Project description:Transcriptional profiling of arsenic-induced toxicity and tolerance in Arabidopsis plants of different ecotypes Arsenic (As) is a toxic metalloid found ubiquitously in the environment and has widely been known as an acute poison and carcinogen. As toxicity is a major factor leading to root growth inhibition in plants. However, the molecular mechanisms of plants in response to As has not been extensively characterized. In this study, Arabidopsis ecotypes that are As-tolerant (Col-0) and -sensitive (Ws-2) were used to conduct a transcriptome analysis of the response to As (V). To begin elucidating the molecular basis of As toxicity and tolerance in Arabidopsis, seedlings of Col-0 and Ws-2 were subjected to As treatment. The root elongation rate of Col-0 was significantly higher than that of Ws-2 when exposed to As. The tolerant ecotype (Col-0) demonstrated lower accumulation of As when compared to the responses observed in the sensitive Ws-2. Subsequently, the effect of As exposure on genome-wide gene expression was examined in the two ecotypes. Comparative analysis of microarray data identified groups of genes with common and specific responses to As between Col-0 and Ws-2. The genes related to heat responses and oxidative stresses belonged to common responses, indicating conserved stress-associated changes across two ecotypes. The majority of specific responsive genes were those encoding heat shock proteins, heat shock factors, ubiquitin and transporters. The data suggested that metal transport and maintenance of protein structure may be important mechanisms for toxicity and tolerance to As. This study presents comprehensive surveys of global transcriptional regulation and identifies stress- and tolerance-associated genes in response to As. Comparison of Arabidopsis ecotype Col-0 and Ws-2 in response to As with the Affymetrix GeneChip were performed by the Affymetrix Gene Expression Service Lab (http://ipmb.sinica.edu.tw/affy/), supported by Academia Sinica, Taiwan
Project description:Transcriptional profiling of arsenic-induced toxicity and tolerance in Arabidopsis plants of different ecotypes Arsenic (As) is a toxic metalloid found ubiquitously in the environment and has widely been known as an acute poison and carcinogen. As toxicity is a major factor leading to root growth inhibition in plants. However, the molecular mechanisms of plants in response to As has not been extensively characterized. In this study, Arabidopsis ecotypes that are As-tolerant (Col-0) and -sensitive (Ws-2) were used to conduct a transcriptome analysis of the response to As (V). To begin elucidating the molecular basis of As toxicity and tolerance in Arabidopsis, seedlings of Col-0 and Ws-2 were subjected to As treatment. The root elongation rate of Col-0 was significantly higher than that of Ws-2 when exposed to As. The tolerant ecotype (Col-0) demonstrated lower accumulation of As when compared to the responses observed in the sensitive Ws-2. Subsequently, the effect of As exposure on genome-wide gene expression was examined in the two ecotypes. Comparative analysis of microarray data identified groups of genes with common and specific responses to As between Col-0 and Ws-2. The genes related to heat responses and oxidative stresses belonged to common responses, indicating conserved stress-associated changes across two ecotypes. The majority of specific responsive genes were those encoding heat shock proteins, heat shock factors, ubiquitin and transporters. The data suggested that metal transport and maintenance of protein structure may be important mechanisms for toxicity and tolerance to As. This study presents comprehensive surveys of global transcriptional regulation and identifies stress- and tolerance-associated genes in response to As.
Project description:Drought is a major abiotic stress that threatens global food security. Circular RNAs (circRNAs) are endogenous RNAs. How these molecules influence plant stress responses remains elusive. Here, a large scale circRNA profiling identified 2174 and 1354 high-confidence circRNAs in maize and Arabidopsis, respectively, and most were differentially expressed in response to drought. A substantial number of drought-associated circRNA hosting genes were involved in conserved or species-specific pathways in drought responses. Comparative analysis revealed that circRNA biogenesis was more complex in maize than in Arabidopsis. In most cases, maize circRNAs were negatively correlated with sRNA accumulation. In 368 maize inbred lines, the circRNA-hosting genes were enriched for SNPs associated with circRNA expression and drought tolerance, implying either important roles of circRNAs in maize drought responses or their potential use as biomarkers for breeding drought-tolerant maize. Additionally, the expression levels of circRNAs derived from drought-responsible genes encoding calcium-dependent protein kinase and cytokinin oxidase/dehydrogenase were significantly associated with drought tolerance of maize seedlings. Specifically, Arabidopsis plants overexpressing circGORK (Guard cell outward-rectifying K+-channel) were hypersensitive to ABA, but insensitive to drought, suggesting a positive role of circGORK in drought tolerance. We report the transcriptomic profiling and transgenic studies of circRNAs in plant drought responses, and provide evidences highlighting the universal molecular mechanisms involved in plant drought tolerance.
Project description:Aluminum (Al) toxicity, which is caused by the solubilization of Al3 in acid soils resulting in inhibition of root growth and nutrient/water acquisition, is a serious limitation to crop production, because up to one-half of the world?s potentially arable land is acidic. To date, however, no Al tolerance genes have yet been cloned. The physiological mechanisms of tolerance are somewhat better understood; the major documented mechanism involves the Al-activated release of Al-binding organic acids from the root tip, preventing uptake into the primary site of toxicity. In this study, a quantitative trait loci analysis of Al tolerance in Arabidopsis was conducted, which also correlated Al tolerance quantitative trait locus (QTL) with physiological mechanisms of tolerance. The analysis identified two major loci, which explain approximately 40% of the variance in Al tolerance observed among recombinant inbred lines derived from Landsberg erecta (sensitive) and Columbia (tolerant). We characterized the mechanism by which tolerance is achieved, and we found that the two QTL cosegregate with an Al-activated release of malate from Arabidopsis roots. Although only two of the QTL have been identified, malate release explains nearly all (95%) of the variation in Al tolerance in this population. Al tolerance in Landsberg erecta Columbia is more complex genetically than physiologically, in that a number of genes underlie a single physiological mechanism involving root malate release. These findings have set the stage for the subsequent cloning of the genes responsible for the Al tolerance QTL, and a genomics-based cloning strategy and initial progress on this are also discussed.
Project description:Aluminum (Al) toxicity, which is caused by the solubilization of Al3 in acid soils resulting in inhibition of root growth and nutrient/water acquisition, is a serious limitation to crop production, because up to one-half of the world?s potentially arable land is acidic. To date, however, no Al tolerance genes have yet been cloned. The physiological mechanisms of tolerance are somewhat better understood; the major documented mechanism involves the Al-activated release of Al-binding organic acids from the root tip, preventing uptake into the primary site of toxicity. In this study, a quantitative trait loci analysis of Al tolerance in Arabidopsis was conducted, which also correlated Al tolerance quantitative trait locus (QTL) with physiological mechanisms of tolerance. The analysis identified two major loci, which explain approximately 40% of the variance in Al tolerance observed among recombinant inbred lines derived from Landsberg erecta (sensitive) and Columbia (tolerant). We characterized the mechanism by which tolerance is achieved, and we found that the two QTL cosegregate with an Al-activated release of malate from Arabidopsis roots. Although only two of the QTL have been identified, malate release explains nearly all (95%) of the variation in Al tolerance in this population. Al tolerance in Landsberg erecta Columbia is more complex genetically than physiologically, in that a number of genes underlie a single physiological mechanism involving root malate release. These findings have set the stage for the subsequent cloning of the genes responsible for the Al tolerance QTL, and a genomics-based cloning strategy and initial progress on this are also discussed. A replicate experimental design type is where a series of replicates are performed to evaluate reproducibility or as a pilot study to determine the appropriate number of replicates for a subsequent experiments. Computed
Project description:In spite of many reports on the toxicity of silver nanoparticles (AgNPs), the mechanisms underlying the toxicity are far from clear. The present study conducted transcriptome and microRNAome sequencing for Euplotes vannus to understand the molecular mechanisms by which this protist copes with AgNPs exposure. By transcriptome profiling, 1884 and 5834 differentially expressed genes (DEGs) were identified after one hour and 12 hours exposure to 15 mg/L AgNPs, respectively. From microRNAsome profiling, totally 16 differentially expressed microRNAs were identified under AgNPs stress.In spite of many reports on the toxicity of silver nanoparticles (AgNPs), the mechanisms underlying the toxicity are far from clear. The present study conducted transcriptome and microRNAome sequencing for Euplotes vannus to understand the molecular mechanisms by which this protist copes with AgNPs exposure. By transcriptome profiling, 1884 and 5834 differentially expressed genes (DEGs) were identified after one hour and 12 hours exposure to 15 mg/L AgNPs, respectively. The DEGs were significantly enriched in macropinocytosis and phagocytic vesicles suggesting that the uptake of AgNPs may be mediated by endocytic pathways, while the differential expression of ABC transporters and copper-transporting ATPase implicates active efflux transport of Ag. Several DNA repair pathways were also significantly enriched with differentially expressed cell cycle control genes implying that exposure to AgNPs might have caused DNA damage and G2/M cell cycle arrest. The damage might have resulted from increased ROS production, as evidenced by elevated expression of several antioxidants genes to combat oxidative stress. From microRNAsome profiling, totally 16 differentially expressed microRNAs were identified under AgNPs stress. Integrated analysis of the microRNA and mRNA expression profiles found that the differentially expressed microRNAs target a series of genes involved in many important biological processes, suggesting that E. vannus exposure elicited a broad post-transcriptional regulatory mechanism through microRNAs–mRNAs–biological functions network to cope with the toxicity of AgNPs.
Project description:In spite of many reports on the toxicity of silver nanoparticles (AgNPs), the mechanisms underlying the toxicity are far from clear. The present study conducted transcriptome and microRNAome sequencing for Euplotes vannus to understand the molecular mechanisms by which this protist copes with AgNPs exposure. By transcriptome profiling, 1884 and 5834 differentially expressed genes (DEGs) were identified after one hour and 12 hours exposure to 15 mg/L AgNPs, respectively. From microRNAsome profiling, totally 16 differentially expressed microRNAs were identified under AgNPs stress.In spite of many reports on the toxicity of silver nanoparticles (AgNPs), the mechanisms underlying the toxicity are far from clear. The present study conducted transcriptome and microRNAome sequencing for Euplotes vannus to understand the molecular mechanisms by which this protist copes with AgNPs exposure. By transcriptome profiling, 1884 and 5834 differentially expressed genes (DEGs) were identified after one hour and 12 hours exposure to 15 mg/L AgNPs, respectively. The DEGs were significantly enriched in macropinocytosis and phagocytic vesicles suggesting that the uptake of AgNPs may be mediated by endocytic pathways, while the differential expression of ABC transporters and copper-transporting ATPase implicates active efflux transport of Ag. Several DNA repair pathways were also significantly enriched with differentially expressed cell cycle control genes implying that exposure to AgNPs might have caused DNA damage and G2/M cell cycle arrest. The damage might have resulted from increased ROS production, as evidenced by elevated expression of several antioxidants genes to combat oxidative stress. From microRNAsome profiling, totally 16 differentially expressed microRNAs were identified under AgNPs stress. Integrated analysis of the microRNA and mRNA expression profiles found that the differentially expressed microRNAs target a series of genes involved in many important biological processes, suggesting that E. vannus exposure elicited a broad post-transcriptional regulatory mechanism through microRNAs–mRNAs–biological functions network to cope with the toxicity of AgNPs.
Project description:Gene expression profiling in soybean under aluminum stress: mechanisms of magnesium amelioration of aluminum toxicity at gene expression level. Micro-molar concentrations of magnesium in culture solution has been shown to ameliorate Al toxicity in soybean and other leguminous species. Different theories have been proposed to explain the chemical mechanisms of how the two ions interact to neutralize the toxic effect of aluminum in the plant root system. To understand the molecular mechanisms of the phenomenon at the gene expression level in soybean, we undertook a comparative transcriptome analysis in Al-tolerant and Al-sensitive genotypes treated with aluminum alone or aluminum plus magnesium using DNA microarrays. The results revealed magnesium enhances Al-tolerance level in the Al-tolerant genotype by down-regulating genes commonly induced in response to Al toxicity. We hypothesized that the magnesium-mediated alleviation of Al toxicity in the Al-tolerant genotype emanates from reduction in energy expenditure of gene expression induced in response to Al stress. Conversely, magnesium appears to ameliorate Al toxicity in the sensitive genotype by dual mechanisms of increasing the expression level of several genes involved in Al-tolerance and decreasing the expression level of most genes. Keywords: Soybean, aluminum toxicity, magnesium, transcriptome Two genotypes: PI 416937 (p) and Young (y); two treatments: Aluminum (Al) or Al+magnesium (Mg); two time points: 12 and 72 hrs; 3 replicates.