Project description:The cold acclimation process is regulated by many factors like ambient temperature, day length, light intensity, or hormonal status. Experiments with plants grown under different light-quality conditions indicate that the plant response to cold is also a light-quality-dependent process. Here, the role of light quality in the cold response was studied in one-month-old Arabidopsis thaliana (Col‐0) plants exposed for one week to 4 °C at short‐day conditions under white (100 and 20 μmol m‐2s‐1), blue or red (20 μmol m‐2s‐1) light conditions. An upregulated expression of CBF1, an inhibition of photosynthesis, and an increase in membrane damage showed that blue light enhanced the effect of low temperature. Interestingly, cold-treated plants under blue and red light showed only limited freezing tolerance compared to white light cold-treated plants. Next, the specificity of the light quality signal in cold response was evaluated in Arabidopsis accessions originating from different and contrasting latitudes. In all but one Arabidopsis accessions, blue light increased the effect of cold on photosynthetic parameters and electrolyte leakage. This effect was not found for Ws-0, which lacks functional CRY2 protein, indicating its role in the cold response. Proteomics data confirmed significant differences between red and blue light treated plants at low temperature and showed that the cold response is highly accession specific. In general, blue light increased mainly the cold-stress related proteins and red light induced higher expression of chloroplast-related proteins, which correlated with higher photosynthetic parameters in red light cold-treated plants. Altogether, our data suggest that light modulates two distinct mechanisms during the cold treatment - red light driven cell function maintaining program and blue light activated specific cold response. The importance of mutual complementarity of these mechanisms was demonstrated by significantly higher freezing tolerance of cold-treated plants under white light.
Project description:Elongator is a histone acetyltransferase (HAT) complex associated with RNA polymerase II (RNAPII) to facilitate transcription elongation. It consists of subunits Elp1-6, with Elp3 conferring HAT activity. Elongator is conserved in yeast, plants and humans. In humans, mutations in Elp genes cause neuronal diseases. In plants, Elongator is a positive regulator of cell proliferation during leaf and root growth. Consequently, Arabidopsis Elongator mutants (elo) have narrow leaves and short roots; additionally, germination, vegetative growth and reproductive development are also affected. Mutants have altered auxin signaling, and a number of auxin-related genes are among those differentially expressed in the mutant. Only two genes have been confirmed as targeted by Elongator during RNAPII transcription elongation, including the light-regulated auxin response regulator IAA3/SHY2.
Project description:Environmental stimuli-triggered stomatal movement is a key physiological process that regulates CO<sub>2</sub> uptake and water loss in plants. Stomata are defined by pairs of guard cells that perceive and transduce external signals, leading to cellular volume changes and consequent stomatal aperture change. Within the visible light spectrum, red light induces stomatal opening in intact leaves. However, there has been debate regarding the extent to which red-light-induced stomatal opening arises from direct guard cell sensing of red light versus indirect responses as a result of red light influences on mesophyll photosynthesis. Here we identify conditions that result in red-light-stimulated stomatal opening in isolated epidermal peels and enlargement of protoplasts, firmly establishing a direct guard cell response to red light. We then employ metabolomics workflows utilizing gas chromatography mass spectrometry and liquid chromatography mass spectrometry for metabolite profiling and identification of Arabidopsis guard cell metabolic signatures in response to red light in the absence of the mesophyll. We quantified 223 metabolites in Arabidopsis guard cells, with 104 found to be red light responsive. These red-light-modulated metabolites participate in the tricarboxylic acid cycle, carbon balance, phytohormone biosynthesis and redox homeostasis. We next analyzed selected Arabidopsis mutants, and discovered that stomatal opening response to red light is correlated with a decrease in guard cell abscisic acid content and an increase in jasmonic acid content. The red-light-modulated guard cell metabolome reported here provides fundamental information concerning autonomous red light signaling pathways in guard cells.
Project description:To understand the transcript regulation of early Arabidopsis seedlings developments with different chemicals under continuous blue light irradiation.
Project description:The aim of this study was to perform a transcriptional characterization of the Arabidopsis eds4 mutant. To this end two separate experiments were performed: Experiment 1: comparison of the transcriptional profile (RNA-seq) of eds4 Arabidopsis mutants in contrast to wild type Col-0 accession grown under continuous light conditions. Experiment 2: Analysis of the distribution of transcripts (RNA-seq) between nucleus and cytoplasm in the eds4 Arabidopsis mutants in comparison to wild type Col-0 plants grown under continuous light conditions.
Project description:Sun-loving plants have the ability to detect and avoid shading through sensing of both blue and red light wavelengths. Higher plant cryptochromes (CRYs) control how plants modulate growth in response to changes in blue light. For growth under a canopy, where blue light is diminished, CRY1 and CRY2 perceive this change and respond by directly contacting two bHLH transcription factors, PIF4 and PIF5. These factors are also known to be controlled by phytochromes, the red/far-red photoreceptors; however, transcriptome analyses indicate that the gene regulatory programs induced by the different light wavelengths are distinct. Our results indicate that CRYs signal by modulating PIF activity genome-wide, and that these factors integrate binding of different plant photoreceptors to facilitate growth changes under different light conditions. We performed whole-genome transcriptome (mRNA-seq) analysis on 5-day-old Arabidopsis thaliana Columbia wild-type (WT) and pif4pif5 seedlings exposed to low blue-light (LBL) or mock-treated for 1, 6 and 24 hours. In addition we performed mRNA-seq on WT, 35S::PIF4-9xMyc-6x-His-3xFlag(Flash) and 35S::PIF5-9xMyc-6x-His-3xFlag (Flash) seedlings treated with LBL or mock-treated for 16 hours.
Project description:Light is a major determinant of plant growth and survival. NONEXPRESSER OF PATHOGENESIS-RELATED GENES 1 (NPR1) acts as a receptor for salicylic acid (SA) and serves as the key regulator of SA-mediated immune responses. However, the mechanisms by which plants integrate light and SA signals in response to environmental changes, as well as the role of NPR1 in regulating plant photomorphogenesis, remain poorly understood. This study shows that SA promotes plant photomorphogenesis by regulating PHYTOCHROME INTERACTING FACTOR 4 (PIF4). Specifically, NPR1 promotes photomorphogenesis under blue light by facilitating the degradation of PIF4 through light-induced polyubiquitination. NPR1 acts as a substrate adaptor for the CULLIN3-based E3 ligase, which ubiquitinates PIF4 at Lys129, Lys252, and Lys428, and leading to PIF4 degradation via the 26S proteasome pathway. Genetically, PIF4 is epistatic to NPR1 in the regulation of blue light-–induced photomorphogenesis, suggesting it acts downstream of NPR1. Furthermore, cryptochromes mediate the polyubiquitination of PIF4 by NPR1 in response to blue light by promoting the interaction and ubiquitination between NPR1 and PIF4. Transcriptome analysis revealed that, under blue light, NPR1 and PIF4 coordinately regulate numerous downstream genes related to light and auxin signaling pathways. Overall, these findings unveil a role for NPR1 in photomorphogenesis, highlighting a mechanism for post-translational regulation of PIF4 in response to blue light. This mechanism plays a pivotal role in the fine-tuning of plant development, enabling plants to adapt to complex environmental changes.
Project description:Purpose: Overexpression of VDE, ZEP and PsbS (VPZ) in plants confers enhanced dynamics of non-photochemical quenching of NPQ under FL light. VPZ overexpression in tobacco has been reported to increase plant biomass under fluctuating light. However, our work demonstrates that such strategy had no advantageous effect when asssayed in Arabidopsis thaliana. To investigate whether this observation is due to impairements in signaling pathways due to the expression of VPZ in Arabidopsis thaliana, transcriptome profiles of VPZ plants exposed to fluctuating light or high light were conducted. Methods: mRNA-Seq libraries were prepared from 21-d-old Col0 plants and VPZ lines #2 and #4 cultivated under standard control conditions and then exposed to fluctuating light or high light for 6h and 30 h. Standard Illumina protocols were used for mRNA-Seq sequencing. Triplicates for 3 independent plants were used. Adaptor sequences were removed with Trimmomatic and resulting reads mapped to the Arabidopsis genome (Araport11) with Tophat 2.1.1. Normalised counts reads were quantified with featureCounts to provide processed data files and differential expression analysis were conducted with the DEseq2 pipeline. Results: mRNA-Seq libraries contained app. 9 milion reads each. Transcript analysis for differential gene expression was conducted according to the Tophat/featureCounts/DESeq2 pipeline. To declare significant differences, a cut-off for absolute log2(FC) ≥ 1 compared to the initial timepoint (0h) and FDR ≤ 0.05 was applied. Significant transcripts exclusively found for Col0 and both VPZ lines in each time-point were considered for subsequent analysis. Accordingly, 528 and 415 transcripts (6h and 30h) were found for Col0, and 326 and 896 (6h and 30h) for the VPZ under control conditions. For FL, 490 and 591 transcripts qualified as specific (6h and 30h) for Col0 and 938 and 401 (6h and 30h) for VPZ. Strikingly, the amount of transcripts raised to 2847 and 2902 DEGs (6h and 30h) for Col0, whereas only 546 and 304 (6h and 30h) were detected for VPZ under HL. transcripts). Conclusions: the overexpression of VPZ in Arabidopsis leads to particular transcriptome response under fluctuating light related to changes in photosynthesis and response to abscisic acid, among all. However, Col0 displayed wider transcriptome responses than VPZ after exposure to high light .
Project description:In order to elucidate the role of the single Marchantia B-GATA ortholog in response to high light intensities, a transcriptomic analysis of Marchantia polymorpha BoGa, Mpb-gata1 mutants and MpB-GATA1ox under high-ligh stress conditions was performed.