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:Transcriptomes analysis of the petals from a red-flowered white clover mutant (red flowers) and its shade-treated counterpart (white flowers) grown under shaded conditions was performed using high-throughput sequencing. We obtained 121,626,564 and 130,577,944 clean reads in red-flowered mutant and treated counterpart, respectively. Of these clean reads, we respectively gained 125,350 and 99,638 unigene sequencces in two groups. As a result, a total of 157,964 unigenes were obtained with an average length of 728 bp and a median length of 1346 bp. These findings provideed insights into the expression profiles in red-flowered white clover mutant, and deepened our understanding of flower pigmentation in white clower.
Project description:White clover mosaic virus (WCMV) is a major pathogen of white clover (Trifolium repens L.), with significant effects on yield and persistence. Due to the absence of natural sources of WCMV resistance a transgenic strategy has been employed to produce plants constitutively expressing WCMV replicase gene derivatives, designed to inhibit the propagation of WCMV through an RNA silencing mechanism. A 12,000 feature oligonucleotide microarray has been used to identify global changes in host plant, in addition to virus genome-encoded gene expression associated with WCMV infection in non-transgenic and transgenic WCMV-resistant white clover. Pairwise comparison between the transcriptome of mock-inoculated non-transgenic and WCMV-inoculated transgenic plants provides clear evidence for substantial equivalence between these two genotype/treatments, and demonstrate the efficacy of the transgenic strategy. WCMV- inoculated non-transgenic plants exhibit elevated abundance of many virus-encoded, and host immune response-specific transcripts compared to the transgenic resistant plants or mock-inoculated non-transgenic plants. By contrast, relative to inoculated sensitive plants, the majority of significantly up-regulated genes in mock-inoculated non-transgenic plants or WCMV-inoculated transgenic plants are markers of healthy cellular function. These results, and the occurrence of levels of WCMV-encoded transcripts in inoculated transgenic plants equivalent to those in virus-free plants, confirm the validity of the transgenic RNA silencing approach.<br>
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:The fate of the carbon stocked in permafrost soils following global warming and permafrost thaw is of major concern in view of the potential for increased CH4 and CO2 emissions from these soils. Complex carbon compound degradation and greenhouse gas emissions are due to soil microbial communities, but their composition and functional potential in permafrost soils are largely unknown. Here, a 2 m deep permafrost and its overlying active layer soil were subjected to metagenome sequencing, quantitative PCR, and microarray analyses. The active layer soil and 2 m permafrost soil microbial community structures were very similar, with Actinobacteria being the dominant phylum. The two soils also possessed a highly similar spectrum of functional genes, especially when compared to other already published metagenomes. Key genes related to methane generation, methane oxidation and organic matter degradation were highly diverse for both soils in the metagenomic libraries and some (e.g. pmoA) showed relatively high abundance in qPCR assays. Genes related to nitrogen fixation and ammonia oxidation, which could have important roles following climatic change in these nitrogen-limited environments, showed low diversity but high abundance. The 2 m permafrost soil showed lower abundance and diversity for all the assessed genes and taxa. Experimental biases were also evaluated and showed that the whole community genome amplification technique used caused large representational biases in the metagenomic libraries. This study described for the first time the detailed functional potential of permafrost-affected soils and detected several genes and microorganisms that could have crucial importance following permafrost thaw. A 2m deep permafrost sample and it overlying active layer were sampled and their metagenome analysed. For microarray analyses, 8 other soil samples from the same region were used for comparison purposes.