Project description:Bile acids are steroid compounds from the digestive tracts of vertebrates that enter agricultural environments in unusual high amounts with manure. Bacteria degrading bile acids can readily be isolated from soils and waters including agricultural areas. Under laboratory conditions, these bacteria transiently release steroid compounds as degradation intermediates into the environment. These compounds include androstadienediones (ADDs), which are C19-steroids with potential hormonal effects. Experiments with Caenorhabditis elegans showed that ADDs derived from bacterial bile acid degradation had effects on its tactile response, reproduction rate, and developmental speed. Additional experiments with a deletion mutant as well as transcriptomic analyses revealed that these effects might be conveyed by the putative testosterone receptor NHR-69. Soil microcosms showed that the natural microflora of agricultural soil is readily induced for bile acid degradation accompanied by the transient release of steroid intermediates. Establishment of a model system with a Pseudomonas strain and C. elegans in sand microcosms indicated transient release of ADDs during the course of bile acid degradation and negative effects on the reproduction rate of the nematode. This proof-of-principle study points at bacterial degradation of manure-derived bile acids as a potential and so-far overlooked risk for invertebrates in agricultural soils.
Project description:Some soil bacteria promote plant growth, including Pseudomonas species. With this approach we detected significant changes in Arabidopsis genes related to primary metabolism that were induced by the bacteria.
Project description:Green manure is widely advocated as a sustainable alternative to chemical fertilizers in crop systems, yet the mechanisms underlying its yield benefits remain unclear. Moreover, vigorous vegetative growth under green manure can elevate lodging risk, undermining yield and harvest efficiency. Here, we describe mechanisms by which hairy vetch–based green manure enhances yield and evaluate the practical value of deploying functionally weak alleles of gibberellin 20-oxidase (GA20ox) in this management context. We conducted field comparisons of green manure and conventional chemical fertilization to evaluate effects on rice productivity, grain appearance quality, and canopy physiology. Green manure significantly increased grain yield and grain appearance quality in the leading Japanese cultivar ‘Koshihikari’, accompanied by higher lodging. By contrast, high-yielding cultivars homozygous for a single-copy GA20ox1 allele and/or a non-functional GA20ox2 allele maintained superior lodging resistance under green manure treatment while improving yield and grain appearance quality, indicating an effective combination of its treatment and genotypes. Physiologically, green manure increased chlorophyll index during vegetative growth and at the reproductive stage, and nitrogen (N) concentration on the whole plant. Furthermore, green manure increased flag-leaf width and tiller number; these canopy changes were associated with reduced panicle temperature at the ripening stage. Green manure treatment induced upregulation of OsNADH-GOGAT2, a known gene associated with increased N loading to grains, and more grain storage proteins, providing a positive link to improved grain appearance quality. Collectively, this study demonstrates that integrating hairy vetch with functionally weak GA20ox alleles can enhance productivity and grain appearance quality while mitigating lodging risk. This sheds light on the importance of aligning green-manure treatment with targeted allelic selection to stabilize performance across intensive-farming systems and reduce chemical fertilizer dependency.
Project description:Bacteria belonging to phylum Gemmatimonadetes are found in a wide variety of environments and are particularly abundant in soils. To date, only two Gemmatimonadetes strains have been characterized. Here we report the complete genome sequence and methylation pattern of Gemmatirosa kalamazoonensis KBS708 (ATCC BAA-2150; NCCB 100411), the first characterized Gemmatimondetes strain isolated from soil. Examination of the methylome of Gemmatirosa kalamazoonenis KBS708 using kinetic data from single-molecule, real-time (SMRT) sequencing on the PacBio RS
Project description:Some soil bacteria promote plant growth, including Pseudomonas species. With this approach we detected significant changes in Arabidopsis genes related to primary metabolism that were induced by the bacteria. Pseudomonas G62 was applied to roots of 18 day-old Arabidopsis seedlings and the transcriptional profile of whole seedlings after 6 hours of treatment was analyzed.
Project description:<p>Common vetch (Vicia sativa L.) is an important annual leguminous forage crop commonly used for green manure, fodder, and soil improvement. It is widely cultivated as a green manure and forage crop in Yunnan Province during winter and spring. However, the dry conditions and minimal rainfall during these seasons greatly limit common vetch growth. Therefore, screening for drought-tolerant, high-yielding common vetch varieties is a critical objective in breeding programs.</p>
Project description:In order to get insights into the ability of ectomycorrhizal fungi to perceive their biotic environment as well as into the mechanisms of the interactions between ectomycorrhizal fungi and soil bacteria, we analysed the transcriptomic response of the ectomycorrhizal fungus L. bicolor and of two beneficial, and neutral soil bacteria during their interactions in vitro.
Project description:<p>Background</p><p>Soil salinization and alkalization severely threaten soybean growth and yield. Arbuscular mycorrhizal fungi (AMF), specifically Rhizophagus intraradices (Ri), enhance stress tolerance and soil quality, yet their mechanisms in regulating microbial-metabolite interactions during critical soybean growth stages remain unclear.</p><p>Results</p><p>This research employed partitioned (rhizosphere and hyphosphere) pot experiments in natural saline-alkaline soil, integrating high-throughput sequencing and untargeted metabolomics to analyze Ri effects on microbial communities and metabolic functions at branching (V5), pod development (R4), and mature pod (R8) stages. Results revealed V5 stage for Ri to activate host resistance, R4 for hyphal expansion (density 21.13 m/g), enhancing nutrient uptake, and R8 stage for increased spore and glomalin-related soil protein (GRSP) secretion to alleviate stress. Ri differentially regulates bacterial-fungal networks, enriching biomarker and driving stochastic microbial assembly. Ri shifted bacterial assembly toward stochasticity and enriched biomarkers. Bacterial richness peaked under RiRR4 (+Ri, R4 rhizosphere; +27.06% vs CRR4). Fungal assembly showed a different trend, peaking under RiRV5 (+Ri, V5 rhizosphere; +39.75% vs CRV5). Ri enhanced plant resistance and soybean growth via bacterial diversity in rhizosphere soil. Metabolomics identified phenylalanine metabolism as a core Ri-regulated pathway under saline-alkaline stress, facilitating carbon-nitrogen cycling and secondary metabolite accumulation.</p><p>Conclusions</p><p>This research reveals how Ri coordinates microbial and metabolic processes to enhance saline-alkaline resistance in soybean.</p>