Project description:We generated 18 Gb of high-quality sequencing data (~3 Gb per sample) and catalogued the expression profiles of 27,416 annotated Arabidopsis thaliana genes in each sample. The analysis showed differences of transcriptomes between wild-type Col and Nuclear Factor Y (NF-Y) C1,3,4,9 loss of function mutant nf-yc quadruple (nf-ycQ) seedlings treated with 2 days red light. We identified numerous differentially expressed genes that exhibited distinct expression patterns. These genes have known or potential roles in growth and development of Arabidopsis thaliana. Therefore, they are appealing candidates for further investigation of the gene expression and associated regulatory mechanisms related to NF-YCs in light signaling pathway.
Project description:Jasmonates are key regulators of the balance between defence and growth in plants. However, the molecular mechanisms by which activation of defences reduces growth are not yet understood. Here, we analyze the role of MYC transcription factors (TFs) and JA in photomorphogenic growth. We found that multiple myc mutants share light-related phenotypes with mutants of the phytochrome B photoreceptor, regarding seed germination and hypocotyl growth. Over-expression of MYC2 in a phyB background partially suppressed its long hypocotyl phenotype. We show that the activity of MYC TFs is partially independent of COI1 and that JA inhibition of hypocotyl growth acts through alteration of auxin homeostasis and is partially independent of the classical JA signalling pathway. Transcriptomic analysis of multiple myc mutants confirmed that MYCs are required for full expression of R-light regulated genes, including the master regulator HY5. ChIP-Seq analyses revealed that MYC2 and MYC3 directly bind to the promoter of HY5 and that HY5 gene expression and protein levels are compromised in multiple myc mutants. Moreover, MYC2 and MYC3 share a high amount of direct targets with PIFs, and have an opposite effect on gene expression of these targets. Altogether, our results pinpoint MYCs as photomorphogenic TFs that regulate phytochrome responses by regulating PIFs targets and activating HY5 expression. This has important implication to understand the trade-off between growth and defence, since the same TFs that activate defence responses are photomorphogenic growth regulators.
Project description:Nuclear Factor Y (NF-Y) is a heterotrimeric transcription factor that binds CCAAT elements. The NF-Y trimer is composed of a Histone Fold Domain (HFD) dimer (NF-YB/NF-YC) and NF-YA, which confers DNA sequence specificity. NF-YA shares a conserved domain with the CONSTANS, CONSTANS-LIKE, TOC1 (CCT) proteins. We show that CONSTANS (CO/B-BOX PROTEIN1 BBX1), a master flowering regulator, forms a trimer with Arabidopsis thaliana NF-YB2/NF-YC3 to efficiently bind the CORE element of the FLOWERING LOCUS T promoter. Using saturation mutagenesis, electrophoretic mobility shift assays, and RNA-sequencing profiling of co, nf-yb, and nf-yc mutants, we identify CCACA elements as the core NF-CO binding site. CO physically interacts with the same HFD surface required for NF-YA association, as determined by mutations in NF-YB2 and NF-YC9, and tested in vitro and in vivo. The co-7 mutation in the CCT domain, corresponding to an NF-YA arginine directly involved in CCAAT recognition, abolishes NF-CO binding to DNA
Project description:Five members of the Arabidopsis thaliana NF-YA gene family are strongly induced by several stress conditions via transcriptional and miR169-related posttranscriptional mechanisms. These transcription factors participate in gene regulation via two different mechanisms, one depending on binding to the CCAAT-box in the promoter of regulated genes and the other, independent of the CCAAT-box, in which NF-YA prevents the interaction of the NF-YB/YC heterodimer with transcription factors.
Project description:Injured plant somatic tissues regenerate themselves by establishing the shoot or root meristems. In Arabidopsis (Arabidopsis thaliana) a two-step culture system ensures regeneration by first promoting the acquisition of pluripotency and subsequently specifying the fate of new meristems. Although previous studies have reported the importance of phytohormones auxin and cytokinin in determining the fate of new meristems, it remains elusive whether and how the environmental factors influence this process. In this study, we investigated the impact of light signals on shoot regeneration using Arabidopsis hypocotyl as explants. We found that light signals promote shoot regeneration while inhibiting root formation. ELONGATED HYPOCOTYL 5 (HY5), the pivotal transcriptional factor in light signaling, plays a central role in this process by mediating the expression of key genes controlling the fate of new meristems. Specifically, HY5 directly represses root development genes and activates shoot meristem genes, leading to the establishment of shoot progenitor from pluripotent callus. We further demonstrated that the early activation of photosynthesis is critical for shoot initiation, and this is transcriptionally regulated downstream of the HY5-dependent pathways. In conclusion, we uncovered the intricate molecular mechanisms by which light signals control the establishment of new meristem through the regulatory network governed by HY5, thus, highlighting the influence of light signals on plant developmental plasticity.
Project description:Five members of the Arabidopsis thaliana NF-YA gene family are strongly induced by several stress conditions via transcriptional and miR169-related posttranscriptional mechanisms. These transcription factors participate in gene regulation via two different mechanisms, one depending on binding to the CCAAT-box in the promoter of regulated genes and the other, independent of the CCAAT-box, in which NF-YA prevents the interaction of the NF-YB/YC heterodimer with transcription factors. Three biological and two technical (in swap) replicates for each genotype were obtained for each treatment (DMSO (mock) and estradiol 24h after induction). Mock samples were pooled and used as a reference.
Project description:We work with Arabidopsis thaliana. One of the things we focus on is a secondary metabolite named Indol 3 carbinol (I3C). This molecule is synthesized following insect attack (wounding). We have noticed that addition of I3C to the growth medium causes inhibition of plant/bacterial/fungal growth. We have discovered that I3C also affects different pathways in the plant. By screening overexpression library we have found Arabidopsis mutants that overexpress S30 gene (ribosomal subunit of 40s) are tolerant to the addition of I3C (their growth is less affected by the addition of I3C). To understand better I3C mode of action we have planned the following transcriptome experiment: 1. To see what are the pathways activated following wounding, we took the wt Arabidopsis thaliana (Col-0) and kept one group of plants untreated (control) and the other was wounded (8 hours). 2. To see what are the pathways activated following incubation with 2 concentrations of I3C, we took the wt Arabidopsis thaliana (Col-0) and kept one group of plants untreated (control) and the other was incubated for 2 hours with 200µM (physiological concentration) and 400µM I3C. 3. To see if there are any differences in gene expression between the wt and the mutants, we took wt and 2 I3C tolerant mutants. Neither of them was treated. 4. To see if in the mutant other pathways are activated following incubation with I3C, both mutants were incubated in I3C. In all cases we have used the roots only for RNA extraction.