scholarly journals Nonnodulating Bradyrhizobium spp. Modulate the Benefits of Legume-Rhizobium Mutualism

2016 ◽  
Vol 82 (17) ◽  
pp. 5259-5268 ◽  
Author(s):  
Kelsey A. Gano-Cohen ◽  
Peter J. Stokes ◽  
Mia A. Blanton ◽  
Camille E. Wendlandt ◽  
Amanda C. Hollowell ◽  
...  
Keyword(s):  
Plant Growth ◽  
Root Nodules ◽  
Experimental Treatment ◽  
Plant Performance ◽  
In Planta ◽  
Content Type ◽  
Fitness Effects ◽  
Native Legume ◽  
Bradyrhizobium Spp ◽  
Soil Interface

ABSTRACTRhizobia are best known for nodulating legume roots and fixing atmospheric nitrogen for the host in exchange for photosynthates. However, the majority of the diverse strains of rhizobia do not form nodules on legumes, often because they lack key loci that are needed to induce nodulation. Nonnodulating rhizobia are robust heterotrophs that can persist in bulk soil, thrive in the rhizosphere, or colonize roots as endophytes, but their role in the legume-rhizobium mutualism remains unclear. Here, we investigated the effects of nonnodulating strains on the nativeAcmispon-Bradyrhizobiummutualism. To examine the effects on both host performance and symbiont fitness, we performed clonal inoculations of diverse nonnodulatingBradyrhizobiumstrains onAcmispon strigosushosts and also coinoculated hosts with mixtures of sympatric nodulating and nonnodulating strains. In isolation, nonnodulatingBradyrhizobiumstrains did not affect plant performance. In most cases, coinoculation of nodulating and nonnodulating strains reduced host performance compared to that of hosts inoculated with only a symbiotic strain. However, coinoculation increased host performance only under one extreme experimental treatment. Nearly all estimates of nodulating strain fitness were reduced in the presence of nonnodulating strains. We discovered that nonnodulating strains were consistently capable of coinfecting legume nodules in the presence of nodulating strains but that the fitness effects of coinfection for hosts and symbionts were negligible. Our data suggest that nonnodulating strains most often attenuate theAcmispon-Bradyrhizobiummutualism and that this occurs via competitive interactions at the root-soil interface as opposed toin planta.IMPORTANCERhizobia are soil bacteria best known for their capacity to form root nodules on legume plants and enhance plant growth through nitrogen fixation. Yet, most rhizobia in soil do not have this capacity, and their effects on this symbiosis are poorly understood. We investigated the effects of diverse nonnodulating rhizobia on a native legume-rhizobium symbiosis. Nonnodulating strains did not affect plant growth in isolation. However, compared to inoculations with symbiotic rhizobia, coinoculations of symbiotic and nonnodulating strains often reduced plant and symbiont fitness. Coinoculation increased host performance only under one extreme treatment. Nonnodulating strains also invaded nodule interiors in the presence of nodulating strains, but this did not affect the fitness of either partner. Our data suggest that nonnodulating strains may be important competitors at the root-soil interface and that their capacity to attenuate this symbiosis should be considered in efforts to use rhizobia as biofertilizers.

Physiological Responses of Amaranthus Cruentus L. to Drought Stress Under Sufficient- and Deficient-Nitrogen Conditions

2021 ◽  
Author(s):  
Inês Cechin ◽  
Laura Prado da Silva ◽  
Elisa Teófilo Ferreira ◽  
Sarah Corrêa Barrochelo ◽  
Fernanda Pereira de Souza Rosa de Melo ◽  
...  
Keyword(s):  
Water Stress ◽  
Plant Growth ◽  
Photosynthetic Pigments ◽  
Dry Matter ◽  
Nitrogen Availability ◽  
Leaf Nitrogen ◽  
Nitrogen Supply ◽  
Plant Performance ◽  
In Planta ◽  
Phenolic Contents

Abstract Water and nitrogen availability are environmental factors that can impair plant growth, and when they are combined their effects can be intensified or reduced. The objective of this study was to analyse the influence of nitrogen availability on the responses of Amaranthus cruentus’s metabolisms to water stress. The plants were cultivated in plastic pots filled with vermiculite and kept under greenhouse conditions and were watered with 70% of full strength nitrogen-free Long Ashton solution, containing 1.97 or 9.88 kg N ha−1 as ammonium nitrate, three times a week. Photosynthetic parameter were evaluated in planta and leaves were harvested for chemical analysis of proline and phenolic contents. Higher nitrogen supply increased the shoot dry matter, photosynthetic pigments, photosynthesis, stomatal conductance, transpiration, total leaf nitrogen, proline, nitrate and ammonium but reduced the concentration of flavonoids and total phenols. Water stress for 6 days did not affect dry matter, photosynthetic pigments, leaf nitrogen, ammonium or specialized metabolites but increased the proline and affected negatively the other variables. The observed interactions between nitrogen and water supply resulted in no alleviation of the negative effects of drought on amaranth. Although the increase in nitrogen supply had benefits on plant performance, it intensified the negative effect of water stress. The study shows the importance of choosing the correct level of nitrogen fertilization in order to obtain satisfactory results in terms of plant growth under drought conditions.

scholarly journals Cooperation, Competition, and Specialized Metabolism in a Simplified Root Nodule Microbiome

mBio ◽  
2020 ◽  
Vol 11 (4) ◽  
Author(s):  
Bridget L. Hansen ◽  
Rita de Cassia Pessotti ◽  
Monika S. Fischer ◽  
Alyssa Collins ◽  
Laila El-Hifnawi ◽  
...  
Keyword(s):  
Potential Role ◽  
Root Nodule ◽  
Root Nodules ◽  
Imaging Mass Spectrometry ◽  
In Planta ◽  
Content Type ◽  
Specialized Metabolites ◽  
Brevibacillus Brevis

ABSTRACT Microbiomes associated with various plant structures often contain members with the potential to make specialized metabolites, e.g., molecules with antibacterial, antifungal, or siderophore activities. However, when and where microbes associated with plants produce specialized metabolites, and the potential role of these molecules in mediating intramicrobiome interactions, is not well understood. Root nodules of legume plants are organs devoted to hosting symbiotic bacteria that fix atmospheric nitrogen and have recently been shown to harbor a relatively simple accessory microbiome containing members with the ability to produce specialized metabolites in vitro. On the basis of these observations, we sought to develop a model nodule microbiome system for evaluating specialized microbial metabolism in planta. Starting with an inoculum derived from field-grown Medicago sativa nodules, serial passaging through gnotobiotic nodules yielded a simplified accessory community composed of four members: Brevibacillus brevis, Paenibacillus sp., Pantoea agglomerans, and Pseudomonas sp. Some members of this community exhibited clear cooperation in planta, while others were antagonistic and capable of disrupting cooperation between other partners. Using matrix-assisted laser desorption ionization–imaging mass spectrometry, we found that metabolites associated with individual taxa had unique distributions, indicating that some members of the nodule community were spatially segregated. Finally, we identified two families of molecules produced by B. brevis in planta as the antibacterial tyrocidines and a novel set of gramicidin-type molecules, which we term the britacidins. Collectively, these results indicate that in addition to nitrogen fixation, legume root nodules are likely also sites of active antimicrobial production.

Bioremediation model of oil-contaminated soil in Lapindo mud using multisymbiotic organism

2020 ◽  
Vol 31 (3) ◽  
pp. 586-601
Author(s):  
Yuni Sri Rahayu
Keyword(s):  
Plant Growth ◽  
Contaminated Soil ◽  
Contaminated Soils ◽  
Plant Biomass ◽  
Root Nodules ◽  
Interaction Pattern ◽  
Total Petroleum Hydrocarbons ◽  
Phosphate Solubilizing Bacteria ◽  
Content Type ◽  
Tripartite Symbiosis

PurposeThe study aimed at developing the bioremediation model of Lapindo mud through multisymbiotic organism.Design/methodology/approachThe research was conducted using completely randomized design. The model plants chosen in this research were soybean. The interaction pattern during the treatment was used to develop the bioremediation model based on the parameters.FindingsThe results showed that there was an effect of the type of organism on the parameters, namely: the growth of plant (biomass, height, length of root, and number of leaves), the biomass of root nodules, the percentage of mycorrhizal infection, the content of water, nitrogen, phosphorus, and total petroleum hydrocarbons (TPHs). There was a pattern of multisymbiotic interaction between each organism and roles of each symbiont in that interaction. Therefore, the plants were capable of surviving in the environment of Sidoarjo Lapindo mud. This pattern can be named as the bioremediation model proposed, which is the analogy of tripartite symbiosis between plants, mycorrhizae, and Rhizobium but also adding plant growth bacteria such as phosphate-solubilizing bacteria and hydrocarbon degradation bacteria. The implementation of this model can be used to treat oil-contaminated soil in order to be used as a plant growth medium.Originality/valuePhytoremediation is a new and promising approach to remove contaminants in the environment but using plants alone for remediation confronts many limitations. Therefore, the application of plant-growth-promoting rhizobia (PGPR) has been extended to remediate contaminated soils in association with plants (Zhuang et al., 2007). The development of the model will use the analogy of tripartite symbiosis between plants, mycorrhizae, and Rhizobium. The developed model will be based on the interaction pattern on each parameters obtained. Bioremediation is chosen because it is considered an effective technique to transform toxic components into less toxic products without disrupting the surrounding environment. Besides, bioremediation is cheaper and environment-friendly because it utilizes microorganisms to clean pollutants from the environment (Nugroho, 2006).

scholarly journals Draft Genome Sequence of the Plant Growth–Promoting Rhizobacterium Acinetobacter radioresistens Strain SA188 Isolated from the Desert Plant Indigofera argentea

2017 ◽  
Vol 5 (9) ◽  
Author(s):  
Feras F. Lafi ◽  
Intikhab Alam ◽  
Ton Bisseling ◽  
Rene Geurts ◽  
Vladimir B. Bajic ◽  
...  
Keyword(s):  
Plant Growth ◽  
Genome Sequence ◽  
Root Nodules ◽  
Draft Genome ◽  
Draft Genome Sequence ◽  
Desert Plant ◽  
Content Type ◽  
Acinetobacter Radioresistens ◽  
Plant Growth Promoting ◽  
Growth Promoting

ABSTRACT Acinetobacter radioresistens strain SA188 is a plant endophytic bacterium, isolated from root nodules of the desert plants Indigofera spp., collected in Jizan, Saudi Arabia. Here, we report the 3.2-Mb draft genome sequence of strain SA188, highlighting characteristic pathways for plant growth–promoting activity and environmental adaptation.

scholarly journals Soybean Root Nodule and Rhizosphere Microbiome: Distribution of Rhizobial and Nonrhizobial Endophytes

2021 ◽  
Vol 87 (10) ◽  
Author(s):  
Parris Mayhood ◽  
Babur S. Mirza
Keyword(s):  
Plant Growth ◽  
Random Process ◽  
Host Plant ◽  
Soil Nitrogen ◽  
Root Nodule ◽  
Root Nodules ◽  
Bacterial Endophytes ◽  
Content Type ◽  
Soybean Root ◽  
Selection Of

ABSTRACT Soybean root nodules are known to contain a high diversity of both rhizobial endophytes and nonrhizobial endophytes (NREs). Nevertheless, the variation of these bacteria among different root nodules within single plants has not been reported. So far, it is unclear whether the selection of NREs among different root nodules within single plants is a random process or is strictly controlled by the host plant to favor a few specific NREs based on their beneficial influence on plant growth. As well, it is also unknown if the relative frequency of NREs within different root nodules is consistent or if it varies based on the location or size of a root nodule. We assessed the microbiomes of 193 individual soybean root nodules from nine plants using high-throughput DNA sequencing. Bradyrhizobium japonicum strains occurred in high abundance in all root nodules despite the presence of other soybean-compatible rhizobia, such as Ensifer, Mesorhizobium, and other species of Bradyrhizobium in soil. Nitrobacter and Tardiphaga were the two nonrhizobial genera that were uniformly detected within almost all root nodules, though they were in low abundance. DNA sequences related to other NREs that have frequently been reported, such as Bacillus, Pseudomonas, Flavobacterium, and Variovorax species, were detected in a few nodules. Unlike for Bradyrhizobium, the low abundance and inconsistent occurrence of previously reported NREs among different root nodules within single plants suggest that these microbes are not preferentially selected as endophytes by host plants and most likely play a limited part in plant growth as endophytes. IMPORTANCE Soybean (Glycine max L.) is a valuable food crop that also contributes significantly to soil nitrogen by developing a symbiotic association with nitrogen-fixing rhizobia. Bacterial endophytes (both rhizobial and nonrhizobial) are considered critical for the growth and resilience of the legume host. In the past, several studies have suggested that the selection of bacterial endophytes within root nodules can be influenced by factors such as soil pH, nutrient availability, host plant genotype, and bacterial diversity in soil. However, the influence of size or location of root nodules on the selection of bacterial endophytes within soybean roots is unknown. It is also unclear whether the selection of nonrhizobial endophytes within different root nodules of a single plant is a random process or is strictly regulated by the host. This information can be useful in identifying potential bacterial species for developing bioinoculants that can enhance plant growth and soil nitrogen.

scholarly journals Draft Genome Sequence of Plant Growth-Promoting Streptomyces sp. Strain SA51, Isolated from Olive Trees

2020 ◽  
Vol 9 (1) ◽  
Author(s):  
Sai Shiva Krishna Prasad Vurukonda ◽  
Mauro Mandrioli ◽  
Greta D’Apice ◽  
Emilio Stefani
Keyword(s):  
Plant Growth ◽  
Genome Sequence ◽  
Draft Genome ◽  
Draft Genome Sequence ◽  
Streptomyces Avermitilis ◽  
In Planta ◽  
Content Type ◽  
Plant Growth Promoting ◽  
Growth Promoting ◽  
Olive Trees

A streptomycete was isolated from the rhizosphere of olive trees in the autumn of 2004. Its molecular characterization showed the presence of metabolic pathways promoting plant growth and additional properties that indicate that this strain is a prospective agent for future biocontrol applications in planta. We report here the draft genome sequence of Streptomyces avermitilis strain SA51.

scholarly journals Protists as main indicators and determinants of plant performance

Microbiome ◽  
2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Sai Guo ◽  
Wu Xiong ◽  
Xinnan Hang ◽  
Zhilei Gao ◽  
Zixuan Jiao ◽  
...  
Keyword(s):  
Plant Growth ◽  
Organic Fertilizer ◽  
Agricultural Practices ◽  
Plant Performance ◽  
Organic Fertilization ◽  
Plant Yield ◽  
Growing Seasons ◽  
Beneficial Microorganisms ◽  
Plant Growth Promoting ◽  
Plant Growth Promoting Microbes

Abstract Background Microbiomes play vital roles in plant health and performance, and the development of plant beneficial microbiomes can be steered by organic fertilizer inputs. Especially well-studied are fertilizer-induced changes on bacteria and fungi and how changes in these groups alter plant performance. However, impacts on protist communities, including their trophic interactions within the microbiome and consequences on plant performance remain largely unknown. Here, we tracked the entire microbiome, including bacteria, fungi, and protists, over six growing seasons of cucumber under different fertilization regimes (conventional, organic, and Trichoderma bio-organic fertilization) and linked microbial data to plant yield to identify plant growth-promoting microbes. Results Yields were higher in the (bio-)organic fertilization treatments. Soil abiotic conditions were altered by the fertilization regime, with the prominent effects coming from the (bio-)organic fertilization treatments. Those treatments also led to the pronounced shifts in protistan communities, especially microbivorous cercozoan protists. We found positive correlations of these protists with plant yield and the density of potentially plant-beneficial microorganisms. We further explored the mechanistic ramifications of these relationships via greenhouse experiments, showing that cercozoan protists can positively impact plant growth, potentially via interactions with plant-beneficial microorganisms including Trichoderma, the biological agent delivered by the bio-fertilizer. Conclusions We show that protists may play central roles in stimulating plant performance through microbiome interactions. Future agricultural practices might aim to specifically enhance plant beneficial protists or apply those protists as novel, sustainable biofertilizers.

scholarly journals Rock-Solubilizing Microbial Inoculums Have Enormous Potential as Ecological Remediation Agents to Promote Plant Growth

Forests ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 357
Author(s):  
Zhaohui Jia ◽  
Miaojing Meng ◽  
Chong Li ◽  
Bo Zhang ◽  
Lu Zhai ◽  
...  
Keyword(s):  
Plant Growth ◽  
Leaf Area ◽  
Ecological Restoration ◽  
Root Nodules ◽  
Robinia Pseudoacacia ◽  
Growth Index ◽  
Nodule Formation ◽  
Bare Rock ◽  
Mining Sites ◽  
Robinia Pseudoacacia L

Anthropogenic overexploitation poses significant threats to the ecosystems that surround mining sites, which also have tremendous negative impacts on human health and society safety. The technological capacity of the ecological restoration of mine sites is imminent, however, it remains a challenge to sustain the green restorative effects of ecological reconstruction. As a promising and environmentally friendly method, the use of microbial technologies to improve existing ecological restoration strategies have shown to be effective. Nonetheless, research into the mechanisms and influences of rock-solubilizing microbial inoculums on plant growth is negligible and the lack of this knowledge inhibits the broader application of this technology. We compared the effects of rock-solubilizing microbial inoculums on two plant species. The results revealed that rock-solubilizing microbial inoculums significantly increased the number of nodules and the total nodule volume of Robinia pseudoacacia L. but not of Lespedeza bicolor Turcz. The reason of the opposite reactions is possibly because the growth of R. pseudoacacia was significantly correlated with nodule formation, whereas L. bicolor’s growth index was more closely related to soil characteristics and if soil nitrogen content was sufficient to support its growth. Further, we found that soil sucrase activity contributed the most to the height of R. pseudoacacia, and the total volume of root nodules contributed most to its ground diameter and leaf area. Differently, we found a high contribution of total soil carbon to seedling height and ground diameter of L. bicolor, and the soil phosphatase activity contributed the most to the L. bicolor’ s leaf area. Our work suggests that the addition of rock-solubilizing microbial inoculums can enhance the supply capacity of soil nutrients and the ability of plants to take up nutrients for the promotion of plant growth. Altogether, our study provides technical support for the practical application of rock-solubilizing microbes on bare rock in the future.

scholarly journals Defects in Mitochondrial and Peroxisomal β-Oxidation Influence Virulence in the Maize Pathogen Ustilago maydis

2012 ◽  
Vol 11 (8) ◽  
pp. 1055-1066 ◽  
Author(s):  
Matthias Kretschmer ◽  
Jana Klose ◽  
James W. Kronstad
Keyword(s):  
Ustilago Maydis ◽  
Short Chain Fatty Acids ◽  
Phytopathogenic Fungi ◽  
Metabolic Adaptation ◽  
In Planta ◽  
Gene Encoding ◽  
Disease Symptoms ◽  
Content Type ◽  
C Terminus ◽  
Fungal Phytopathogens

ABSTRACTAn understanding of metabolic adaptation during the colonization of plants by phytopathogenic fungi is critical for developing strategies to protect crops. Lipids are abundant in plant tissues, and fungal phytopathogens in the phylum basidiomycota possess both peroxisomal and mitochondrial β-oxidation pathways to utilize this potential carbon source. Previously, we demonstrated a role for the peroxisomal β-oxidation enzyme Mfe2 in the filamentous growth, virulence, and sporulation of the maize pathogenUstilago maydis. However,mfe2mutants still caused disease symptoms, thus prompting a more detailed investigation of β-oxidation. We now demonstrate that a defect in thehad1gene encoding hydroxyacyl coenzyme A dehydrogenase for mitochondrial β-oxidation also influences virulence, although its paralog,had2, makes only a minor contribution. Additionally, we identified a gene encoding a polypeptide with similarity to the C terminus of Mfe2 and designated it Mfe2b; this gene makes a contribution to virulence only in the background of anmfe2Δ mutant. We also show that short-chain fatty acids induce cell death inU. maydisand that a block in β-oxidation leads to toxicity, likely because of the accumulation of toxic intermediates. Overall, this study reveals that β-oxidation has a complex influence on the formation of disease symptoms byU. maydisthat includes potential metabolic contributions to proliferationin plantaand an effect on virulence-related morphogenesis.

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