Project description:Background: The soil environment is responsible for sustaining most terrestrial plant life on earth, yet we know surprisingly little about the important functions carried out by diverse microbial communities in soil. Soil microbes that inhabit the channels of decaying root systems, the detritusphere, are likely to be essential for plant growth and health, as these channels are the preferred locations of new root growth. Understanding the microbial metagenome of the detritusphere and how it responds to agricultural management such as crop rotations and soil tillage will be vital for improving global food production. Methods: The rhizosphere soils of wheat and chickpea growing under + and - decaying root were collected for metagenomics sequencing. A gene catalogue was established by de novo assembling metagenomic sequencing. Genes abundance was compared between bulk soil and rhizosphere soils under different treatments. Conclusions: The study describes the diversity and functional capacity of a high-quality soil microbial metagenome. The results demonstrate the contribution of the microbiome from decaying root in determining the metagenome of developing root systems, which is fundamental to plant growth, since roots preferentially inhabit previous root channels. Modifications in root microbial function through soil management, can ultimately govern plant health, productivity and food security.
Project description:Polycyclic aromatic hydrocarbons are common pollutants in soil, have negative effects on soil ecosystems, and are potentially carcinogenic. The Springtail (Collembola) Folsomia candida is often used as an indicator species for soil toxicity. Here we report a toxicogenomic study that translates the ecological effects of the polycyclic aromatic hydrocarbon phenanthrene in soil to the early transcriptomic responses in Folsomia candida. Microarrays were used to examine two different exposure concentrations of phenanthrene, namely the EC10 (24.95 mg kg-1 soil) and EC50 (45.80 mg kg-1 soil) on reproduction of this springtail, which evoked 405 and 251 differentially expressed transcripts, respectively. Fifty transcripts were differential in response to either concentration. Many transcripts encoding xenobiotic detoxification and biotransformation enzymes (phases I, II, and III) were upregulated in response to either concentration. Furthermore, indications of general and oxidative stress were found in response to phenanthrene. Chitin metabolism appeared to be disrupted particularly at the low concentration, and protein translation appeared suppressed at the high concentration of phenanthrene; most likely in order to reallocate energy budgets for the detoxification process. Finally, an immune response was evoked especially in response to the high effect concentration, which was also described in a previous transcriptomic study using the same effect concentration (EC50) of cadmium. Our study provides new insights in the molecular mode of action of the important polluting class of polycyclic aromatic hydrocarbons in soil animals. Furthermore, we present a fast, sensitive, and specific soil toxicity test which enhances traditional tests and may help to improve current environmental risk assessments and monitoring of potentially polluted sites.
Project description:Polycyclic aromatic hydrocarbons are common pollutants in soil, have negative effects on soil ecosystems, and are potentially carcinogenic. The Springtail (Collembola) Folsomia candida is often used as an indicator species for soil toxicity. Here we report a toxicogenomic study that translates the ecological effects of the polycyclic aromatic hydrocarbon phenanthrene in soil to the early transcriptomic responses in Folsomia candida. Microarrays were used to examine two different exposure concentrations of phenanthrene, namely the EC10 (24.95 mg kg-1 soil) and EC50 (45.80 mg kg-1 soil) on reproduction of this springtail, which evoked 405 and 251 differentially expressed transcripts, respectively. Fifty transcripts were differential in response to either concentration. Many transcripts encoding xenobiotic detoxification and biotransformation enzymes (phases I, II, and III) were upregulated in response to either concentration. Furthermore, indications of general and oxidative stress were found in response to phenanthrene. Chitin metabolism appeared to be disrupted particularly at the low concentration, and protein translation appeared suppressed at the high concentration of phenanthrene; most likely in order to reallocate energy budgets for the detoxification process. Finally, an immune response was evoked especially in response to the high effect concentration, which was also described in a previous transcriptomic study using the same effect concentration (EC50) of cadmium. Our study provides new insights in the molecular mode of action of the important polluting class of polycyclic aromatic hydrocarbons in soil animals. Furthermore, we present a fast, sensitive, and specific soil toxicity test which enhances traditional tests and may help to improve current environmental risk assessments and monitoring of potentially polluted sites. Folsomia candida was exposed to phenanthrene spiked soil or untreated (reference/control) soil for 2 days. Two different concentrations of phenanthrene were used, 24.95 and 45.80 mg/kg soil which represent the EC10 and EC50 on reproduction, respectively. For each concentration treatment 4 biological replicates were used, replicate samples consisted of total RNA extracted from ~30 animals exposed in the same jar to either reference or phenanthrene spiked soil. Phenanthrene treated samples were always hybridized to reference samples in an evenly distributed dye-swap manner, which resulted in total in 8 hybridizations of 16 samples.
Project description:Rhizoremediation, the biotechnology of the utilization of rhizospheric microorganisms associated with plant roots for the elimination of soil contaminants, is based on the ability of microorganisms to metabolize nutrients from plant root exudates, in order to survive the stressful conditions of the rhizosphere, and thereby, to co-metabolize or even mineralize toxic environmental contaminants. Novosphingobium sp. HR1a is a bacterial strain able to degrade a wide variety of polycyclic aromatic hydrocarbons (PAHs). We have demonstrated that this bacterium is able to grow in vegetated microcosms and to eliminate phenanthrene in the presence of clover faster than in non-vegetated systems, establishing a positive interaction with clover. We have studied the molecular basis of this interaction by phenomic, metabolomic and transcriptomic analyses, demonstrating that the positive interaction between clover and Novosphingobium sp. HR1a is a result of the bacterial utilization of different carbon and nitrogen sources (such as sugars, amino acids and organic acids) released during seedling development, and the capacity of exudates to induce the PAH degradation pathway. These results are pointing out to Novosphingobium sp. HR1a as a promising strain for the bioremediation of PAH-contaminated soils.
Project description:Polycyclic Aromatic Hydrocarbons (PAHs) continue to cause environmental challenges due to their release in the environment by a great variety of anthropogenic activities and their accumulation in soil ecosystems. Here we studied the toxicological effect of the model PAH phenanthrene (Phe) on the soil invertebrate model Enchytraeus crypticus at the individual, tissue and molecular level. Organisms were exposed to Phe for 2 and 21 days to the (previously estimated) EC10 and EC50 (population reproduction over 3 weeks). Gene expression profiling did not reveal a typical Phe-induced biotransfor-mation signature, as it usually does in arthropods and vertebrates. Instead, we observed only general metabolic processes to be affected after 2 days of exposure, such as translation and ATP synthesis-coupled electron transport. Histological sections of tissues of 2-day exposed animals did not show any deviations from the control situation. In contrast, prolonged exposure up to 21 days showed histopathological effects: chloragogenous cells were highly vacuolated and hypertrophic. This was corroborated by differential expression of genes related to immune response and oxidative stress at the transcriptomic level. The data exemplify the complexity and species-specific features of PAH toxicity among soil invertebrate communities, which restricts read-across and extrapolation in the context of soil ecological risk assessment.
Project description:Polycyclic Aromatic Hydrocarbons (PAHs) continue to cause environmental challenges due to their release in the environment by a great variety of anthropogenic activities and their accumulation in soil ecosystems. Here we studied the toxicological effect of the model PAH phenanthrene (Phe) on the soil invertebrate model Enchytraeus crypticus at the individual, tissue and molecular level. Organisms were exposed to Phe for 2 and 21 days to the (previously estimated) EC10 and EC50 (population reproduction over 3 weeks). Gene expression profiling did not reveal a typical Phe-induced biotransfor-mation signature, as it usually does in arthropods and vertebrates. Instead, we observed only general metabolic processes to be affected after 2 days of exposure, such as translation and ATP synthesis-coupled electron transport. Histological sections of tissues of 2-day exposed animals did not show any deviations from the control situation. In contrast, prolonged exposure up to 21 days showed histopathological effects: chloragogenous cells were highly vacuolated and hypertrophic. This was corroborated by differential expression of genes related to immune response and oxidative stress at the transcriptomic level. The data exemplify the complexity and species-specific features of PAH toxicity among soil invertebrate communities, which restricts read-across and extrapolation in the context of soil ecological risk assessment. The data presented in our manuscript is an exposure experiment where E. cryticus is exposed to phenanthrene EC10 and EC50 on reproduction for 2 and 21 days. A single channel, interwoven loop design was used to test animals. 4 biological replicates per condition were used containing 25 grams of soil and 5 - 7, adult old animals per replicate. The platform is a 4*180k Agilent platform containing some 86k E. crypticus probes in duplicate. However, only a subset of the probes (23k) was used for the analysis. To see which probes were used in the analysis see the raw data files control type column, only probes which are denoted with a 0 were used.
Project description:To provide a transcriptome resource for identification of transcripts where abundance correlated with developmental changes in willow plantlets derived from bud culture after transfer to soil.