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:Arsenic (As) bioavailability in the rice rhizosphere is influenced by many microbial interactions, particularly by metal-transforming functional groups at the root-soil interface. This study was conducted to examine As-transforming microbes and As-speciation in the rice rhizosphere compartments, in response to two different water management practices (continuous and intermittently flooded), established on fields with high to low soil-As concentration. Microbial functional gene composition in the rhizosphere and root-plaque compartments were characterized using the GeoChip 4.0 microarray. Arsenic speciation and concentrations were analyzed in the rhizosphere soil, root-plaque, porewater and grain samples. Results indicated that intermittent flooding significantly altered As-speciation in the rhizosphere, and reduced methyl-As and AsIII concentrations in the pore water, root-plaque and rice grain. Ordination and taxonomic analysis of detected gene-probes indicated that root-plaque and rhizosphere assembled significantly different metal-transforming functional groups. Taxonomic non-redundancy was evident, suggesting that As-reduction, -oxidation and -methylation processes were performed by different microbial groups. As-transformation was coupled to different biogeochemical cycling processes establishing functional non-redundancy of rice-rhizosphere microbiome in response to both rhizosphere compartmentalization and experimental treatments. This study confirmed diverse As-biotransformation at root-soil interface and provided novel insights on their responses to water management, which can be applied for mitigating As-bioavailability and accumulation in rice grains.
Project description:In the soil the stability of urea is affected by the presence of urease, a ubiquitous enzyme released in the rhizosphere by microbial population and by decomposition of organic matter. To reduce the impact on farmer economies and environmental pollution, a common agronomical practice consists of applying urease inhibitors which delays the hydrolysis of urea and, in turn, ammonia is slowly release in the soil. General aim of the present work was the description of changes in maize root transcriptome occurring in response to treatment with the urease inhibitor NBPT.
Project description:Phosphate (P) fertilization induces a myriad of plant rhizosphere processes, required for a better P plant use. However, extended knowledge about plant responses to polyphosphates (PolyP) is still scarce, particularly transcriptomic and functional traits of root-induced rhizosphere processes. The present study aims to investigate belowground traits related to root transcriptomic changes, rhizosphere acidification, root growth, and P acquisition of durum wheat under PolyPs (PolyB and PolyC) supply. Root molecular traits were differentially expressed in response to PolyPs types, with 2481 and 184 genes were differentially expressed (compared to OrthoP) under PolyB (445 up- and 2036 down-regulated) and PolyC (71 up- and 113 down-regulated), respectively. Specifically, PolyB significantly influenced the expression of genes encoding the key enzymes in glycolysis, citrate cycle and acid phosphatases, OGDH, MDH, and ENO, PAP21 genes were upregulated, while TPI, PFK and LDH genes were downregulated. The modulated expression of TCA cycle and PAP genes can presumably explain the induced rhizosphere acidification (pH decreased from 8 to 6.3) and acid phosphatases activity (in root, rhizosphere soil and rhizosphere soil solution) under PolyPs, which consequently increased rhizosphere soil P availability (145% compared to OrthoP). This increase in P availability was concomitant with the modulation of root morphological traits and the upregulation of the AUX1 and ABA transporters genes, indicating PolyPs regulatory role in root growth for efficient P uptake. Moreover, PolyB significantly upregulated the expression of SPX3, which is indispensable for the absorption and transport of inorganic P to both roots and shoots. This was physiologically reflected by the increased shoot (36%) and root (61%) Pi contents in response to PolyB compared to OrthoP. Taken together, our findings provide novel and consistent evidence that enhanced P acquisition from PolyPs entails coordinated regulation of the expression of genes related to root-rhizosphere processes (rhizosphere acidification and phosphatases exudation) and root morphology, which consequently induces physiological adaptive traits enabling enhanced availability, acquisition of P, and wheat growth performance.
Project description:This data set contains 1376 mass spectrometry reads from root, rhizosphere and leaf sample of Populus Trichocarpa, as well as associated controls. This metabolomics data set was collected as part of a larger campaign which complements the metabolomics data with metagenome sequencing, transcriptomics, and soil measurement data.
Project description:We present metaproteome data from maize rhizosphere from sodic soil. Isolation of proteome from maize rhizosphere collected from Experimental Farm, ICAR-IISS, Mau, India was done with the standardized protocol at our laboratory and metaproteome analysis was done with the standardized pipepline. In total 696 proteins with different functions representing 245 genus and 395 species were identified. The proteome data provides direct evidence on the biological processes in soil ecosystem and is the first reported reference data from maize rhizosphere.
Project description:Microbial communities in the rhizosphere make significant contributions to crop health and nutrient cycling. However, their ability to perform important biogeochemical processes remains uncharacterized. Important functional genes, which characterize the rhizosphere microbial community, were identified to understand metabolic capabilities in the maize rhizosphere using GeoChip 3.0-based functional gene array method. Triplicate samples were taken for both rhizosphere and bulk soil, in which each individual sample was a pool of four plants or soil cores. To determine the abundance of functional genes in the rhizosphere and bulk soils, GeoChip 3.0 was used.
Project description:Microbial communities in the rhizosphere make significant contributions to crop health and nutrient cycling. However, their ability to perform important biogeochemical processes remains uncharacterized. Important functional genes, which characterize the rhizosphere microbial community, were identified to understand metabolic capabilities in the maize rhizosphere using GeoChip 3.0-based functional gene array method. Triplicate samples were taken for both rhizosphere and bulk soil, in which each individual sample was a pool of four plants or soil cores. To determine the abundance of functional genes in the rhizosphere and bulk soils, GeoChip 3.0 was used.
Project description:Root exudates contain specialised metabolites that affect the plant’s root microbiome. How host-specific microbes cope with these bioactive compounds, and how this ability shapes root microbiomes, remains largely unknown. We investigated how maize root bacteria metabolise benzoxazinoids, the main specialised metabolites of maize. Diverse and abundant bacteria metabolised the major compound in the maize rhizosphere MBOA and formed AMPO. AMPO forming bacteria are enriched in the rhizosphere of benzoxazinoid-producing maize and can use MBOA as carbon source. We identified a novel gene cluster associated with AMPO formation in microbacteria. The first gene in this cluster, bxdA encodes a lactonase that converts MBOA to AMPO in vitro. A deletion mutant of the homologous bxdA genes in the genus Sphingobium, does not form AMPO nor is it able to use MBOA as a carbon source. BxdA was identified in different genera of maize root bacteria. Here we show that plant-specialised metabolites select for metabolisation-competent root bacteria. BxdA represents a novel benzoxazinoid metabolisation gene whose carriers successfully colonize the maize rhizosphere and thereby shape the plant’s chemical environmental footprint
Project description:Plants and rhizosphere microbes rely closely on each other, with plants supplying carbon to bacteria in root exudates, and bacteria mobilizing soil-bound phosphate for plant nutrition. When the phosphate supply becomes limiting for plant growth, the composition of root exudation changes, affecting rhizosphere microbial communities and microbially-mediated nutrient fluxes. To evaluate how plant phosphate deprivation affects rhizosphere bacteria, Lolium perenne seedlings were root-inoculated with Pseudomonas aeruginosa 7NR, and grown in axenic microcosms under different phosphate regimes (330 uM vs 3-6 uM phosphate). The effect of biological nutrient limitation was examined by DNA microarray studies of rhizobacterial gene expression.