Transcriptome and metabolome analysis support that nitrate primarily promotes N and C metabolism in soybean roots and reduces those in nodules.
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ABSTRACT:
ORGANISM(S): Glycine max
PROVIDER: GSE104582 | GEO | 2018/10/01
REPOSITORIES: GEO
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Project description:Metabolomics and transcriptomics of Bradyrhizobium diazoefficiens-induced root nodules Bradyrhizobium diazoefficiens is a nitrogen-fixing endosymbiont, which can grow inside root-nodule cells of the agriculturally important soybean and other host plants. Our previous studies described B. diazoefficiens host-specific global expression changes occurring during legume infection at the transcript and protein level. In order to further characterize nodule metabolism, we here determine by flow injection -time of flight mass spectrometry analysis the metabolome of i) nodules and roots from four different B. diazoefficiens host plants, ii) soybean nodules harvested at different time points during nodule development, and iii) soybean nodules infected by two strains mutated in key genes for nitrogen fixation, respectively. Ribose (soybean), tartaric acid (mungbean), hydroxybutanoyloxybutanoate (siratro) and catechol (cowpea) were among the metabolites found to be specifically elevated in one of the respective host plants. While the level of C4-dicarboxylic acids decreased during soybean nodule development, we observed an accumulation of trehalose-phosphate at 21 days post infection (dpi). Moreover, nodules from non-nitrogen-fixing bacteroids (nifA and nifH mutants) showed specific metabolic alterations; these were also supported by transcriptomics data that was generated for the two mutant strains and were helpful to separate for some examples the respective bacterial and plant contributions to the metabolic profile. The alterations included signs of nitrogen limitation in both mutants, and an increased level of a phytoalexin in nodules induced by the nifA mutant, suggesting that the tissue of these nodules exhibits defense and stress reactions.
2016-11-28 | GSE79811 | GEO
Project description:The soybean–Bradyrhizobium symbiosis enables symbiotic nitrogen fixation (SNF) within root nodules, reducing reliance on synthetic N fertilizers. However, nitrogen fixation is transient, peaking several weeks after Bradyrhizobium colonization and declining as nodules senesce in coordination with host development. To investigate the regulatory mechanisms governing SNF and senescence, we conducted a temporal transcriptomic analysis of soybean nodules colonized with Bradyrhizobium diazoefficiens USDA110. Weekly nodule samples (2 to 10 weeks postinoculation, wpi) were analyzed using RNA and small RNA sequencing, and acetylene reduction assays assessed nitrogenase activity from 4 to 7 wpi. We identified three major nodule developmental phases: early development (2 to 3 wpi), nitrogen fixation (3 to 8 wpi), and senescence (8 to 10 wpi). Soybean showed extensive transcriptional reprogramming during senescence, whereas Bradyrhizobium underwent major transcriptional shifts early in development before stabilizing during nitrogen fixation. We identified seven soybean genes and several microRNAs as candidate biomarkers of nitrogen fixation, including lipoxygenases (Lox), suggesting roles for oxylipin metabolism. Soy hemoglobin-2 (Hb2), previously classified as nonsymbiotic, was upregulated during senescence, implicating oxidative stress responses within aging nodules. Upregulation of the Bradyrhizobium paa operon and rpoH during senescence suggesting metabolic adaptation for survival beyond symbiosis. Additionally, Bradyrhizobium nif gene expression showed stage-specific regulation, with nifK peaking at 2 wpi, nifD and nifA at 2 and 10 wpi, and nifH, nifW, and nifS at 10 wpi. These findings provide insights into SNF regulation and nodule aging, revealing temporal gene expression patterns that could inform breeding or genetic engineering strategies to enhance nitrogen fixation in soybeans and other legume crops.
2025-12-29 | GSE289665 | GEO
Project description:Legume plants can form root organs called nodules where they house intracellular symbiotic rhizobium bacteria. Within nodule cells, rhizobia differentiate into bacteroids, which fix nitrogen for the benefit of the plant. Depending on the combination of host plants and rhizobial strains, the output of rhizobium-legume interactions is varying from non-fixing associations to symbioses that are highly beneficial for the plant. Bradyrhizobium diazoefficiens USDA110 was isolated as a soybean symbiont but it can also establish a functional symbiotic interaction with Aeschynomene afraspera. In contrast to soybean, A. afraspera triggers terminal bacteroid differentiation, a process involving bacterial cell elongation, polyploidy and membrane permeability leading to loss of bacterial viability while plants increase their symbiotic benefit. A combination of plant metabolomics, bacterial proteomics and transcriptomics along with cytological analyses was used to study the physiology of USDA110 bacteroids in these two host plants. We show that USDA110 establish a poorly efficient symbiosis with A. afraspera, despite the full activation of the bacterial symbiotic program. We found molecular signatures of high level of stress in A. afraspera bacteroids whereas those of terminal bacteroid differentiation were only partially activated. Finally, we show that in A. afraspera, USDA110 bacteroids undergo an atypical terminal differentiation hallmarked by the disconnection of the canonical features of this process. This study pinpoints how a rhizobium strain can adapt its physiology to a new host and cope with terminal differentiation when it did not co-evolve with such a host.
2020-12-11 | GSE163004 | GEO
Project description:To understand the responses of plants to environmental stresses will help mitigate the problems via creating stress-tolerant crop.Whole genome DNA microarrays were used to compare the nodule transcriptome profiling of soybean ‘Williams 82’ grown in vermiculite and subjected to low (0.1 mM; LP) or adequate (2.0 mM; HP) Pi levels. Plants were inoculated with two Bradyrhizobium diazoefficiens strains (USDA110 vs. CB1809), which exhibited contrasting growth and nodulation patterns under LP conditions, with the former model strain displaying a lower Pi-stress acclimatization in combination with the model Williams 82. Affymetrix’s whole Soybean Gene Expression Microarray (66K) was used. Microarrays were used to compare the nodule transcriptomes of the model soybean ‘Williams 82’ plants grown in vermiculite and subjected to low (0.1 mM) or sufficient (2.0 mM) inorganic phosphate levels
2025-10-01 | GSE244933 | GEO
Project description:PhyR is an unusual type of response regulator consisting of a receiver domain and an extracytoplasmic function (ECF) sigma factor-like domain. It was recently described as a master regulator of general stress response in Methylobacterium extorquens. Orthologues of this regulator are present in essentially all free-living Alphaproteobacteria. In most of them, phyR is genetically closely linked to a gene encoding an ECF sigma factor. Here, we investigate the role of these two regulators in the soybean symbiont Bradyrhizobium japonicum USDA110. Using deletion mutants and phenotypic assays, we showed that PhyR and the ECF sigma factor sigma(EcfG) are involved in heat shock and desiccation resistance upon carbon starvation. Both mutants had symbiotic defects on the plant hosts Glycine max (soybean) and Vigna radiata (mungbean). They induced fewer nodules than the wild type and these nodules were smaller, less pigmented, and their specific nitrogenase activity was drastically reduced 2 or 3 weeks after inoculation. Four weeks after infection, soybean nodule development caught up to a large extent whereas most mungbean nodules remained defective even 5 weeks after infection. Remarkably, both mutants triggered aberrant nodules on the different host plants with ectopically emerging roots. Microarray analysis revealed that PhyR and sigma(EcfG) control congruent regulons suggesting both regulators are part of the same signalling cascade. This finding was further substantiated by in vitro protein-protein interaction studies which are in line with a partner-switching mechanism controlling gene regulation triggered by phosphorylation of PhyR. The large number of genes of unknown function present in the PhyR/sigma(EcfG) regulon and the conspicuous symbiotic phenotype suggest that these regulators are involved in the Bradyrhizobium-legume interaction via yet undisclosed mechanisms.
2009-07-01 | GSE15910 | GEO
Project description:Various species of rhizobium establish compatible symbiotic relationships with soybean (Glycine max) leading to the formation of nitrogen-fixing nodules in roots. The formation of functional nodules is mediated through complex developmental and transcriptional reprogramming that involves the activity of thousands of plant genes. However, host transcriptome responses that determine the outcome of the symbiotic interactions leading to the formation of functional or non-functional nodules remain unexplored. In this study, we investigated differential compatibilities between rhizobium strains (Bradyrhizobium diazoefficiens USDA 110Bradyrhizobium sp. strain LVM 105) and cultivated and wild soybeans. The nodulation assays revealed that both USDA 110 and LVM 105 strains effectively nodulate G. soja but only USDA 110 can form symbiotic relationships with Williams 82. RNA-seq data revealed that USDA 110 and LVM 105 induce distinct transcriptome programming in functional mature nodules formed on G. soja roots where genes involved in nucleosome assembly, DNA replication, regulation of cell cycle, and defense responses play key roles. Transcriptome comparison also suggested that activation of genes associated with cell wall biogenesis and organization and defense responses together with downregulation of genes involved in the biosynthesis of isoprenoids and antioxidant stress are associated with the formation of non-functional nodules on Williams 82 roots. Moreover, our analysis implies that increased activity of genes involved in oxygen binding, amino acid transport, and nitrate transport differentiates between fully-developed nodules in cultivated versus wild soybeans.
2024-08-19 | GSE267634 | GEO
Project description:PhyR is an unusual type of response regulator consisting of a receiver domain and an extracytoplasmic function (ECF) sigma factor-like domain. It was recently described as a master regulator of general stress response in Methylobacterium extorquens. Orthologues of this regulator are present in essentially all free-living Alphaproteobacteria. In most of them, phyR is genetically closely linked to a gene encoding an ECF sigma factor. Here, we investigate the role of these two regulators in the soybean symbiont Bradyrhizobium japonicum USDA110. Using deletion mutants and phenotypic assays, we showed that PhyR and the ECF sigma factor sigma(EcfG) are involved in heat shock and desiccation resistance upon carbon starvation. Both mutants had symbiotic defects on the plant hosts Glycine max (soybean) and Vigna radiata (mungbean). They induced fewer nodules than the wild type and these nodules were smaller, less pigmented, and their specific nitrogenase activity was drastically reduced 2 or 3 weeks after inoculation. Four weeks after infection, soybean nodule development caught up to a large extent whereas most mungbean nodules remained defective even 5 weeks after infection. Remarkably, both mutants triggered aberrant nodules on the different host plants with ectopically emerging roots. Microarray analysis revealed that PhyR and sigma(EcfG) control congruent regulons suggesting both regulators are part of the same signalling cascade. This finding was further substantiated by in vitro protein-protein interaction studies which are in line with a partner-switching mechanism controlling gene regulation triggered by phosphorylation of PhyR. The large number of genes of unknown function present in the PhyR/sigma(EcfG) regulon and the conspicuous symbiotic phenotype suggest that these regulators are involved in the Bradyrhizobium-legume interaction via yet undisclosed mechanisms. Comparative analysis of the B. japonicum phyR mutant 8402, ecfG mutant 8404 mutant and the wild type during exponential growth in rich medium (PSY) and after 24 hours starvation in carbon source-free minimal medium
2010-05-16 | E-GEOD-15910 | biostudies-arrayexpress
Project description:part of GSE8478: Genome-wide transcript analysis of Bradyrhizobium japonicum bacteroids in soybean root nodules This SuperSeries is composed of the SubSeries listed below.
2007-11-15 | GSE9100 | GEO
Project description:Bradyrhizobium diazoefficiens can live inside soybean root nodules and in free-living conditions. In both states, when oxygen levels decrease, cells adjust their protein pools by gene transcription modulation. PhaR encodes a transcription factor annotated as PHA (polyhydroxyalkanoate) accumulation regulator. We found that PhaR not only controls the PHA cycle but also acts as a global regulator of excess carbon allocation by controlling the expression of fixK2 and nifA genes, both encoding key transcription factors for microoxic and symbiotic metabolism in B. diazoefficiens. The function of PhaR was expanded by a multi-pronged approach that includes analysis of the effects of phaR mutation at transcriptional and protein levels of putative PhaR targets and direct control mediated by PhaR determined by EMSA assays. We also were able to identify PhaR, phasins and other proteins associated with PHA granules which confirmed a global function of PhaR in microoxia.
2024-05-22 | PXD047760 | Pride
Project description:root nodules induced by Bradyrhizobium diazoefficiens USDA110 and its mutant dSH3_IP Transcriptome
| PRJNA938595 | ENA