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:RHIZOSPHERE SOIL PHOSPHORUS AND DROUGHT-TOLERANT BACTERIA
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:To identify novel microRNAs that are associated with drought tolerance in two different cowpea genotypes, we generated small RNA sequences from adult cowpea plants under control and dought stress treatments. Over 79 million raw reads were generated and numerous novel microRNAs are identified, including some associated with drought tolerance.
Project description:Understanding the environmental factors that shape microbial communities is crucial, especially in extreme environments, like Antarctica. Two main forces were reported to influence Antarctic soil microbes: birds and plants. Both birds and plants are currently undergoing unprecedented changes in their distribution and abundance due to global warming. However, we need to clearly understand the relationship between plants, birds and soil microorganisms. We therefore collected rhizosphere and bulk soils from six different sampling sites subjected to different levels of bird influence and colonized by Colobanthus quitensis and Deschampsia antarctica in the Admiralty Bay, King George Island, Maritime Antarctic. Microarray and qPCR assays targeting 16S rRNA genes of specific taxa were used to assess microbial community structure, composition and abundance and analyzed with a range of soil physico-chemical parameters. The results indicated significant rhizosphere effects in four out of the six sites, including areas with different levels of bird influence. Acidobacteria were significantly more abundant in soils with little bird influence (low nitrogen) and in bulk soil. In contrast, Actinobacteria were significantly more abundant in the rhizosphere of both plant species. At two of the sampling sites under strong bird influence (penguin colonies), Firmicutes were significantly more abundant in D. antarctica rhizosphere but not in C. quitensis rhizosphere. The Firmicutes were also positively and significantly correlated to the nitrogen concentrations in the soil. We conclude that the microbial communities in Antarctic soils are driven both by bird and plants, and that the effect is taxa-specific.
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.
Project description:To identify novel microRNAs that are associated with drought tolerance in two different cowpea genotypes, we generated small RNA sequences from adult cowpea plants under control and dought stress treatments. Over 79 million raw reads were generated and numerous novel microRNAs are identified, including some associated with drought tolerance. Sequencing of small RNAs in two cowpea genotypes under control and drought stress conditions.