Does Rhizobial Inoculation Change the Microbial Community in Field Soils? A‍ ‍Comparison with Agricultural Land-use Changes.

Although microbial inoculation may be effective for sustainable crop production, detrimental aspects have been argued because of the potential of inoculated microorganisms to behave as invaders and negatively affect the microbial ecosystem. We herein compared the impact of rhizobial inoculation on the soil bacterial community with that of agricultural land-use changes using a 16S rRNA amplicon ana-lysis. Soybean plants were cultivated with and without five types of bradyrhizobial inoculants (Bradyrhizobium diazoefficiens or Bradyrhizobium ottawaense) in experimental fields of Andosol, and the high nodule occupancy (35-72%) of bradyrhizobial inoculants was confirmed by nosZ PCR.

Growth and Yield Dynamics in Three Japanese Soybean Cultivars with Plant Growth-Promoting spp. and Co-Inoculation.

Co-inoculation of soybeans with and plant growth-promoting bacteria has displayed promise for enhancing plant growth, but concrete evidence of its impact on soybean yields is limited. Therefore, this study assessed the comparative efficacy of two 1-aminocyclopropane-1-carboxylate deaminase-producing species (OFT2 and OFT5) co-inoculated with (SG09) on the growth, physiology, nodulation efficiency, and grain yield of three major Japanese soybean cultivars: Enrei, Fukuyutaka, and Satonohohoemi. The experiments were conducted in a warehouse under natural light conditions.

Bradyrhizobium ottawaense efficiently reduces nitrous oxide through high nosZ gene expression.

NO is an important greenhouse gas influencing global warming, and agricultural land is the predominant (anthropogenic) source of NO emissions. Here, we report the high NO-reducing activity of Bradyrhizobium ottawaense, suggesting the potential for efficiently mitigating NO emission from agricultural lands. Among the 15 B.

Synergistic N-fixation and salt stress mitigation in soybean through dual inoculation of ACC deaminase-producing Pseudomonas and Bradyrhizobium.

We investigated the potential dual application of two Bradyrhizobium strains (B. diazoefficiens USDA110 and B. ottawaense SG09) and plant growth-promoting bacteria, PGPB (Pseudomonas spp.

Seasonal Shifts in Bacterial Community Structures in the Lateral Root of Sugar Beet Grown in an Andosol Field in Japan.

To investigate functional plant growth-promoting rhizobacteria in sugar beet, seasonal shifts in bacterial community structures in the lateral roots of sugar beet were examined using amplicon sequencing ana-lyses of the 16S rRNA gene. Shannon and Simpson indexes significantly increased between June and July, but did not significantly differ between July and subsequent months (August and September). A weighted UniFrac principal coordinate ana-lysis grouped bacterial samples into four clusters along with PC1 (43.

Mitigation of greenhouse gas emission by nitrogen-fixing bacteria.

Chemical nitrogen fixation by the Haber-Bosch method permitted industrial-scale fertilizer production that supported global population growth, but simultaneously released reactive nitrogen into the environment. This minireview highlights the potential for bacterial nitrogen fixation and mitigation of greenhouse gas (GHG) emissions from soybean and rice fields. Nitrous oxide (N2O), a GHG, is mainly emitted from agricultural use of nitrogen fertilizer and symbiotic nitrogen fixation.

Community Analysis-based Screening of Plant Growth-promoting Bacteria for Sugar Beet.

Clone libraries of bacterial 16S rRNA genes (a total of 1,980 clones) were constructed from the leaf blades, petioles, taproots, and lateral roots of sugar beet (Beta vulgaris L.) grown under different fertilization conditions. A principal coordinate analysis revealed that the structures of bacterial communities in above- and underground tissues were largely separated by PC1 (44.

Strains of sp. nov., isolated from contrasting habitats in Japan and Canada possess photosynthesis gene clusters with the hallmark of genomic islands.

The taxonomic status of two previously characterized strains (58S1 and S23321) isolated from contrasting habitats in Canada and Japan was verified by genomic and phenotypic analyses. Phylogenetic analyses of five and 27 concatenated protein-encoding core gene sequences placed both strains in a highly supported lineage distinct from named species in the genus with as the closest relative. Average nucleotide identity values of genome sequences between the test and reference strains were between 84.

Levels of Periplasmic Nitrate Reductase during Denitrification are Lower in Bradyrhizobium japonicum than in Bradyrhizobium diazoefficiens.

Soybean plants host endosymbiotic dinitrogen (N)-fixing bacteria from the genus Bradyrhizobium. Under oxygen-limiting conditions, Bradyrhizobium diazoefficiens and Bradyrhizobium japonicum perform denitrification by sequentially reducing nitrate (NO) to nitrous oxide (NO) or N. The anaerobic reduction of NO to NO was previously shown to be lower in B.

Diversity of Bradyrhizobium in Non-Leguminous Sorghum Plants: B. ottawaense Isolates Unique in Genes for NO Reductase and Lack of the Type VI Secretion System.

Diverse members of Bradyrhizobium diazoefficiens, B. japonicum, and B. ottawaense were isolated from the roots of field-grown sorghum plants in Fukushima, and classified into "Rhizobia" with nodulated soybeans, "Free-living diazotrophs", and "Non-diazotrophs" by nitrogen fixation and nodulation assays.

Molecular Analyses of the Distribution and Function of Diazotrophic Rhizobia and Methanotrophs in the Tissues and Rhizosphere of Non-Leguminous Plants.

Biological nitrogen fixation (BNF) by plants and its bacterial associations represent an important natural system for capturing atmospheric dinitrogen (N) and processing it into a reactive form of nitrogen through enzymatic reduction. The study of BNF in non-leguminous plants has been difficult compared to nodule-localized BNF in leguminous plants because of the diverse sites of N fixation in non-leguminous plants. Identification of the involved N-fixing bacteria has also been difficult because the major nitrogen fixers were often lost during isolation attempts.

Symbiotic incompatibility between soybean and Bradyrhizobium arises from one amino acid determinant in soybean Rj2 protein.

Cultivated soybean (Glycine max) carrying the Rj2 allele restricts nodulation with specific Bradyrhizobium strains via host immunity, mediated by rhizobial type III secretory protein NopP and the host resistance protein Rj2. Here we found that the single isoleucine residue I490 in Rj2 is required for induction of symbiotic incompatibility. Furthermore, we investigated the geographical distribution of the Rj2-genotype soybean in a large set of germplasm by single nucleotide polymorphism (SNP) genotyping using a SNP marker for I490.

Nitrogen Cycling in Soybean Rhizosphere: Sources and Sinks of Nitrous Oxide (NO).

Nitrous oxide (NO) is the third most important greenhouse gas after carbon dioxide and methane, and a prominent ozone-depleting substance. Agricultural soils are the primary anthropogenic source of NO because of the constant increase in the use of industrial nitrogen (N) fertilizers. The soybean crop is grown on 6% of the world's arable land, and its production is expected to increase rapidly in the future.

Growth Stage-dependent Bacterial Communities in Soybean Plant Tissues: Methylorubrum Transiently Dominated in the Flowering Stage of the Soybean Shoot.

Plant-associated bacteria are critical for plant growth and health. However, the effects of plant growth stages on the bacterial community remain unclear. Analyses of the microbiome associated with field-grown soybean revealed a marked shift in the bacterial community during the growth stages.

Identification of Genes Regulated by the Antitermination Factor NasT during Denitrification in Bradyrhizobium diazoefficiens.

The soybean symbiont Bradyrhizobium diazoefficiens grows anaerobically in the presence of nitrate using the denitrification pathway, which involves the nap, nir, nor, and nos genes. We previously showed that NasT acts as a transcription antitermination regulator for nap and nos gene expression. In the present study, we investigated the targets of NasT in B.

Identification of Nitrogen-Fixing Associated With Roots of Field-Grown Sorghum by Metagenome and Proteome Analyses.

Sorghum () is cultivated worldwide for food, bioethanol, and fodder production. Although nitrogen fixation in sorghum has been studied since the 1970s, N-fixing bacteria have not been widely examined in field-grown sorghum plants because the identification of functional diazotrophs depends on the culture method used. The aim of this study was to identify functional N-fixing bacteria associated with field-grown sorghum by using "omics" approaches.

Mapping of quantitative trait loci related to primary rice root growth as a response to inoculation with sp. strain B510.

sp. strain B510 has been known as the plant growth-promoting endophyte; however, the growth-promotion effect is dependent on the plant genotype. Here, we aimed to identify quantitative trait loci (QTL) related to primary root length in rice at the seedling stage as a response to inoculation with B510.

Publisher Correction: Core microbiomes for sustainable agroecosystems.

Owing to a technical error, this Perspective was originally published without its received and accepted dates; the dates "Received: 31 December 2017; Accepted: 23 March 2018" have now been included in all versions.

Variation in bradyrhizobial NopP effector determines symbiotic incompatibility with Rj2-soybeans via effector-triggered immunity.

Genotype-specific incompatibility in legume-rhizobium symbiosis has been suggested to be controlled by effector-triggered immunity underlying pathogenic host-bacteria interactions. However, the rhizobial determinant interacting with the host resistance protein (e.g.

Involvement of ethylene signaling in Azospirillum sp. B510-induced disease resistance in rice.

Unlabelled: A bacterial endophyte Azospirillum sp. B510 induces systemic disease resistance in the host without accompanying defense-related gene expression. To elucidate molecular mechanism of this induced systemic resistance (ISR), involvement of ethylene (ET) was examined using OsEIN2-knockdown mutant rice.