The ultraviolet-B (UV-B) portion of the solar radiation functions as an environmental signal for which plants have evolved specific and sensitive UV-B perception systems. The UV-B-specific UV RESPONSE LOCUS 8 (UVR8) and the multifunctional E3 ubiquitin ligase CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1) are key regulators of the UV-B response. We show here that uvr8-null mutants are deficient in UV-B-induced photomorphogenesis and hypersensitive to UV-B stress, whereas overexpression of UVR8 results ...[more]
Project description:Sporophytes of Saccharina latissima were exposed for two weeks to 12 different combinations of photosynthetically active radiation and UVR at three different temperatures (2,7,12 C). Maximum quantum yield of photosystem II was determined twice a week during the experimental duration for observing the extent of photoinhibition. For investigating molecular mechanisms of acclimation to high photosynthetically radiation, and UVR gene expression profiles were assessed through microarray hybridizations.
Project description:To explore possible interactive effects of UV-radiation, temperature and growth conditions, cultivated and field sporophytes of Saccharina latissima were exposed for 24h to UV-radiation at three different temperatures (2,7 & 12°C). Gene expression profiles under UV-radiation at different temperatures were assessed through microarray hybridizations, afterwards comparisons of gene expression profiles in field and culture sporophytes were carried out.
Project description:Ultra-violet (UV) and high-intensity visible (VIS) radiation are environmental stressors known to harm photosynthetic organisms through the generation of reactive intermediates that damage photosynthetic machinery. This study shows the potential of using a thermoacidophilic red alga of the order Cyanidiales to model in situ algal gene expression dynamics as a function of UV exposure and seasonal shifts in UV-VIS intensity. These algae exhibit a dynamic seasonal biomass fluctuation referred to as 'mat decline' where viability drastically decreases as seasonal UV-VIS irradiance intensity increases. In Yellowstone National Park (YNP), temporal experiments coupling UV irradiance manipulations (filtering) with whole-community transcription profiling revealed significant cyanidial gene expression changes occurring as a result of exposure to UV, and that patterns of response adjust across low and high irradiance time periods. Separate analyses examined genes responding to either increasing seasonal UV or VIS intensity, or by the combined effects of both irradiance wavelengths (UV and VIS). Results not only corroborated known physiological changes to solar irradiance, but also suggested the strategies employed to deal with excess VIS and UV intensity may be highly integrated. Finally, a suite of comparative analyses determined the relative utility of environmental transcriptomics technologies in studying ecologically-relevant expression patterns. Results suggest in situ expression profiles will improve understanding of how photosynthetic organisms are responding to environmental stressors as they are observed in nature. 16 samples with 3 biological replicates each.
Project description:In the present study we have used a new custom made Affymetrix GrapeGen GeneChip to investigate gene expression responses of grapevine cultivar Malbec to one dose of biologically effective UV-B radiation (4.75 kJ m-2 d-1), administered at two different intensities (16 h, to 8.25 µW cm-2 or 4 h, to 33 µW cm2 UV-B).
Project description:Photosynthesis is arguably the most important biological process on earth. In plants, energy harvested in photosynthesis is converted into sugar and starch, which are important products from species with agronomic interest. During the photosynthesis in the chloroplast, the intermediate carbon metabolites (triose phosphates) produced by the Calvin cycle can either be exported to the cytosol for sucrose synthesis or stay in the chloroplast for starch synthesis (formation). Two fructose-1,6-bisphosphatase (FBPase) enzymes, the chloroplastidial (cpFBPaseI) and the cytosolic (cyFBPase) isoforms, catalyse the first irreversible step during the conversion of triose phosphate to starch or sucrose, respectively. Recently, another cpFBPase isoform (cpFBPaseII) with unknown function was identified. It has been reported that the reduction of cyFBPase or cpFBPaseI activity leads to an alteration in starch and sucrose content. In our laboratory, Arabidopsis thaliana knock-out mutants for the cyFBPase and cpFBPaseI are now available. The objective this research project is to identify and functionally characterize genes differentially expressed in Arabidopsis thaliana knock-out mutants lacking FBPase genes. We make use of high throughput methodologies, such as the transcriptomic and proteomic analyses which represent invaluable tools to identify new loci responsible for agronomically important traits. Three independent biological replicates were used for each type of sample. Three hybridizations were performed, representing the three independent biological replicates, being one of them a dye swap
Project description:In dense plant stands, the ratio between red and far-red (R:FR) light declines and shade intolerant species will respond to this cue for future shade by inducing the shade avoidance syndrome (SAS), enabling them to outgrow their neighbours. Shade tolerant species from the forest understory are unable to outgrow neighbouring trees and will suppress SAS. Although the molecular mechanisms underlying SAS are well studied in various species, mechanisms of SAS-suppression in shade tolerant species have rarely been studied. We applied RNA sequencing on Geranium pyrenaicum and G. robertianum, two wild species with contrasting growth responses to low R:FR light. G. pyrenaicum strongly induces petiole elongation when exposed to low R:FR light, at any time of the photoperiod. Contrastingly, G. robertianum only induces this response early in the day, and suppresses petiole growth in low R:FR light at the end of the photoperiod, which results after 24 hours in a net difference with control treatments of zero. We compared expression patterns in the most apical (most responsive) part of the second petioles, in two-week-old Geranium plants (two leaf stage) after 2 and 11.5 hours of far-red light enrichment. This way, we identified a number of novel candidate regulators of shade avoidance, and differential phytochrome control of plant immunity genes in the two species. For de-novo assembly of the reference transcriptomes, we pooled petiole- and leaf lamina tissue exposed to normal white light (180 mol m-2 s-1 PAR, R:FR 1.8, ± 60 mol m-2 s-1 blue light), low R:FR light (0.2), blue-depleted light (± 4 mol m-2 s-1 blue) and green shade (50 mol m-2 s-1 PAR, R:FR 0.45, ± 13 mol m-2 s-1 blue) for 2, 11.5 and 24 hours. Libraries of these samples were normalized, Illumina sequenced, and together with sequences of non-normalized petiole samples of the expression analysis constructed into a reference transcriptome for each species, using the Trinity protocol. Transcripts were clustered into orthologue clusters using the ortho-MCL clustering technique. Non-normalized libraries of samples (control vs. low R:FR light, 2 and 11.5 hours after start of the treatment) were sequenced and aligned to the newly assembled transcriptomes. Read counts were summed per orthologue cluster before statistical analysis was proceeded.
Project description:Detect the global transcriptional changes occuring during spreading and maintenance of systemic post transcriptional silencing . Test the hypothesis that activation of systemic PTGS induces parallel antiviral defense pathways. Gene expression was analysed by MACE method (Massive Analysis of cDNA Ends) on total RNA extracted from leaf tissues of WT plants (WT), and GFP6.4 presenting no-silencing (NS sample), ongoing spreading of silencing (OS) and maintenance of silencing (SS). Plants were grown in parallel, and silencing state was monitored under UV. After 3 weeks of growth, total RNAs were extracted using the Trizol method from leaf tissues of 2-3 leaf stage plants. A total of 4 plants were sampled per variable (WT/NS/OS/SS). RNA from 4 plants were pooled and sequenced.
Project description:Plant cellular damage promotes the interaction of lipoxygenases (LOX) with free fatty acids to yield 9- and 13-hydroperoxides which are further metabolized into diverse oxylipins. The enzymatic action of 13-LOX on linolenic acid enables production of 12-oxo-phytodienoic acid (12-OPDA) and its downstream products, jointly known as jasmonates. As signals, jasmonates have related yet distinct roles in the regulation of plant resistance against insect and pathogen attack. An additional and conceptually parallel pathway involving 9-LOX activity on linoleic acid leads to the production of 10-oxo-11-phytoenoic acid (10-OPEA). Despite structural similarity to jasmonates, physiological roles for 10-OPEA have remained unclear. Both 12-OPDA and 10-OPEA equally promote the transcription of numerous defense genes encoding glutathione S-transferases, cytochrome P450s, and pathogenesis-related proteins; however, 10-OPEA activity diverges in the context of reduced protease inhibitor transcript accumulation. To identify additional differential responses, we subsequently performed whole transcriptome analyses using RNAseq. These comparisons provide a platform for further examination of plant response specificity to the cyclopentenone 10-OPEA. A total of 12 samples were analyzed, comprised of two treatments (10-OPEA and 12-OPDA) and a DMSO carrier control (5%DMSO/0.1%Tween 20 in H20), all in replicates of four.