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Global Identification of Potential Gene Biomarkers Associated with Ozone-induced Foliar Injury in Rice Seedling Leaves by Correlating their Symptom Severity with Transcriptome Profiling

ABSTRACT: A combined approach of evaluating ozone (O3)-caused foliar injury symptom and global gene expression profiling was used to identify potential genes associated with severity of injury on leaves of O3 (200 ppb)-fumigated (1, 12, 24, 48, and 72 h) two-week-old rice (cv. Nipponbare) seedling along with appropriate control. Foliar injuries were evaluated up to 72 h using both qualitative visual scale and quantitative RGB (red-green-blue) image analysis methods. The (R-G)/(R+G) was found as the optimal quantitative RGB parameter to assess the foliar injury. Large-scale transcript profiling of leaves identified 270 genes linked with foliar injury. Of these genes, the expression levels of 139 genes showed significant differences (P < 0.05) between leaves without and with injury symptoms. When a rigorous correlation test was applied on these genes for their expression changes and relative (R-G)/(R+G) parameters, the expression of 93 genes were found to increase with increased foliar severity up to 72 h, showing a positive, tight correlation between a subset of gene expression and commonly observed O3-triggerred symptom of foliar injury with correlation coefficient below -0.80. Of 93 genes, genes involved in metabolism (29%) formed a major functional category. Reconstruction of the metabolic networks with identified metabolic genes provided insight into the cellular responses such as photorespiration, biosynthesis of secondary metabolites, and detoxification. The O3 effect on these cellular responses has been previously reported based on physiological and biochemical studies, validating our approach used in this study to globally identify O3-responsive biomarkers tightly linked with foliar injury symptom. This study provides evidence for the presence of large number of genes associated with the foliar injury symptom than thought before, and could serve as a resource of potential biomarkers to study mechanisms of visible injury development by O3.

ORGANISM(S): Oryza sativa Oryza sativa Japonica Group

PROVIDER: GSE34256 | GEO | 2011/12/10

SECONDARY ACCESSION(S): PRJNA149757

REPOSITORIES: GEO

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Project description:A combined approach of evaluating ozone (O3)-caused foliar injury symptom and global gene expression profiling was used to identify potential genes associated with severity of injury on leaves of O3 (200 ppb)-fumigated (1, 12, 24, 48, and 72 h) two-week-old rice (cv. Nipponbare) seedling along with appropriate control. Foliar injuries were evaluated up to 72 h using both qualitative visual scale and quantitative RGB (red-green-blue) image analysis methods. The (R-G)/(R+G) was found as the optimal quantitative RGB parameter to assess the foliar injury. Large-scale transcript profiling of leaves identified 270 genes linked with foliar injury. Of these genes, the expression levels of 139 genes showed significant differences (P < 0.05) between leaves without and with injury symptoms. When a rigorous correlation test was applied on these genes for their expression changes and relative (R-G)/(R+G) parameters, the expression of 93 genes were found to increase with increased foliar severity up to 72 h, showing a positive, tight correlation between a subset of gene expression and commonly observed O3-triggerred symptom of foliar injury with correlation coefficient below -0.80. Of 93 genes, genes involved in metabolism (29%) formed a major functional category. Reconstruction of the metabolic networks with identified metabolic genes provided insight into the cellular responses such as photorespiration, biosynthesis of secondary metabolites, and detoxification. The O3 effect on these cellular responses has been previously reported based on physiological and biochemical studies, validating our approach used in this study to globally identify O3-responsive biomarkers tightly linked with foliar injury symptom. This study provides evidence for the presence of large number of genes associated with the foliar injury symptom than thought before, and could serve as a resource of potential biomarkers to study mechanisms of visible injury development by O3. Comparison between healthy rice seedling leaves and ozone treated (for 48 h and 72 h) rice seedling leaves was performed. Three biological replicates (5 leaves in each replicate; pooled) were used, and dye-swaped.

Project description:Background: Ozone (O3) is the predominant oxidant air pollutant associated with respiratory inflammation, lung dysfunction, and worsening preexisting airway diseases. We determined that TNFR signlaing pathway plays a key role in lung injury and inflammation caused by O3 in mice. However, downstream molecular mechanisms underlying TNFR pathway have not been investigated. Methods: To investigate the role of TNFR pathway in gene expression changes, Tnfr1/2-deficient (Tnfr-/-) and wild-type (Tnfr+/+, C57BL/6J) mice were exposed to air or 0.3-ppm O3. Total RNAs were isolated from lung homogenates and cDNA microarray analyses were performed to elucidate TNFR-directed transcriptomics in basal lungs (air-exposed) as well as in the lung exposed to time course of O3 (24, 48, and 72 hr). Results: O3 caused time-dependent changes in lung gene expressions with the greatest transcriptome changes at 48-72 hr of exposure in Tnfr+/+ mice. At early time of exposure (24 hr), acute phase and inflammatory responses gene as well as redox and lipid metabolism genes were increased by O3 while cell cycle and DNA damage repair genes were markedly increased by O3 at later time points (48-72 hr). Compared to Tnfr+/+ mice, Tnfr-/- mice had lowered expression of inflammatory response and vascular disorder-related genes at baseline (air). After O3 exposure, Tnfr-/- had enhanced expression of immune and inflammatory genes at 24 hr, indicating compensatory or adpative poentiation of immunity in Tnfr-/- mice. At 48 hr of O3 exposure, Tnfr-/- mice showed suppressed expression of genes involved in epithelial proliferation, inflammatory cell influxes and epithelial injury, compared to Tnfr+/+ mice. At 72 hr of O3 exposure, neurodegeneration and neurotransmitter transport genes were suppressed in Tnfr-/- than in Tnfr+/+. Conclusion: Overall, deficiency of TNFR-mediated signaling in mouse lungs altered transcriptomes to protect lungs from O3-induced inflammation, cell proliferation, oxidative stress, and neuronal disorders.

Project description:Background: The mechanisms underlying ozone (O3)-induced pulmonary inflammation remain unclear. Interleukin (IL)-10 is an anti-inflammatory cytokine that is known to inhibit inflammatory mediators. Objectives: The current study investigated the molecular mechanisms underlying IL-10-mediated attenuation of O3-induced pulmonary inflammation in mice. Methods: Il10-deficient (Il10-/-) and wild type (Il10+/+) mice were exposed to 0.3-ppm O3 or filtered air for 24, 48 or 72 hr. Immediately following exposure, differential cell counts, and total protein (a marker of lung permeability) were assessed from bronchoalveolar lavage fluid (BALF). mRNA and protein levels of cellular mediators were determined from lung homogenates. We also utilized global mRNA expression analyses of lung tissue with Ingenuity Pathway Analyses (IPA) to identify patterns of gene expression through which IL-10 modifies O3-induced inflammation. Results: Mean numbers of BALF polymorphonuclear leukocytes (PMNs) were significantly greater in Il10-/- mice than in Il10+/+ mice after exposure to O3 at all time points tested. O3-enhanced nuclear NF-kB translocation was elevated in the lungs of Il10-/- compared to Il10+/+ mice. Gene expression analyses revealed several key IL-10 and O3-dependent mediators, including IL-6, MIP-2, IL-1 and CD86. Conclusions: Results indicated that IL-10 protects against O3-induced pulmonary neutrophilic inflammation and cell proliferation. Moreover, gene expression analyses identified three response pathways and several novel genetic targets (e.g. Ccr1, Socs3, Il33, Hat1, and Gale) through which IL10 may modulate the innate and adaptive immune response. These novel mechanisms of protection against the pathogenesis of O3-induced pulmonary inflammation may also provide potential therapeutic targets to protect susceptible individuals. PARALLEL study design with 26 samples. Biological replicates: 2 to 3 replicates per group with wild type air exposed animals as controls for each time point (24, 48, 72 hours). Time-Course, Dose-Response, Strain comparison

Project description:Here we performed a transcriptomic study on complete symptom development process of CMV-infected Nicotiana tabacum using Solexa/Illumina's high-throughput digital gene expression (DGE) system. 12 DGE libraries (from six virus-infected samples and six corresponding mock-inoculated samples) were constructed, and the gene expression variations between the virus-infected sample and the mock-inoculated sample in each symptom stage were compared. Thousands of differentially expressed genes were obtained by the comparison, and KEGG pathway analysis of these genes suggested that many biological processes (such as phtosynthesis, pigment metabolism and plant-pathogen interaction) were related to the symptom development. The authenticity of the DGE data was further confirmed by analyzing real-time RT-PCR using several random-selected genes. We sequenced a cDNA library constructed from mixture of total RNA from six virus-infected samples and six mock-inoculated samples to get gene information for tobacco leaves in different symptom stages, including vein clearing, mosaic, severe chlorosis, partial recovery, total recovery and re-mosaic, and 95,916 Unigenes were obtained Tobacco leaves were inoculated by CMV-infected leaf homogenate and healthy leaf homogenate, respectivley. Six time points with different symptom stage were selected, and one virus-infect sample and one mock-inoculated sample were collected at each time. In order to average out variation of different plants, five leaves from five different plants were mixed to prepare every RNA sample. Twelve individual tag libraries of samples (six infected samples and six mock-inoculated samples) were constructed in parallel. For the gene expression analysis, the twelve samples were grouped into six groups, and each group contained a virus-infected sample and a mock-inoculated sample collected at the same time. In each group, the DGE data of virus-infected sample were compared to that of mock-inoculated sample to obtain the gene expression variations. Illumina sequencing of transcripts from virus-infected and mock-inoculated samples to get gene information for tobacco leaves in different symptom stages. In order to get more gene information, the systemically infected leaves and mock-inoculated leaves were harvested at six time points and five leaves from five different plants were collected at each time point. The RNA-Seq analysis provided gene information for mock-inoculated and virus-infected tobacco leaves in different symptom stages.

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Global Identification of Potential Gene Biomarkers Associated with Ozone-induced Foliar Injury in Rice Seedling Leaves by Correlating their Symptom Severity with Transcriptome Profiling

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