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: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.
Project description:Gene expression patterns of the plant colonizing bacterium,Pseudomonas putida KT2440 were evaluated as a function of growth in the Arabidopsis thaliana rhizosphere. Gene expression in rhizosphere grown P. putida cells was compared to gene expression in non-rhizosphere grown cells. Keywords: Gene expression
Project description:Increased root H+ secretion is known as a strategy of plant adaption to low phosphorus (P) stress by enhancing mobilization of sparingly soluble P-sources. However, it remains fragmentarywhether enhanced H+ exudation could reconstruct the plant rhizosphere microbial community under low P stress. The present study found that P deficiency led to enhanced H+ exudation from soybean (Glycine max) roots. Three out of all eleven soybean H+-pyrophosphatases (GmVP) geneswere up-regulated by Pi starvation in soybean roots. Among them, GmVP2 showed the highest expression level under low P conditions. Transient expression of a GmVP2-green fluorescent protein chimera in tobacco (Nicotiana tabacum) leaves, and functional characterization of GmVP2 in transgenic soybean hairy roots demonstrated that GmVP2 encoded a plasma membrane transporter that mediated H+ exudation. Meanwhile, GmVP2-overexpression in Arabidopsis thaliana resulted in enhanced root H+ exudation, promoted plant growth, and improved sparingly soluble Ca-P utilization. Overexpression of GmVP2 also changed the rhizospheric microbial community structures, as reflected by a preferential accumulation of acidobacteria in the rhizosphere soils. These results suggested that GmVP2 mediated Pi-starvation responsive H+ exudation,which is not only involved in plant growth and mobilization of sparingly soluble P-sources, but also affects microbial community structures in soils.