Ontology highlight
ABSTRACT:
PROVIDER: PRJNA1138505 | ENA |
REPOSITORIES: ENA
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Project description:Source-to-sink carbon (C) allocation driven by the sink strength, i.e., the ability of a sink organ to import C, plays a central role in tissue growth and biomass productivity. However, molecular drivers of sink strength have not been thoroughly characterized in trees. Auxin, as a major plant phytohormone, regulates the mobilization of photoassimilates in source tissues and elevates the translocation of carbohydrates toward sink organs, including roots. In this study, we used an ‘auxin-stimulated carbon sink’ approach to understand the molecular processes involved in the long-distance source-sink C allocation in poplar. Poplar cuttings were foliar sprayed with polar auxin transport modulators, including auxin enhancers (AE) (i.e., IBA and IAA) and auxin inhibitor (AI) (i.e., NPA), followed by a comprehensive analysis of leaf, stem, and root tissues using biomass evaluation, phenotyping, C isotope labeling, metabolomics, and transcriptomics approaches. Auxin modulators altered root dry weight and branching pattern, and AE increased photosynthetically fixed C allocation from leaf to root tissues. The transcriptome analysis identified highly expressed genes in root tissue under AE condition including transcripts encoding polygalacturonase and β-amylase that could increase the sink size and activity. Metabolic analyses showed a shift in overall metabolism including an altered relative abundance levels of galactinol, and an opposite trend in citrate levels in root tissue under AE and AI conditions. In conclusion, we postulate a model suggesting that the source-sink C relationships in poplar could be fueled by mobile sugar alcohols, starch metabolism-derived sugars, and TCA-cycle intermediates as key molecular drivers of sink strength.
2023-05-15 | GSE232245 | GEO
Project description:Plant respiration responses to elevated growth [CO2] are key uncertainties in predicting future crop and ecosystem function. In particular, the effects of elevated growth [CO2] on respiration over leaf development are poorly understood. This study tested the prediction that, due to greater whole-plant photoassimilate availability and growth, elevated [CO2] induces transcriptional reprogramming and a stimulation of nighttime respiration in leaf primordia, expanding leaves, and mature leaves of Arabidopsis thaliana. In primordia, elevated [CO2] altered transcript abundance, but not for genes encoding respiratory proteins. In expanding leaves, elevated [CO2] induced greater glucose content and transcript abundance for some respiratory genes, but did not alter respiratory CO2 efflux. In mature leaves, elevated [CO2] led to greater glucose, sucrose and starch content, plus greater transcript abundance for many components of the respiratory pathway, and greater respiratory CO2 efflux. Therefore, growth at elevated [CO2] stimulated dark respiration only after leaves transitioned from carbon sinks into carbon sources. This coincided with greater photoassimilate production by mature leaves under elevated [CO2] and peak respiratory transcriptional responses. It remains to be determined if biochemical and transcriptional responses to elevated [CO2] in primordial and expanding leaves are essential prerequisites for subsequent alterations of respiratory metabolism in mature leaves. Arabidopsis plants were grown in either ambient (370 ppm) or elevated (750 ppm) CO2. Leaf number 10 was harvested when it was a primordia, expanding, or mature in each of the CO2 treatments.
2014-04-04 | E-GEOD-56480 | biostudies-arrayexpress
Project description:Innate cellular defense mechanisms and viral countermeasures govern the outcome of pathogen exposure but the complex virus-host interplay remains poorly understood. Here, we developed a virus-guided technology platform where the pathogen itself reveals its cellular opponents. To accomplish this, we engineered replication-competent HIV-1 expressing single guide RNAs (sgRNAs) targeting potential antiviral genes in Cas9 expressing CD4+ T cells. Screening of HIV-1 constructs targeting >500 potential antiviral genes revealed that sgRNAs against GRN, CIITA, EHMT2, CEACAM3, CC2D1B, RHOA and HMOX1 provide significant advantages for viral replication. We verified that GRN and CIITA inhibit HIV-1 in primary CD4+ T cells by reducing viral transcription. Lack of the accessory nef gene increased selection for sgRNAs targeting SERINC5 and IFI16. Functional analyses demonstrated that Nef counteracts the inhibitory effects of IFI16. Altogether, we established a highly versatile, effective and robust approach that forces HIV-1 to reveal its cellular opponents.
2024-04-15 | GSE245526 | GEO
Project description:Responses to altered source–sink balance have been characterized in many crops at the physiological level, but the underlying genetic and molecular mechanisms are largely unknown. Detailed transcriptional profiling was performed in partially defoliated and shaded tomato plants to explore the effect of reduced source-to-sink ratio on molecular changes in the remaining source leaves. Transcription profiles of the remaining leaves 48 h after partial defoliation or partial shading were compared to leaves of control plants. Common significantly altered genes in the two treatments were assumed to be related to the reduced source-to-sink ratio. Sets of major genes in the abscisic acid, ethylene and gibberellin signal-transduction pathways were downregulated by both treatments. On the other hand, genes encoding cytokinin biosynthesis were upregulated. Most genes coding for transcription factors were also downregulated, especially those related to biotic and abiotic stress responses. Perhaps the most pronounced effect of reduced source-to-sink ratio was related to genes involved in the regulation of photosynthetic activity. Numerous genes coding for light-harvesting proteins, as well as those encoding plastocyanin, ferredoxin and ferredoxin NADP+ oxidoreductase were upregulated. Direct spectrophotometric analyses showed higher maximal potential activity of photosystem I with reduced source-to-sink ratio. As expected, the increased capacity for photosynthetic activity was associated with upregulation of almost all genes coding for the Calvin–Benson cycle and those encoding ATP biosynthesis in the mitochondria. Numerous transcriptional changes were observed 48 h after reducing source-to-sink ratio. Major genes in the photosynthetic-activity pathways were upregulated, whereas those in the pathways of defense mechanisms and responses to stress were downregulated. Genes involved in leaf senescence were also downregulated, suggesting that in addition to increased photosynthetic activity, the remaining leaves undergo a process of rejuvenation.
2023-08-01 | GSE201432 | GEO
Project description:In contrast to SIVagm, which does not cause disease in its natural simian host, HIV-1 expresses the accessory protein Vpu and encodes a Nef protein that fails to suppress T cell activation via down-modulation of CD3. Although both, Vpu and Nef have been implicated as pathogenicity determinants, their relevance for viral replication and disease progression in vivo has remained unclear. Here, we analyzed gene expression in African green monkeys infected with SIVagm chimeras differing in their expression of nef and/or vpu. We used microarrays to analyze global gene expression of African green monkeys in response to infection with SIVagm and found that the viral accessory nef and vpu genes co-determine the induction of distinct gene sets.
2018-03-02 | GSE103072 | GEO