall modification.
Project description:The transcription factor HY5 acts downstream of multiple families of the photoreceptors and promotes photomorphogenesis. Although it is well accepted that HY5 acts to regulate target gene expression, in vivo binding of HY5 to any of its target gene promoters has yet to be demonstrated. Here we used a chromatin immunoprecipitation procedure to verify suspected in vivo HY5 binding sites. We demonstrated that in vivo association of HY5 with promoter targets is not altered under distinct light qualities or during light-to-dark transition. Coupled with DNA chip hybridization using high density 60-nucleotide oligomer microarray that contains one probe for every 500 nucleotides over the entire Arabidopsis genome, we mapped genome wide in vivo HY5 binding sites. This analysis showed that HY5 binds preferentially to promoter regions in vivo and revealed over 3 thousand chromosomal sites as putative HY5 binding targets. HY5 binding targets tend to be enriched in the early light responsive genes and transcription factor genes. Our data thus supports a model in which HY5 is a high hierarchical regulator of the transcriptional cascades for photomorphogenesis. Keywords: ChIP-chip
Project description:Gene expression profiles between wild type (WT) and hy5 were compared to know HY5-targets. Gene expression profiles between wild type (WT) and hy5 were compared to known HY5-targets.
Project description:Analysis of gene expression level. The hypothesis tested in the present study was that hy5 mutant affects multiple genes expression which regulated by COR27 and COR28