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Nakei MD, Venkataramana PB, Ndakidemi PA. Preliminary symbiotic performance of indigenous soybean (Glycine max)-nodulating rhizobia from agricultural soils of Tanzania. FRONTIERS IN SUSTAINABLE FOOD SYSTEMS 2023. [DOI: 10.3389/fsufs.2022.1085843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Globally, the increase in human population continues to threaten the sustainability of agricultural systems. Despite the fast-growing population in Sub-Saharan Africa (SSA) and the efforts in improving the productivity of crops, the increase in the yield of crops per unit area is still not promising. The productivity of crops is primarily constrained by inadequate levels of soil nutrients to support optimum crop growth and development. However, smallholder farmers occasionally use fertilizers, and the amount applied is usually small and does not meet plant requirements. This is due to the unaffordability of the cost of fertilizers, which is enough to suffice the crop requirement. Therefore, there is a need for alternative affordable and effective fertilization methods for sustainable intensification and improvement of the smallholder farming system's productivity. This study was designed to evaluate the symbiotic performance of indigenous soybean nodulating rhizobia in selected agricultural soils of Tanzania. In total, 217 rhizobia isolates were obtained from three agroecological zones, i.e., eastern, northern, and southern highlands. The isolates collected were screened for N2 fixing abilities under in vitro (nitrogen-free medium) and screen house conditions. The results showed varying capabilities of isolates in nitrogen-fixing both under in vitro and screen house conditions. Under in vitro experiment, 22% of soybean rhizobia isolates were identified to have a nitrogen-fixing capability on an N-free medium, with the highest N2-fixing diameter of 1.87 cm. In the screen house pot experiment, results showed that soybean rhizobia isolate significantly (P < 0.001) influenced different plant growth and yield components, where the average shoot dry weight ranged from 2.49 to 10.98 g, shoot length from 41 to 125.27 cm whilst the number of leaves per plant ranged from 20 to 66. Furthermore, rhizobia isolates significantly (P = 0.038) increased root dry weight from 0.574 to 2.17 g. In the case of symbiotic parameters per plant, the number of nodules was in the range of 0.33–22, nodules dry weight (0.001–0.137 g), shoot nitrogen (2.37–4.97%), total nitrogen (53.59–6.72 g), and fixed nitrogen (46.878–0.15 g) per plant. In addition, the results indicated that 51.39% of the tested bacterial isolates in this study were ranked as highly effective in symbiosis, suggesting that they are promising as potential alternative biofertilizers for soybean production in agricultural soils of Tanzania to increase productivity per unit area while reducing production cost.
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de Moura GGD, de Barros AV, Machado F, da Silva Dambroz CM, Glienke C, Petters-Vandresen DAL, Alves E, Schwan RF, Pasqual M, Dória J. The Friend Within: Endophytic Bacteria as a Tool for Sustainability in Strawberry Crops. Microorganisms 2022; 10:microorganisms10122341. [PMID: 36557594 PMCID: PMC9780916 DOI: 10.3390/microorganisms10122341] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 10/05/2022] [Accepted: 10/21/2022] [Indexed: 11/29/2022] Open
Abstract
Strawberry (Fragaria x ananassa, Duch.) is an important crop worldwide. However, since it is a highly demanding crop in terms of the chemical conditions of the substrate, a large part of strawberry production implies the application of large amounts of fertilizers in the production fields. This practice can cause environmental problems, in addition to increases in the fruit's production costs. In this context, applying plant growth-promoting bacteria in production fields can be an essential strategy, especially thanks to their ability to stimulate plant growth via different mechanisms. Therefore, this study aimed to test in vitro and in vivo the potential of bacteria isolated from strawberry leaves and roots to directly promote plant growth. The isolates were tested in vitro for their ability to produce auxins, solubilize phosphate and fix nitrogen. Isolates selected in vitro were tested on strawberry plants to promote plant growth and increase the accumulation of nitrogen and phosphorus in the leaves. The tested isolates showed an effect on plant growth according to biometric parameters. Among the tested isolates, more expressive results for the studied variables were observed with the inoculation of the isolate MET12M2, belonging to the species Brevibacillus fluminis. In general, bacterial inoculation induced strain-dependent effects on strawberry growth. In vitro and in vivo assays showed the potential use of the B. fluminis MET12M2 isolate as a growth promoter for strawberries.
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Affiliation(s)
| | | | - Franklin Machado
- Phytopathology Department, Federal University of Viçosa, Viçosa 36570-900, Brazil
| | | | - Chirlei Glienke
- Genetic Department, Federal University of Paraná, Curitiba 81531-980, Brazil
| | | | - Eduardo Alves
- Phytopathology Department, Federal University of Lavras, Lavras 37200-900, Brazil
| | | | - Moacir Pasqual
- Agriculture Department, Federal University of Lavras, Lavras 37200-900, Brazil
| | - Joyce Dória
- Agriculture Department, Federal University of Lavras, Lavras 37200-900, Brazil
- Correspondence:
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Hernández-Reyes C, Lichtenberg E, Keller J, Delaux PM, Ott T, Schenk ST. NIN-Like Proteins: Interesting Players in Rhizobia-Induced Nitrate Signaling Response During Interaction with Non-Legume Host Arabidopsis thaliana. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2022; 35:230-243. [PMID: 34813707 DOI: 10.1094/mpmi-10-21-0261-r] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Nitrogen is an essential macronutrient and a key cellular messenger. Plants have evolved refined molecular systems to sense the cellular nitrogen status. This is exemplified by the root nodule symbiosis between legumes and symbiotic rhizobia, where nitrate availability inhibits this mutualistic interaction. Additionally, nitrate also functions as a metabolic messenger, resulting in nitrate signaling cascades which intensively crosstalk with other physiological pathways. Nodule inception-like proteins (NLPs) are key players in nitrate signaling and regulate nitrate-dependent transcription during legume-rhizobia interactions. Nevertheless, the coordinated interplay between nitrate signaling pathways and rhizobacteria-induced responses remains to be elucidated. In our study, we investigated rhizobia-induced changes in the root system architecture of the non-legume host arabidopsis under different nitrate conditions. We demonstrate that rhizobium-induced lateral root growth and increased root hair length and density are regulated by a nitrate-related signaling pathway. Key players in this process are AtNLP4 and AtNLP5, because the corresponding mutants failed to respond to rhizobia. At the cellular level, AtNLP4 and AtNLP5 control a rhizobia-induced decrease in cell elongation rates, while additional cell divisions occurred independently of AtNLP4. In summary, our data suggest that root morphological responses to rhizobia are coordinated by a newly considered nitrate-related NLP pathway that is evolutionarily linked to regulatory circuits described in legumes.[Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.
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Affiliation(s)
- Casandra Hernández-Reyes
- Cell Biology, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
- CIBSS-Centre of Integrative Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
| | | | - Jean Keller
- Laboratoire de Recherche en Sciences Végétales, Université de Toulouse, Centre National de la Recherche Scientifique, Université Paul Sabatier, INP Toulouse, 31326 Castanet Tolosan, France
| | - Pierre-Marc Delaux
- Laboratoire de Recherche en Sciences Végétales, Université de Toulouse, Centre National de la Recherche Scientifique, Université Paul Sabatier, INP Toulouse, 31326 Castanet Tolosan, France
| | - Thomas Ott
- Cell Biology, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
- CIBSS-Centre of Integrative Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Sebastian T Schenk
- Cell Biology, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
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Mukherjee A. What do we know from the transcriptomic studies investigating the interactions between plants and plant growth-promoting bacteria? FRONTIERS IN PLANT SCIENCE 2022; 13:997308. [PMID: 36186072 PMCID: PMC9521398 DOI: 10.3389/fpls.2022.997308] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 09/02/2022] [Indexed: 05/21/2023]
Abstract
Major crops such as corn, wheat, and rice can benefit from interactions with various plant growth-promoting bacteria (PGPB). Naturally, several studies have investigated the primary mechanisms by which these PGPB promote plant growth. These mechanisms involve biological nitrogen fixation, phytohormone synthesis, protection against biotic and abiotic stresses, etc. Decades of genetic and biochemical studies in the legume-rhizobia symbiosis and arbuscular mycorrhizal symbiosis have identified a few key plant and microbial signals regulating these symbioses. Furthermore, genetic studies in legumes have identified the host genetic pathways controlling these symbioses. But, the same depth of information does not exist for the interactions between host plants and PGPB. For instance, our knowledge of the host genes and the pathways involved in these interactions is very poor. However, some transcriptomic studies have investigated the regulation of gene expression in host plants during these interactions in recent years. In this review, we discuss some of the major findings from these studies and discuss what lies ahead. Identifying the genetic pathway(s) regulating these plant-PGPB interactions will be important as we explore ways to improve crop production sustainably.
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Worsley SF, Macey MC, Prudence SMM, Wilkinson B, Murrell JC, Hutchings MI. Investigating the Role of Root Exudates in Recruiting Streptomyces Bacteria to the Arabidopsis thaliana Microbiome. Front Mol Biosci 2021; 8:686110. [PMID: 34222338 PMCID: PMC8241931 DOI: 10.3389/fmolb.2021.686110] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 05/27/2021] [Indexed: 02/01/2023] Open
Abstract
Streptomyces species are saprophytic soil bacteria that produce a diverse array of specialized metabolites, including half of all known antibiotics. They are also rhizobacteria and plant endophytes that can promote plant growth and protect against disease. Several studies have shown that streptomycetes are enriched in the rhizosphere and endosphere of the model plant Arabidopsis thaliana. Here, we set out to test the hypothesis that they are attracted to plant roots by root exudates, and specifically by the plant phytohormone salicylate, which they might use as a nutrient source. We confirmed a previously published report that salicylate over-producing cpr5 plants are colonized more readily by streptomycetes but found that salicylate-deficient sid2-2 and pad4 plants had the same levels of root colonization by Streptomyces bacteria as the wild-type plants. We then tested eight genome sequenced Streptomyces endophyte strains in vitro and found that none were attracted to or could grow on salicylate as a sole carbon source. We next used 13CO2 DNA stable isotope probing to test whether Streptomyces species can feed off a wider range of plant metabolites but found that Streptomyces bacteria were outcompeted by faster growing proteobacteria and did not incorporate photosynthetically fixed carbon into their DNA. We conclude that, given their saprotrophic nature and under conditions of high competition, streptomycetes most likely feed on more complex organic material shed by growing plant roots. Understanding the factors that impact the competitiveness of strains in the plant root microbiome could have consequences for the effective application of biocontrol strains.
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Affiliation(s)
- Sarah F Worsley
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
| | - Michael C Macey
- School of Environmental Sciences, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
| | - Samuel M M Prudence
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, United Kingdom.,Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich, United Kingdom
| | - Barrie Wilkinson
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich, United Kingdom
| | - J Colin Murrell
- School of Environmental Sciences, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
| | - Matthew I Hutchings
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, United Kingdom.,Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich, United Kingdom
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Montiel J, Reid D, Grønbæk TH, Benfeldt CM, James EK, Ott T, Ditengou FA, Nadzieja M, Kelly S, Stougaard J. Distinct signaling routes mediate intercellular and intracellular rhizobial infection in Lotus japonicus. PLANT PHYSIOLOGY 2021; 185:1131-1147. [PMID: 33793909 PMCID: PMC8133683 DOI: 10.1093/plphys/kiaa049] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 11/18/2020] [Indexed: 05/07/2023]
Abstract
Rhizobial infection of legume roots during the development of nitrogen-fixing root nodules can occur intracellularly, through plant-derived infection threads traversing cells, or intercellularly, via bacterial entry between epidermal plant cells. Although it is estimated that around 25% of all legume genera are intercellularly infected, the pathways and mechanisms supporting this process have remained virtually unexplored due to a lack of genetically amenable legumes that exhibit this form of infection. In this study, we report that the model legume Lotus japonicus is infected intercellularly by the IRBG74 strain, recently proposed to belong to the Agrobacterium clade of the Rhizobiaceae. We demonstrate that the resources available for L. japonicus enable insight into the genetic requirements and fine-tuning of the pathway governing intercellular infection in this species. Inoculation of L. japonicus mutants shows that Ethylene-responsive factor required for nodulation 1 (Ern1) and Leu-rich Repeat Receptor-Like Kinase (RinRK1) are dispensable for intercellular infection in contrast to intracellular infection. Other symbiotic genes, including nod factor receptor 5 (NFR5), symbiosis receptor-like kinase (SymRK), Ca2+/calmodulin dependent kinase (CCaMK), exopolysaccharide receptor 3 (Epr3), Cyclops, nodule inception (Nin), nodulation signaling pathway 1 (Nsp1), nodulation signaling pathway 2 (Nsp2), cystathionine-β-synthase (Cbs), and Vapyrin are equally important for both entry modes. Comparative RNAseq analysis of roots inoculated with IRBG74 revealed a distinctive transcriptome response compared with intracellular colonization. In particular, several cytokinin-related genes were differentially regulated. Corroborating this observation, cyp735A and ipt4 cytokinin biosynthesis mutants were significantly affected in their nodulation with IRBG74, whereas lhk1 cytokinin receptor mutants formed no nodules. These results indicate a differential requirement for cytokinin signaling during intercellular rhizobial entry and highlight distinct modalities of inter- and intracellular infection mechanisms in L. japonicus.
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Affiliation(s)
- Jesús Montiel
- Department of Molecular Biology and Genetics, Aarhus University, DK-8000, Aarhus C, Denmark
| | - Dugald Reid
- Department of Molecular Biology and Genetics, Aarhus University, DK-8000, Aarhus C, Denmark
| | - Thomas H Grønbæk
- Department of Molecular Biology and Genetics, Aarhus University, DK-8000, Aarhus C, Denmark
| | - Caroline M Benfeldt
- Department of Molecular Biology and Genetics, Aarhus University, DK-8000, Aarhus C, Denmark
| | - Euan K James
- The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - Thomas Ott
- Cell Biology, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Franck A Ditengou
- Cell Biology, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Marcin Nadzieja
- Department of Molecular Biology and Genetics, Aarhus University, DK-8000, Aarhus C, Denmark
| | - Simon Kelly
- Department of Molecular Biology and Genetics, Aarhus University, DK-8000, Aarhus C, Denmark
| | - Jens Stougaard
- Department of Molecular Biology and Genetics, Aarhus University, DK-8000, Aarhus C, Denmark
- Author for ommunication:
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Concha C, Doerner P. The impact of the rhizobia-legume symbiosis on host root system architecture. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:3902-3921. [PMID: 32337556 PMCID: PMC7316968 DOI: 10.1093/jxb/eraa198] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 04/22/2020] [Indexed: 05/20/2023]
Abstract
Legumes form symbioses with rhizobia to fix N2 in root nodules to supplement their nitrogen (N) requirements. Many studies have shown how symbioses affect the shoot, but far less is understood about how they modify root development and root system architecture (RSA). RSA is the distribution of roots in space and over time. RSA reflects host resource allocation into below-ground organs and patterns of host resource foraging underpinning its resource acquisition capacity. Recent studies have revealed a more comprehensive relationship between hosts and symbionts: the latter can affect host resource acquisition for phosphate and iron, and the symbiont's production of plant growth regulators can enhance host resource flux and abundance. We review the current understanding of the effects of rhizobia-legume symbioses on legume root systems. We focus on resource acquisition and allocation within the host to conceptualize the effect of symbioses on RSA, and highlight opportunities for new directions of research.
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Affiliation(s)
- Cristobal Concha
- Institute for Molecular Plant Science, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Peter Doerner
- Institute for Molecular Plant Science, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
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Garrido-Oter R, Nakano RT, Dombrowski N, Ma KW, McHardy AC, Schulze-Lefert P. Modular Traits of the Rhizobiales Root Microbiota and Their Evolutionary Relationship with Symbiotic Rhizobia. Cell Host Microbe 2019; 24:155-167.e5. [PMID: 30001518 PMCID: PMC6053594 DOI: 10.1016/j.chom.2018.06.006] [Citation(s) in RCA: 153] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 04/16/2018] [Accepted: 06/15/2018] [Indexed: 11/19/2022]
Abstract
Rhizobia are a paraphyletic group of soil-borne bacteria that induce nodule organogenesis in legume roots and fix atmospheric nitrogen for plant growth. In non-leguminous plants, species from the Rhizobiales order define a core lineage of the plant microbiota, suggesting additional functional interactions with plant hosts. In this work, genome analyses of 1,314 Rhizobiales isolates along with amplicon studies of the root microbiota reveal the evolutionary history of nitrogen-fixing symbiosis in this bacterial order. Key symbiosis genes were acquired multiple times, and the most recent common ancestor could colonize roots of a broad host range. In addition, root growth promotion is a characteristic trait of Rhizobiales in Arabidopsis thaliana, whereas interference with plant immunity constitutes a separate, strain-specific phenotype of root commensal Alphaproteobacteria. Additional studies with a tripartite gnotobiotic plant system reveal that these traits operate in a modular fashion and thus might be relevant to microbial homeostasis in healthy roots.
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Affiliation(s)
- Ruben Garrido-Oter
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne 50829, Germany; Cluster of Excellence on Plant Sciences, Dusseldorf 40225, Germany
| | - Ryohei Thomas Nakano
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne 50829, Germany; Cluster of Excellence on Plant Sciences, Dusseldorf 40225, Germany
| | - Nina Dombrowski
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne 50829, Germany; University of Texas Austin, Marine Science Institute, Port Aransas, TX 78373, USA
| | - Ka-Wai Ma
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne 50829, Germany
| | - Alice C McHardy
- Department of Computational Biology of Infection Research, Helmholtz Center for Infection Research, Braunschweig 38124, Germany
| | - Paul Schulze-Lefert
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne 50829, Germany; Cluster of Excellence on Plant Sciences, Dusseldorf 40225, Germany.
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