Project description:The rapid expansion of fast-growing plantations in subtropical regions is closely linked to dry-season irrigation and fertilization; however, improper practices often lead to soil acidification and reduced nutrient bioavailability. Phosphorus (P), one of the most critical elements for plantation tree growth, shows complex spatial distribution patterns in soil that are influenced by multiple factors, directly affecting plantation productivity. This study investigated the effects of long-term fertilization and dry-season irrigation on the vertical distribution of phosphorus in an 8-year-old subtropical Eucalyptus plantation. This study employed stratified sampling (0–30 cm topsoil, 30–60 cm subsoil, 60–90 cm substratum) during dry seasons, coupled with metagenomics, metabolomics, and environmental factor analysis, to reveal vertical phosphorus cycling patterns and multiomics regulatory networks. Key findings: (1) Fertilization and dry-season irrigation had a limited influence on labile phosphorus and the diversity of P-cycling microorganisms. The topsoil presented significantly greater P availability than did the subsoil, manifested as elevated acid phosphatase activity (ACP), significant enrichment of the tryptophan metabolic pathway, and greater microbial diversity. (2) pH and the C:P ratio represent critical factors of vertical stratification in soil P cycling. Under acidic conditions, topsoil microorganisms facilitate P release via diverse metabolic pathways, whereas oligotrophic constraints in the substratum limit enzymatic activities. (3) We believe that potential cross-stratum microbial functional coordination exists in acidic soil P cycling, with linkages to tryptophan metabolism and polyP synthesis/degradation. Our study provides theoretical multiomics insights for optimizing the management of soil P pools in subtropical plantations under fertilization and dry-season irrigation.
Project description:Soil microorganisms carry out decomposition of complex organic carbon molecules, such as chitin. High diversity of the soil microbiome and complexity of the soil habitat has posed a challenge to elucidate specific interactions between soil microorganisms. Here, we overcame this challenge by studying a model soil consortium (MSC-2) that is composed of 8 species. The MSC-2 isolates were originally obtained from the same soil that was enriched with chitin as a substrate. Our aim was to elucidate specific roles of the 8 member species during chitin metabolism in soil. The 8 species were added to sterile soil with chitin and incubated for 3 months. Multi-omics was used to understand how the community composition, transcript and protein expression and chitin-related metabolites shifted during the incubation period. The data clearly and consistently revealed a temporal shift during chitin decomposition and defined contributions by individual species. A Streptomyces species was a key player in early steps of chitin decomposition, followed by other members of MSC-2. These results illustrate how multi-omics applied to a defined consortium untangles complex interactions between soil microorganisms.
Project description:<p>Carbonate-type saline-alkaline stress severely constrains maize production; however, the synergistic response mechanisms between rhizosphere microorganisms and metabolites remain unclear. This study focused on maize fields in the carbonate chernozem region of the Songnen Plain in Northeast China. Through field experiments and the integration of soil chemical factor analysis, microbial high-throughput sequencing (16S rRNA and ITS), and non-targeted metabolomics (LC-MS), we systematically investigated the response mechanisms of the rhizosphere micro-ecosystem under saline-alkaline stress. The results indicated that saline-alkaline stress significantly increased soil pH and electrical conductivity (EC), and led to decreases in soil organic matter (SOM), total nitrogen (TN), and total phosphorus (TP) contents. However, the rhizosphere zone exhibited a certain buffering capacity, maintaining a higher cation exchange capacity (CEC). Microbial community analysis revealed that bacterial alpha diversity increased under stress. In contrast, fungal diversity significantly decreased, and the community structure shifted towards a pathogen-dominated community, primarily within Ascomycota, especially the genus Fusarium. Co-occurrence network analysis further revealed that saline-alkaline conditions enhanced the complexity and connectivity of bacterial networks but led to the contraction and structural simplification of fungal networks. Metabolite analysis showed that saline-alkaline stress induced significant reprogramming of the rhizosphere metabolic profile. Organophosphorus compounds, nucleotides, and their analogs were significantly enriched, while defensive secondary metabolites such as Cajanol specifically accumulated in the saline-alkaline rhizosphere. Pathway analysis indicated the activation of stress resistance and oxidative stress mitigation-related pathways, including Betalain biosynthesis, flavonoid biosynthesis, tryptophan metabolism, and arginine metabolism. Multi-omics integration analysis identified soil EC and total potassium (TK) as key environmental factors driving the differentiation of microbial and metabolite communities. Key differential metabolites showed significant positive correlations with saline-alkaline-enriched microbial taxa (e.g., Sphingomonas), revealing a metabolite-mediated microbial recruitment mechanism. This study, through multi-omics analysis, discovered that the maize rhizosphere, under saline-alkaline stress, undergoes metabolic reprogramming (e.g., enriching defensive metabolites like Cajanol) to directionally recruit beneficial bacteria such as Sphingomonas and maintains higher bacterial network complexity, while also leading to the pathologization of the fungal community. Our study reveals that maize recruits beneficial microbes via rhizosphere metabolic reprogramming, providing a mechanistic basis for microbiome-assisted saline-alkaline soil remediation.</p>
Project description:Anthropogenic nutrient inputs alter soil biodiversity; however, it remains largely unknown whether changes in soil microeukaryotes (fungi and protists) are primarily driven by direct effects, such as modifications in soil properties, or by indirect effects, such as plant diversity loss. To disentangle these mechanisms, we investigated the long-term effects (11 years) of fertilization and manipulated plant diversity (1, 2, or 4 plant species) on soil microeukaryote communities in a temperate grassland experiment using long-amplicon rRNA sequencing. Our results indicate that fertilization generally had a stronger influence on microeukaryote communities than plant species richness. Fertilization altered the community composition of fungi and protists, increased OTU richness by 20.8% and 52.7%, respectively, and shifted community dominance from fungi to protists. Regarding plant diversity, we observed an effect exclusively on the protist community. Changes were primarily explained by increased plant biomass (driven by both fertilization and plant diversity) and by higher soil phosphorus and lower soil pH levels (driven exclusively by fertilization). Regarding life strategies, we observed synergistic treatment effects: fertilization primarily enhanced fungal saprophytes (only richness), fungal animal pathogens, and protist consumers, whereas plant diversity affected phototrophic protists (reduction) and protist animal pathogens (enhancement). Notably, fertilization and plant diversity decline together led to a cumulative increase in fungal plant pathogens. In conclusion, we highlight that fertilisation alone has a significant effect on soil microeukaryotes, while the additional decline in plant diversity affects different soil groups that are not directly affected by fertilisation. This synergistic pattern indicates that fertilization can influence the entire microeukaryote community through direct and indirect mechanisms, with a cumulative enhancement on certain groups, such as plant pathogens.
Project description:Soil transplant serves as a proxy to simulate climate change in realistic climate regimes. Here, we assessed the effects of climate warming and cooling on soil microbial communities, which are key drivers in Earth’s biogeochemical cycles, four years after soil transplant over large transects from northern (N site) to central (NC site) and southern China (NS site) and vice versa. Four years after soil transplant, soil nitrogen components, microbial biomass, community phylogenetic and functional structures were altered. Microbial functional diversity, measured by a metagenomic tool named GeoChip, and phylogenetic diversity are increased with temperature, while microbial biomass were similar or decreased. Nevertheless, the effects of climate change was overridden by maize cropping, underscoring the need to disentangle them in research. Mantel tests and canonical correspondence analysis (CCA) demonstrated that vegetation, climatic factors (e.g., temperature and precipitation), soil nitrogen components and CO2 efflux were significantly correlated to the microbial community composition. Further investigation unveiled strong correlations between carbon cycling genes and CO2 efflux in bare soil but not cropped soil, and between nitrogen cycling genes and nitrification, which provides mechanistic understanding of these microbe-mediated processes and empowers an interesting possibility of incorporating bacterial gene abundance in greenhouse gas emission modeling.
Project description:Expression profiling analyses for 5 maize inbreds and 4 hybrids, chosen to represent diversity in genotypes and heterosis responses, revealed a correlation between genetic diversity and transcriptional variation. This is a companion dataset to an Affymetrix profiling experiment (GEO Series GSE10236). Keywords: Genotype comparison series
Project description:Because of severe abiotic limitations, Antarctic soils represent simplified ecosystems, where microorganisms are the principle drivers of nutrient cycling. This relative simplicity makes these ecosystems particularly vulnerable to perturbations, like global warming, and the Antarctic Peninsula is among the most rapidly warming regions on the planet. However, the consequences of the ongoing warming of Antarctica on microorganisms and the processes they mediate are unknown. Here, using 16S rRNA gene pyrosequencing and qPCR, we report a number of highly consistent changes in microbial community structure and abundance across very disparate sub-Antarctic and Antarctic environments following three years of experimental field warming (+ 0.5-2°C). Specifically, we found significant increases in the abundance of fungi and bacteria and in the Alphaproteobacteria-to-Acidobacteria ratio. These alterations were linked to a significant increase in soil respiration. Furthermore, the shifts toward generalist or opportunistic bacterial communities following warming weakened the linkage between bacterial diversity and functional diversity. Warming also increased the abundance of some organisms related to the N-cycle, detected as an increase in the relative abundance of nitrogenase genes via GeoChip microarray analyses. Our results demonstrate that soil microorganisms across a range of sub-Antarctic and Antarctic environments can respond consistently and rapidly to increasing temperatures, thereby potentially disrupting soil functioning.
Project description:Soil transplant serves as a proxy to simulate climate change in realistic climate regimes. Here, we assessed the effects of climate warming and cooling on soil microbial communities, which are key drivers in EarthM-bM-^@M-^Ys biogeochemical cycles, four years after soil transplant over large transects from northern (N site) to central (NC site) and southern China (NS site) and vice versa. Four years after soil transplant, soil nitrogen components, microbial biomass, community phylogenetic and functional structures were altered. Microbial functional diversity, measured by a metagenomic tool named GeoChip, and phylogenetic diversity are increased with temperature, while microbial biomass were similar or decreased. Nevertheless, the effects of climate change was overridden by maize cropping, underscoring the need to disentangle them in research. Mantel tests and canonical correspondence analysis (CCA) demonstrated that vegetation, climatic factors (e.g., temperature and precipitation), soil nitrogen components and CO2 efflux were significantly correlated to the microbial community composition. Further investigation unveiled strong correlations between carbon cycling genes and CO2 efflux in bare soil but not cropped soil, and between nitrogen cycling genes and nitrification, which provides mechanistic understanding of these microbe-mediated processes and empowers an interesting possibility of incorporating bacterial gene abundance in greenhouse gas emission modeling. Fifty four samples were collected from three soil types (Phaeozem,Cambisol,Acrisol) in three sites (Hailun, Fengqiu and Yingtan) along a latitude with reciprocal transplant; Both with and without maize cropping in each site; Three replicates in every treatments.