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:Medicago truncatula engages in root nodule symbiosis by developing a de novo plant organ (known as nodule) in its roots in response to the infection by rhizobia. These nodules are de novo plant organs that provide an optimal environment for the rhizobia to fix nitrogen in exchange for photosynthates. The establishment of root nodule symbioses (RNS) requires the coordination of two distinct processes: bacterial infection and nodule organogenesis. In this study we used single-cell RNA-seq to investigate the first hours of the establishment of the root nodule symbiosis aiming to identify the transcriptional mechanisms governing this process.
Project description:The ability of chickpea to obtain sufficient nitrogen via its symbiotic relationship with Mesorhizobium ciceri is of critical importance in supporting growth and grain production. A number of factors can affect this symbiotic relationship including abiotic conditions, plant genotype, and disruptions to host signalling/perception networks. In order to support improved nodule formation in chickpea, we investigated how plant genotype and soil nutrient availability affect chickpea nodule formation and nitrogen fixation. Further, using transcriptomic profiling, we sought to identify gene expression patterns that characterize highly nodulated genotypes.
Project description:Legumes establish endosymbiotic associations with nitrogen-fixing rhizobia, which they host inside root nodules. Here, specific physiological and morphological adaptations, such as the production of oxygen-binding leghemoglobin proteins and the formation of an oxygen diffusion barrier in the nodule periphery, are essential to protect the oxygen-labile bacterial nitrogenase enzyme. The molecular basis of the latter process remains elusive, as the identification of required genes is limited by the epistatic effect of nodule organogenesis over nodule infection and rhizobia accommodation. We overcame this by exploring the phenotypic diversity of Lotus japonicus accessions that uncouple nodule organogenesis from nodule infection when inoculated with a sub-compatible Rhizobium strain. Using comparative transcriptomics, we identified genes with functions associated with oxygen homeostasis and deposition of lipid polyesters on cell walls to be specifically upregulated in infected compared to uninfected nodules. As such hydrophobic modifications on cell walls are pivotal for creating diffusion barriers like the root endodermis, we focused on two Fatty acyl-CoA reductase genes that were specifically activated in the nodule or in the root endodermis. Mutant lines in a Fatty acyl-CoA reductase gene expressed exclusively in the nodule endodermis showed had decreased suberization of this cell layer and increased nodule permeability compared to wild type plants. Oxygen concentrations were significantly increased in the inner cortex of mutant nodules, which correlated with reduced nitrogen fixation rates, and impaired shoot growth. These results provide the first genetic evidence for the formation of the nodule oxygen diffusion barrier, a key adaptation enabling nitrogen fixation in legume nodules.
2022-11-01 | GSE216502 | GEO
Project description:Chickpea Root Nodule microRNA and PARE Libraries
Project description:Rhizosphere is a complex system of interactions between plant roots, bacteria, fungi and animals, where the release of plant root exudates stimulates bacterial density and diversity. However, the majority of the bacteria in soil results to be unculturable but active. The aim of the present work was to characterize the microbial community associated to the root of V. vinifera cv. Pinot Noir not only under a taxonomic perspective, but also under a functional point of view, using a metaproteome approach. Our results underlined the difference between the metagenomic and metaproteomic approach and the large potentiality of proteomics in describing the environmental bacterial community and its activity. In fact, by this approach, that allows to investigate the mechanisms occurring in the rhizosphere, we showed that bacteria belonging to Streptomyces, Bacillus and Pseudomonas genera are the most active in protein expression. In the rhizosphere, the identified genera were involved mainly in phosphorus and nitrogen soil metabolism.
2022-02-28 | PXD007670 | Pride
Project description:Bacterial diversity in the root nodules and rhizosphere of chickpea (Cicer arietinum L.)
Project description:Forming symbiotic associations with beneficial microbes are important strategies for sessile plants to acquire nitrogen and phosphorus nutrients from the soil. Root exudates play key roles on set-up of the rhizosphere microbiome. According to the needs for nitrogen or phosphorus, plants can adjust the root exudates composition to attract proper microbes. Flavonoids are a group of secondary metabolites that are well studied in shaping the root microbiome, especially the root nodule symbiosis in legumes. Here, we show the medicago truncatula phosphate sensors SPX1 and SPX3 regulate flavonoids biosynthesis to recruit nitrogen-fixing microbes for nitrogen acquisition. Nitrogen-fixing microbes were less recruited in spx1spx3 double mutant root rhizosphere. This was caused by lower flavonoids biosynthesis related genes expression, which resulted in lower flavonoids levels in the root exudates compared to wild type plant R108. Further analysis indicates the regulation of flavonoids biosynthesis is through the SPX1 and SPX3 interaction transcription factor PHR2. We propose the SPX-PHR phosphate homeostasis regulation network also control microbe-dependent nitrogen acquisition according to phosphate levels. Thus, SPX1 and SPX3 play important roles to keep a microbe-dependent nitrogen and phosphorus absorption balance for optimal growth.
2025-02-28 | GSE289310 | GEO
Project description:Bacterial diversity of nodule and rhizosphere of mungbean
| PRJNA340941 | ENA
Project description:Diazotrophic Bacterial diversity in the root nodules and rhizosphere of chickpea (Cicer arietinum L.)