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Chi Z, Li Y, Zhang J, Hu M, Wu Y, Fan X, Li Z, Miao Q, Li W. Effects of nitrogen application on ammonium assimilation and microenvironment in the rhizosphere of drip-irrigated sunflower under plastic mulch. Front Microbiol 2024; 15:1390331. [PMID: 38841064 PMCID: PMC11150556 DOI: 10.3389/fmicb.2024.1390331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Accepted: 05/07/2024] [Indexed: 06/07/2024] Open
Abstract
This study investigated the effect of nitrogen application on the rhizosphere soil microenvironment of sunflower and clarified the relationship between ammonium assimilation and the microenvironment. In a field experiment high (HN, 190 kg/hm2), medium (MN, 120 kg/hm2) and low nitrogen (CK, 50 kg/hm2) treatments were made to replicate plots of sunflowers using drip irrigation. Metagenomic sequencing was used to analyze the community structure and functional genes involved in the ammonium assimilation pathway in rhizosphere soil. The findings indicated that glnA and gltB played a crucial role in the ammonium assimilation pathway in sunflower rhizosphere soil, with Actinobacteria and Proteobacteria being the primary contributors. Compared with CK treatment, the relative abundance of Actinobacteria increased by 15.57% under MN treatment, while the relative abundance decreased at flowering and maturation stages. Conversely, the relative abundance of Proteobacteria was 28.57 and 61.26% higher in the MN treatment during anthesis and maturation period, respectively, compared with the CK. Furthermore, during the bud stage and anthesis, the abundance of Actinobacteria, Proteobacteria, and their dominant species were influenced mainly by rhizosphere soil EC, ammonium nitrogen (NH 4 + -N), and nitrate nitrogen (NO 3 - -N), whereas, at maturity, soil pH and NO 3 - -N played a more significant role in shaping the community of ammonium-assimilating microorganisms. The MN treatment increased the root length density, surface area density, and root volume density of sunflower at the bud, flowering, and maturity stages compared to the CK. Moreover, root exudates such as oxalate and malate were positively correlated with the dominant species of Actinobacteria and Proteobacteria during anthesis and the maturation period. Under drip irrigation, applying 120 kg/hm2 of nitrogen to sunflowers effectively promoted the community structure of ammonium-assimilating microorganisms in rhizosphere soil and had a positive influence on the rhizosphere soil microenvironment and sunflower root growth.
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Affiliation(s)
- Zhaonan Chi
- College of Water Conservancy and Civil Engineering, Inner Mongolia Agricultural University, Hohhot, China
| | - Yuxin Li
- Inner Mongolia Key Lab of Molecular Biology, Inner Mongolia Medical University, Hohhot, China
| | - Jiapeng Zhang
- College of Water Conservancy and Civil Engineering, Inner Mongolia Agricultural University, Hohhot, China
| | - Min Hu
- Vocational and Technical College of Inner Mongolia Agricultural University, Baotou, China
| | - Yixuan Wu
- College of Water Conservancy and Civil Engineering, Inner Mongolia Agricultural University, Hohhot, China
| | - Xueqin Fan
- College of Water Conservancy and Civil Engineering, Inner Mongolia Agricultural University, Hohhot, China
| | - Zhen Li
- College of Water Conservancy and Civil Engineering, Inner Mongolia Agricultural University, Hohhot, China
| | - Qingfeng Miao
- College of Water Conservancy and Civil Engineering, Inner Mongolia Agricultural University, Hohhot, China
| | - Weiping Li
- College of Water Conservancy and Civil Engineering, Inner Mongolia Agricultural University, Hohhot, China
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Han F, Li H, Lyu E, Zhang Q, Gai H, Xu Y, Bai X, He X, Khan AQ, Li X, Xie F, Li F, Fang X, Wei M. Soybean-mediated suppression of BjaI/BjaR 1 quorum sensing in Bradyrhizobium diazoefficiens impacts symbiotic nitrogen fixation. Appl Environ Microbiol 2024; 90:e0137423. [PMID: 38251894 PMCID: PMC10880635 DOI: 10.1128/aem.01374-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 11/23/2023] [Indexed: 01/23/2024] Open
Abstract
The acyl-homoserine lactones (AHLs)-mediated LuxI/LuxR quorum sensing (QS) system orchestrates diverse bacterial behaviors in response to changes in population density. The role of the BjaI/BjaR1 QS system in Bradyrhizobium diazoefficiens USDA 110, which shares homology with LuxI/LuxR, remains elusive during symbiotic interaction with soybean. Here this genetic system in wild-type (WT) bacteria residing inside nodules exhibited significantly reduced activity compared to free-living cells, potentially attributed to soybean-mediated suppression. The deletion mutant strain ΔbjaR1 showed significantly enhanced nodulation induction and nitrogen fixation ability. Nevertheless, its ultimate symbiotic outcome (plant dry weight) in soybeans was compromised. Furthermore, comparative analysis of the transcriptome, proteome, and promoter activity revealed that the inactivation of BjaR1 systematically activated and inhibited genomic modules associated with nodulation and nitrogen metabolism. The former appeared to be linked to a significant decrease in the expression of NodD2, a key cell-density-dependent repressor of nodulation genes, while the latter conferred bacterial growth and nitrogen fixation insensitivity to environmental nitrogen. In addition, BjaR1 exerted a positive influence on the transcription of multiple genes involved in a so-called central intermediate metabolism within the nodule. In conclusion, our findings highlight the crucial role of the BjaI/BjaR1 QS circuit in positively regulating bacterial nitrogen metabolism and emphasize the significance of the soybean-mediated suppression of this genetic system for promoting efficient symbiotic nitrogen fixation by B. diazoefficiens.IMPORTANCEThe present study demonstrates, for the first time, that the BjaI/BjaR1 QS system of Bradyrhizobium diazoefficiens has a significant impact on its nodulation and nitrogen fixation capability in soybean by positively regulating NodD2 expression and bacterial nitrogen metabolism. Moreover, it provides novel insights into the importance of suppressing the activity of this QS circuit by the soybean host plant in establishing an efficient mutual relationship between the two symbiotic partners. This research expands our understanding of legumes' role in modulating symbiotic nitrogen fixation through rhizobial QS-mediated metabolic functioning, thereby deepening our comprehension of symbiotic coevolution theory. In addition, these findings may hold great promise for developing quorum quenching technology in agriculture.
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Affiliation(s)
- Fang Han
- State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, College of Ecology, Lanzhou University, Lanzhou, China
| | - Huiquan Li
- State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, College of Ecology, Lanzhou University, Lanzhou, China
| | - Ermeng Lyu
- State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, College of Ecology, Lanzhou University, Lanzhou, China
| | - Qianqian Zhang
- State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, College of Ecology, Lanzhou University, Lanzhou, China
| | - Haoyu Gai
- State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, College of Ecology, Lanzhou University, Lanzhou, China
| | - Yunfang Xu
- State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, College of Ecology, Lanzhou University, Lanzhou, China
| | - Xuemei Bai
- State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, College of Ecology, Lanzhou University, Lanzhou, China
| | - Xueqian He
- State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, College of Ecology, Lanzhou University, Lanzhou, China
| | - Abdul Qadir Khan
- State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, College of Ecology, Lanzhou University, Lanzhou, China
| | - Xiaolin Li
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- University of the Chinese Academy of Sciences, Beijing, China
| | - Fang Xie
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Fengmin Li
- State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, College of Ecology, Lanzhou University, Lanzhou, China
| | - Xiangwen Fang
- State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, College of Ecology, Lanzhou University, Lanzhou, China
| | - Min Wei
- State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, College of Ecology, Lanzhou University, Lanzhou, China
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Nelson C, Dadi P, Shah DD, Garcia-Pichel F. Spatial organization of a soil cyanobacterium and its cyanosphere through GABA/Glu signaling to optimize mutualistic nitrogen fixation. THE ISME JOURNAL 2024; 18:wrad029. [PMID: 38366166 PMCID: PMC10881301 DOI: 10.1093/ismejo/wrad029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 12/02/2023] [Accepted: 12/08/2023] [Indexed: 02/18/2024]
Abstract
Soil biocrusts are characterized by the spatial self-organization of resident microbial populations at small scales. The cyanobacterium Microcoleus vaginatus, a prominent primary producer and pioneer biocrust former, relies on a mutualistic carbon (C) for nitrogen (N) exchange with its heterotrophic cyanosphere microbiome, a mutualism that may be optimized through the ability of the cyanobacterium to aggregate into bundles of trichomes. Testing both environmental populations and representative isolates, we show that the proximity of mutualistic diazotroph populations results in M. vaginatus bundle formation orchestrated through chemophobic and chemokinetic responses to gamma-aminobutyric acid (GABA) /glutamate (Glu) signals. The signaling system is characterized by: a high GABA sensitivity (nM range) and low Glu sensitivity (μM to mM), the fact that GABA and Glu are produced by the cyanobacterium as an autoinduction response to N deficiency, and by the presence of interspecific signaling by heterotrophs in response to C limitation. Further, it crucially switches from a positive to a negative feedback loop with increasing GABA concentration, thus setting maximal bundle sizes. The unprecedented use of GABA/Glu as an intra- and interspecific signal in the spatial organization of microbiomes highlights the pair as truly universal infochemicals.
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Affiliation(s)
- Corey Nelson
- Center for Fundamental and Applied Microbiomics, Biodesign Institute, Arizona State University, Tempe, AZ 85287, United States
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, United States
- Instituto Multidisciplinar Para Estudios del Medio “Ramon Margalef”, Universidad de Alicante, San Vicente del Raspeig 03690, Spain
| | - Pavani Dadi
- Center for Fundamental and Applied Microbiomics, Biodesign Institute, Arizona State University, Tempe, AZ 85287, United States
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, United States
| | - Dhara D Shah
- Center for Fundamental and Applied Microbiomics, Biodesign Institute, Arizona State University, Tempe, AZ 85287, United States
- School of Mathematical and Natural Sciences, Arizona State University, Glendale, AZ 85306, United States
| | - Ferran Garcia-Pichel
- Center for Fundamental and Applied Microbiomics, Biodesign Institute, Arizona State University, Tempe, AZ 85287, United States
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, United States
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Chen E, Yang C, Tao W, Li S. Polysaccharides Produced by Plant Growth-Promoting Rhizobacteria Strain Burkholderia sp. BK01 Enhance Salt Stress Tolerance to Arabidopsis thaliana. Polymers (Basel) 2024; 16:145. [PMID: 38201810 PMCID: PMC10780357 DOI: 10.3390/polym16010145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 12/26/2023] [Accepted: 12/29/2023] [Indexed: 01/12/2024] Open
Abstract
Salt stress is one of the most serious abiotic stresses leading to reduced agricultural productivity. Polysaccharides from seaweed have been used as biostimulants to promote crop growth and improve plant resistance to abiotic stress. In this study, PGPR strain Burkholderia sp. BK01 was isolated from the rhizosphere of wheat, and it was characterized for phosphorus (Pi) dissolution, indole-3-acetic acid (IAA) production, ammonia (NH3) and exopolysaccharides (EPS). In particular, strain BK01 can efficiently produce extracellular polysaccharide with a yield of 12.86 g/L, using sorbitol as carbon source. BK01 EPS was identified as an heteropolysaccharide with Mw 3.559 × 106 Da, composed of (D)-galactose (75.3%), (D)-glucose (5.5%), (L)-rhamnose (5.5%), (D)-galactouronic acid (4.9%) and (D)-glucuronic acid (8.8%). The present work aims to highlight the effect of the BK01 EPS on growth and biochemical changes in Arabidopsis thaliana under salt stress (100 mM). The purified BK01 EPS at a concentration of 100 mg/L efficiently promoted the growth of plants in pot assays, improved the chlorophyll content, enhanced the activities of SOD, POD and CAT, and decreased the content of MDA. This results suggested that the polysaccharides produced by PGPR strain Burkholderia sp. BK01 can be used as biostimulants to promote plant growth and improve plant resistance to salt stress.
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Affiliation(s)
- Enni Chen
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, China; (E.C.); (C.Y.)
| | - Changsheng Yang
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, China; (E.C.); (C.Y.)
| | - Weiyi Tao
- College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China;
| | - Shuang Li
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, China; (E.C.); (C.Y.)
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García-Tomsig NI, Guedes-García SK, Jiménez-Zurdo JI. A Workflow for the Functional Characterization of Noncoding RNAs in Legume Symbiotic Bacteria. Methods Mol Biol 2024; 2751:179-203. [PMID: 38265717 DOI: 10.1007/978-1-0716-3617-6_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2024]
Abstract
Computational comparative genomics and, later, high-throughput transcriptome profiling (RNAseq) have uncovered a plethora of small noncoding RNA species (sRNAs) with potential regulatory roles in bacteria. A large fraction of sRNAs are differentially regulated in response to different biotic and abiotic stimuli and have the ability to fine-tune posttranscriptional reprogramming of gene expression through protein-assisted antisense interactions with trans-encoded target mRNAs. However, this level of gene regulation is still understudied in most non-model bacteria. Here, we compile experimental methods to detect expression, determine 5'/3'-ends, assess transcriptional regulation, generate mutants, and validate candidate target mRNAs of trans-acting sRNAs (trans-sRNAs) identified in the nitrogen-fixing α-rhizobium Sinorhizobium meliloti. The workflow, molecular tools, and methods are suited to investigate the function of newly identified base-pairing trans-sRNAs in phylogenetically related α-rhizobia.
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Affiliation(s)
- Natalia I García-Tomsig
- Structure, Dynamics and Function of Rhizobacterial Genomes (RhizoRNA Lab), Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Granada, Spain
| | - Sabina K Guedes-García
- Structure, Dynamics and Function of Rhizobacterial Genomes (RhizoRNA Lab), Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Granada, Spain
| | - José I Jiménez-Zurdo
- Structure, Dynamics and Function of Rhizobacterial Genomes (RhizoRNA Lab), Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Granada, Spain.
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6
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García-Tomsig NI, García-Rodriguez FM, Guedes-García SK, Millán V, Becker A, Robledo M, Jiménez-Zurdo JI. A double-negative feedback loop between NtrBC and a small RNA rewires nitrogen metabolism in legume symbionts. mBio 2023; 14:e0200323. [PMID: 37850753 PMCID: PMC10746234 DOI: 10.1128/mbio.02003-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 09/05/2023] [Indexed: 10/19/2023] Open
Abstract
IMPORTANCE Root nodule endosymbioses between diazotrophic rhizobia and legumes provide the largest input of combined N to the biosphere, thus representing an alternative to harmful chemical fertilizers for sustainable crop production. Rhizobia have evolved intricate strategies to coordinate N assimilation for their own benefit with N2 fixation to sustain plant growth. The rhizobial N status is transduced by the NtrBC two-component system, the seemingly ubiquitous form of N signal transduction in Proteobacteria. Here, we show that the regulatory sRNA NfeR1 (nodule formation efficiency RNA) of the alfalfa symbiont Sinorhizobium meliloti is transcribed from a complex promoter repressed by NtrC in a N-dependent manner and feedback silences ntrBC by complementary base-pairing. These findings unveil a more prominent role of NtrC as a transcriptional repressor than hitherto anticipated and a novel RNA-based mechanism for NtrBC regulation. The NtrBC-NfeR1 double-negative feedback loop accurately rewires symbiotic S. meliloti N metabolism and is likely conserved in α-rhizobia.
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Affiliation(s)
- Natalia I. García-Tomsig
- Structure, Dynamics and Function of Rhizobacterial Genomes (RhizoRNA Lab), Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Granada, Spain
| | - Fernando M. García-Rodriguez
- Structure, Dynamics and Function of Rhizobacterial Genomes (RhizoRNA Lab), Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Granada, Spain
| | - Sabina K. Guedes-García
- Structure, Dynamics and Function of Rhizobacterial Genomes (RhizoRNA Lab), Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Granada, Spain
| | - Vicenta Millán
- Structure, Dynamics and Function of Rhizobacterial Genomes (RhizoRNA Lab), Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Granada, Spain
| | - Anke Becker
- Center for Synthetic Microbiology (SYNMIKRO), Philipps-Universität Marburg, Marburg, Germany
| | - Marta Robledo
- Structure, Dynamics and Function of Rhizobacterial Genomes (RhizoRNA Lab), Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Granada, Spain
| | - José I. Jiménez-Zurdo
- Structure, Dynamics and Function of Rhizobacterial Genomes (RhizoRNA Lab), Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Granada, Spain
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Tang Y, Qin D, Tian Z, Chen W, Ma Y, Wang J, Yang J, Yan D, Dixon R, Wang YP. Diurnal switches in diazotrophic lifestyle increase nitrogen contribution to cereals. Nat Commun 2023; 14:7516. [PMID: 37980355 PMCID: PMC10657418 DOI: 10.1038/s41467-023-43370-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 11/07/2023] [Indexed: 11/20/2023] Open
Abstract
Uncoupling of biological nitrogen fixation from ammonia assimilation is a prerequisite step for engineering ammonia excretion and improvement of plant-associative nitrogen fixation. In this study, we have identified an amino acid substitution in glutamine synthetase, which provides temperature sensitive biosynthesis of glutamine, the intracellular metabolic signal of the nitrogen status. As a consequence, negative feedback regulation of genes and enzymes subject to nitrogen regulation, including nitrogenase is thermally controlled, enabling ammonia excretion in engineered Escherichia coli and the plant-associated diazotroph Klebsiella oxytoca at 23 °C, but not at 30 °C. We demonstrate that this temperature profile can be exploited to provide diurnal oscillation of ammonia excretion when variant bacteria are used to inoculate cereal crops. We provide evidence that diurnal temperature variation improves nitrogen donation to the plant because the inoculant bacteria have the ability to recover and proliferate at higher temperatures during the daytime.
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Affiliation(s)
- Yuqian Tang
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences & School of Advanced Agricultural Sciences, Peking University, Beijing, 100871, China
| | - Debin Qin
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences & School of Advanced Agricultural Sciences, Peking University, Beijing, 100871, China
| | - Zhexian Tian
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences & School of Advanced Agricultural Sciences, Peking University, Beijing, 100871, China
| | - Wenxi Chen
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences & School of Advanced Agricultural Sciences, Peking University, Beijing, 100871, China
| | - Yuanxi Ma
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences & School of Advanced Agricultural Sciences, Peking University, Beijing, 100871, China
| | - Jilong Wang
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences & School of Advanced Agricultural Sciences, Peking University, Beijing, 100871, China
| | - Jianguo Yang
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences & School of Advanced Agricultural Sciences, Peking University, Beijing, 100871, China
| | - Dalai Yan
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Ray Dixon
- Department of Molecular Microbiology, John Innes Centre, Norwich, NR4 7UH, UK.
| | - Yi-Ping Wang
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences & School of Advanced Agricultural Sciences, Peking University, Beijing, 100871, China.
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Shahid M, Khan MS, Singh UB. Pesticide-tolerant microbial consortia: Potential candidates for remediation/clean-up of pesticide-contaminated agricultural soil. ENVIRONMENTAL RESEARCH 2023; 236:116724. [PMID: 37500042 DOI: 10.1016/j.envres.2023.116724] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2023] [Revised: 07/16/2023] [Accepted: 07/21/2023] [Indexed: 07/29/2023]
Abstract
Reclamation of pesticide-polluted lands has long been a difficult endeavour. The use of synthetic pesticides could not be restricted due to rising agricultural demand. Pesticide toxicity has become a pressing agronomic problem due to its adverse impact on agroecosystems, agricultural output, and consequently food security and safety. Among different techniques used for the reclamation of pesticide-polluted sites, microbial bioremediation is an eco-friendly approach, which focuses on the application of resilient plant growth promoting rhizobacteria (PGPR) that may transform or degrade chemical pesticides to innocuous forms. Such pesticide-resilient PGPR has demonstrated favourable effects on soil-plant systems, even in pesticide-contaminated environments, by degrading pesticides, providing macro-and micronutrients, and secreting active but variable secondary metabolites like-phytohormones, siderophores, ACC deaminase, etc. This review critically aims to advance mechanistic understanding related to the reduction of phytotoxicity of pesticides via the use of microbe-mediated remediation techniques leading to crop optimization in pesticide-stressed soils. The literature surveyed and data presented herein are extremely useful, offering agronomists-and crop protectionists microbes-assisted remedial strategies for affordably enhancing crop productivity in pesticide-stressed soils.
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Affiliation(s)
- Mohammad Shahid
- Plant-Microbe Interaction and Rhizosphere Biology Lab, ICAR-National Bureau of Agriculturally Important Microorganisms (NBAIM), Kushmaur, Mau Nath Bhanjan, 275103, UP, India; Department of Agricultural Microbiology, Faculty of Agriculture Science, Aligarh Muslim University (A.M.U.), Aligarh, 202001, UP, India.
| | - Mohammad Saghir Khan
- Department of Agricultural Microbiology, Faculty of Agriculture Science, Aligarh Muslim University (A.M.U.), Aligarh, 202001, UP, India
| | - Udai B Singh
- Plant-Microbe Interaction and Rhizosphere Biology Lab, ICAR-National Bureau of Agriculturally Important Microorganisms (NBAIM), Kushmaur, Mau Nath Bhanjan, 275103, UP, India
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Zuo H, Shen H, Dong S, Wu S, He F, Zhang R, Wang Z, Shi H, Hao X, Tan Y, Ma C, Li S, Liu Y, Zhang F, Xiao J. Potential short-term effects of earthquake on the plant-soil interface in alpine grassland of the Qinghai-Tibetan Plateau. FRONTIERS IN PLANT SCIENCE 2023; 14:1240719. [PMID: 37915511 PMCID: PMC10616788 DOI: 10.3389/fpls.2023.1240719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Accepted: 09/26/2023] [Indexed: 11/03/2023]
Abstract
Earthquakes are environmental disturbances affecting ecosystem functioning, health, and biodiversity, but their potential impacts on plant-soil interface are still poorly understood. In this study, grassland habitats in areas near and away from the seismo-fault in Madou, a region typical of alpine conditions on the Qinghai-Tibetan Plateau, were randomly selected. The impacts of earthquake on soil properties and plant nutrient content in the short term were emphasized, and their potential relationships with community diversity and productivity were examined. According to the findings of the study, the Maduo earthquake led to a decrease in soil nutrient content in alpine grassland ecosystems, especially soil TC, TN, TP, TCa, AP, AK, NH4 +-N, and SOC, and inhibited the absorption of N, Ca, and Mg nutrients by plants. In addition, the diversity and productivity of communities were affected by both direct and indirect earthquake pathways. The negative impacts of seismic fracture on soil structure had the most significant direct impact on plant community diversity. Earthquakes also indirectly reduced community productivity by reducing the soil N content and inhibiting the absorption of plant nutrients. Our findings suggested that earthquakes could potentially decrease the stability of the alpine grassland ecosystem on the QTP by affecting nutrient availability at the plant-soil interface.
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Affiliation(s)
- Hui Zuo
- School of Grassland Science, Beijing Forestry University, Beijing, China
| | - Hao Shen
- School of Grassland Science, Beijing Forestry University, Beijing, China
| | - Shikui Dong
- School of Grassland Science, Beijing Forestry University, Beijing, China
- Department of Natural Resources, Cornell University, Ithaca, NY, United States
| | - Shengnan Wu
- School of Grassland Science, Beijing Forestry University, Beijing, China
| | - Fengcai He
- School of Grassland Science, Beijing Forestry University, Beijing, China
| | - Ran Zhang
- School of Grassland Science, Beijing Forestry University, Beijing, China
| | - Ziying Wang
- School of Grassland Science, Beijing Forestry University, Beijing, China
| | - Hang Shi
- School of Grassland Science, Beijing Forestry University, Beijing, China
| | - Xinghai Hao
- School of Grassland Science, Beijing Forestry University, Beijing, China
| | - Youquan Tan
- School of Grassland Science, Beijing Forestry University, Beijing, China
| | - Chunhui Ma
- School of Grassland Science, Beijing Forestry University, Beijing, China
| | - Shengmei Li
- School of Grassland Science, Beijing Forestry University, Beijing, China
| | - Yongqi Liu
- School of Grassland Science, Beijing Forestry University, Beijing, China
| | - Feng Zhang
- School of Grassland Science, Beijing Forestry University, Beijing, China
| | - Jiannan Xiao
- School of Environment, State Key Joint Laboratory of Environmental Simulation and Pollution Control, Beijing Normal University, Beijing, China
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10
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Li X, Li Z. What determines symbiotic nitrogen fixation efficiency in rhizobium: recent insights into Rhizobium leguminosarum. Arch Microbiol 2023; 205:300. [PMID: 37542687 DOI: 10.1007/s00203-023-03640-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 07/21/2023] [Accepted: 07/24/2023] [Indexed: 08/07/2023]
Abstract
Symbiotic nitrogen fixation (SNF) by rhizobium, a Gram-negative soil bacterium, is an essential component in the nitrogen cycle and is a sustainable green way to maintain soil fertility without chemical energy consumption. SNF, which results from the processes of nodulation, rhizobial infection, bacteroid differentiation and nitrogen-fixing reaction, requires the expression of various genes from both symbionts with adaptation to the changing environment. To achieve successful nitrogen fixation, rhizobia and their hosts cooperate closely for precise regulation of symbiotic genes, metabolic processes and internal environment homeostasis. Many researches have progressed to reveal the ample information about regulatory aspects of SNF during recent decades, but the major bottlenecks regarding improvement of nitrogen-fixing efficiency has proven to be complex. In this mini-review, we summarize recent advances that have contributed to understanding the rhizobial regulatory aspects that determine SNF efficiency, focusing on the coordinated regulatory mechanism of symbiotic genes, oxygen, carbon metabolism, amino acid metabolism, combined nitrogen, non-coding RNAs and internal environment homeostasis. Unraveling regulatory determinants of SNF in the nitrogen-fixing protagonist rhizobium is expected to promote an improvement of nitrogen-fixing efficiency in crop production.
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Affiliation(s)
- Xiaofang Li
- Institute of Biopharmaceuticals, Taizhou University, 1139 Shifu Avenue, Taizhou, 318000, China.
- School of Pharmaceutical Sciences, Taizhou University, 1139 Shifu Avenue, Taizhou, 318000, China.
| | - Zhangqun Li
- School of Pharmaceutical Sciences, Taizhou University, 1139 Shifu Avenue, Taizhou, 318000, China
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11
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Lepetit M, Brouquisse R. Control of the rhizobium-legume symbiosis by the plant nitrogen demand is tightly integrated at the whole plant level and requires inter-organ systemic signaling. FRONTIERS IN PLANT SCIENCE 2023; 14:1114840. [PMID: 36968361 PMCID: PMC10033964 DOI: 10.3389/fpls.2023.1114840] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 02/16/2023] [Indexed: 06/18/2023]
Abstract
Symbiotic nodules formed on legume roots with rhizobia fix atmospheric N2. Bacteria reduce N2 to NH4 + that is assimilated into amino acids by the plant. In return, the plant provides photosynthates to fuel the symbiotic nitrogen fixation. Symbiosis is tightly adjusted to the whole plant nutritional demand and to the plant photosynthetic capacities, but regulatory circuits behind this control remain poorly understood. The use of split-root systems combined with biochemical, physiological, metabolomic, transcriptomic, and genetic approaches revealed that multiple pathways are acting in parallel. Systemic signaling mechanisms of the plant N demand are required for the control of nodule organogenesis, mature nodule functioning, and nodule senescence. N-satiety/N-deficit systemic signaling correlates with rapid variations of the nodules' sugar levels, tuning symbiosis by C resources allocation. These mechanisms are responsible for the adjustment of plant symbiotic capacities to the mineral N resources. On the one hand, if mineral N can satisfy the plant N demand, nodule formation is inhibited, and nodule senescence is activated. On the other hand, local conditions (abiotic stresses) may impair symbiotic activity resulting in plant N limitation. In these conditions, systemic signaling may compensate the N deficit by stimulating symbiotic root N foraging. In the past decade, several molecular components of the systemic signaling pathways controlling nodule formation have been identified, but a major challenge remains, that is, to understand their specificity as compared to the mechanisms of non-symbiotic plants that control root development and how they contribute to the whole plant phenotypes. Less is known about the control of mature nodule development and functioning by N and C nutritional status of the plant, but a hypothetical model involving the sucrose allocation to the nodule as a systemic signaling process, the oxidative pentose phosphate pathway, and the redox status as potential effectors of this signaling is emerging. This work highlights the importance of organism integration in plant biology.
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Jhu MY, Oldroyd GED. Dancing to a different tune, can we switch from chemical to biological nitrogen fixation for sustainable food security? PLoS Biol 2023; 21:e3001982. [PMID: 36917569 PMCID: PMC10013914 DOI: 10.1371/journal.pbio.3001982] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023] Open
Abstract
Our current food production systems are unsustainable, driven in part through the application of chemically fixed nitrogen. We need alternatives to empower farmers to maximise their productivity sustainably. Therefore, we explore the potential for transferring the root nodule symbiosis from legumes to other crops. Studies over the last decades have shown that preexisting developmental and signal transduction processes were recruited during the evolution of legume nodulation. This allows us to utilise these preexisting processes to engineer nitrogen fixation in target crops. Here, we highlight our understanding of legume nodulation and future research directions that might help to overcome the barrier of achieving self-fertilising crops.
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Affiliation(s)
- Min-Yao Jhu
- Crop Science Centre, Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Giles E. D. Oldroyd
- Crop Science Centre, Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
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13
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Ottinger SL, Miniat CF, Wurzburger N. Nitrogen and light regulate symbiotic nitrogen fixation by a temperate forest tree. Oecologia 2023; 201:565-574. [PMID: 36637524 DOI: 10.1007/s00442-023-05313-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 01/03/2023] [Indexed: 01/14/2023]
Abstract
Symbiotic nitrogen fixation (SNF) is a critical mechanism of ecosystem recovery, and in forests of the eastern United States, the most common tree species that supports SNF is black locust (Robinia pseudoacacia L.). Despite its prevalence, black locust's fixation strategy-whether it maintains fixation at a constant rate (obligate fixation) or reduces its fixation rate (facultative fixation)-is unknown. Here, we examined how nitrogen and light control SNF by black locust, by growing seedlings under two nitrogen levels and across four levels of light. Seedlings were harvested after 12 weeks to determine biomass changes, nodule activity, and photosynthetic rates. Black locust seedlings increased biomass growth with increasing light, but only in the absence of nitrogen addition, while seedling root:shoot (biomass) modestly declined with increasing light regardless of nitrogen level. We found that black locust behaved like a facultative fixer, and regulated fixation by excising or maintaining nodules, and by controlling nodule biomass and activity. Specifically, nitrogen addition reduced seedling investment in nodule biomass (g g-1) by 63%, and reduced seedling allocation to nitrogen fixation (µmol C2H4 g-1 h-1) by 66%. In contrast, light affected nitrogen fixation through two indirect pathways. First, light increased plant growth, and hence nitrogen demands, which caused an increase in nitrogen fixation proportional to biomass. Second, light increasd photosynthetic activity, which was positively associated with nodule activity, but only in the absence of nitrogen addition. Our findings for how black locust regulates SNF can improve predictions of ecosystem SNF under the changing environmental conditions.
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Affiliation(s)
| | - Chelcy Ford Miniat
- USDA Forest Service, Rocky Mountain Research Station, Albuquerque, NM, USA
| | - Nina Wurzburger
- Odum School of Ecology, University of Georgia, Athens, GA, USA.
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14
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Valmas MI, Sexauer M, Markmann K, Tsikou D. Plants Recruit Peptides and Micro RNAs to Regulate Nutrient Acquisition from Soil and Symbiosis. PLANTS (BASEL, SWITZERLAND) 2023; 12:187. [PMID: 36616316 PMCID: PMC9824779 DOI: 10.3390/plants12010187] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 12/24/2022] [Accepted: 12/27/2022] [Indexed: 06/17/2023]
Abstract
Plants engage in symbiotic relationships with soil microorganisms to overcome nutrient limitations in their environment. Among the best studied endosymbiotic interactions in plants are those with arbuscular mycorrhizal (AM) fungi and N-fixing bacteria called rhizobia. The mechanisms regulating plant nutrient homeostasis and acquisition involve small mobile molecules such as peptides and micro RNAs (miRNAs). A large number of CLE (CLAVATA3/EMBRYO SURROUNDING REGION-RELATED) and CEP (C-TERMINALLY ENCODED PEPTIDE) peptide hormones as well as certain miRNAs have been reported to differentially respond to the availability of essential nutrients such as nitrogen (N) and phosphorus (P). Interestingly, a partially overlapping pool of these molecules is involved in plant responses to root colonization by rhizobia and AM fungi, as well as mineral nutrition. The crosstalk between root endosymbiosis and nutrient availability has been subject of intense investigations, and new insights in locally or systemically mobile molecules in nutrient- as well as symbiosis-related signaling continue to arise. Focusing on the key roles of peptides and miRNAs, we review the mechanisms that shape plant responses to nutrient limitation and regulate the establishment of symbiotic associations with beneficial soil microorganisms.
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Affiliation(s)
- Marios I. Valmas
- Department of Biochemistry and Biotechnology, University of Thessaly, Biopolis, 41500 Larissa, Greece
| | - Moritz Sexauer
- Julius-von-Sachs-Institute for Biosciences, Würzburg University, Julius-von-Sachs-Platz 3, 97082 Würzburg, Germany
| | - Katharina Markmann
- Julius-von-Sachs-Institute for Biosciences, Würzburg University, Julius-von-Sachs-Platz 3, 97082 Würzburg, Germany
| | - Daniela Tsikou
- Department of Biochemistry and Biotechnology, University of Thessaly, Biopolis, 41500 Larissa, Greece
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Cuartero J, Pascual JA, Vivo JM, Özbolat O, Sánchez-Navarro V, Weiss J, Zornoza R, Martínez-Mena M, García E, Ros M. Melon/cowpea intercropping pattern influenced the N and C soil cycling and the abundance of soil rare bacterial taxa. Front Microbiol 2022; 13:1004593. [PMID: 36419434 PMCID: PMC9676475 DOI: 10.3389/fmicb.2022.1004593] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Accepted: 10/17/2022] [Indexed: 11/09/2022] Open
Abstract
The high use of pesticides, herbicides, and unsustainable farming practices resulted in losses of soil quality. Sustainable farming practices such as intercropping could be a good alternative to traditional monocrop, especially using legumes such as cowpea (Vigna unguiculata L. Walp). In this study, different melon and cowpea intercropping patterns (melon mixed with cowpea in the same row (MC1); alternating one melon row and one cowpea row (MC2); alternating two melon rows and one cowpea row (MC3)) were assayed to study the intercropping effect on soil bacterial community through 16S rRNA region in a 3-year experiment. The results indicated that intercropping showed high content of total organic carbon, total nitrogen and ammonium, melon yield, and bacterial diversity as well as higher levels of beneficial soil microorganisms such a Pseudomonas, Aeromicrobium, Niastella, or Sphingomonas which can promote plant growth and plant defense against pathogens. Furthermore, intercropping showed a higher rare taxa diversity in two (MC1 and MC2) out of the three intercropping systems. In addition, N-cycling genes such as nirB, nosZ, and amoA were more abundant in MC1 and MC2 whereas the narG predicted gene was far more abundant in the intercropping systems than in the monocrop at the end of the 3-year experiment. This research fills a gap in knowledge about the importance of soil bacteria in an intercropping melon/cowpea pattern, showing the benefits to yield and soil quality with a decrease in N fertilization.
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Affiliation(s)
- Jessica Cuartero
- Centre of Edaphology and Applied Biology of the Segura (CSIC), University Campus of Espinardo, Murcia, Spain
| | - Jose Antonio Pascual
- Centre of Edaphology and Applied Biology of the Segura (CSIC), University Campus of Espinardo, Murcia, Spain
| | - Juana-María Vivo
- Department of Statistics and Operations Research, CMN & IMIB-Arrixaca, University of Murcia, Murcia, Spain
| | - Onurcan Özbolat
- Institute of Plant Biotechnology, Plaza del Hospital s/n, Technical University of Cartagena, Cartagena, Spain
| | - Virginia Sánchez-Navarro
- Institute of Plant Biotechnology, Plaza del Hospital s/n, Technical University of Cartagena, Cartagena, Spain
| | - Julia Weiss
- Institute of Plant Biotechnology, Plaza del Hospital s/n, Technical University of Cartagena, Cartagena, Spain
| | - Raúl Zornoza
- Institute of Plant Biotechnology, Plaza del Hospital s/n, Technical University of Cartagena, Cartagena, Spain
- Department of Agricultural Science, Polytechnic University of Cartagena, Cartagena, Spain
| | - María Martínez-Mena
- Centre of Edaphology and Applied Biology of the Segura (CSIC), University Campus of Espinardo, Murcia, Spain
| | - Eloisa García
- Centre of Edaphology and Applied Biology of the Segura (CSIC), University Campus of Espinardo, Murcia, Spain
| | - Margarita Ros
- Centre of Edaphology and Applied Biology of the Segura (CSIC), University Campus of Espinardo, Murcia, Spain
- *Correspondence: Margarita Ros
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Ruiz B, Sauviac L, Brouquisse R, Bruand C, Meilhoc E. Role of Nitric Oxide of Bacterial Origin in the Medicago truncatula-Sinorhizobium meliloti Symbiosis. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2022; 35:887-892. [PMID: 35762680 DOI: 10.1094/mpmi-05-22-0118-sc] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Nitric oxide (NO) is a small ubiquitous gaseous molecule that has been found in many host-pathogen interactions. NO has been shown to be part of the defense arsenal of animal cells and more recently of plant cells. To fight this molecular weapon, pathogens have evolved responses consisting of adaptation to NO or degradation of this toxic molecule. More recently, it was shown that NO could also be produced by the pathogen and contributes likewise to the success of the host cell infection. NO is also present during symbiotic interactions. Despite growing knowledge about the role of NO during friendly interactions, data on the specificity of action of NO produced by each partner are scarce, partly due to the multiplicity of NO production systems. In the nitrogen-fixing symbiosis between the soil bacterium Sinorhizobium meliloti and the model legume Medicago truncatula, NO has been detected at all steps of the interaction, where it displays various roles. Both partners contribute to NO production inside the legume root nodules where nitrogen fixation occurs. The study focuses on the role of bacterial NO in this interaction. We used a genetic approach to identify bacterial NO sources in the symbiotic context and to test the phenotype in planta of bacterial mutants affected in NO production. Our results show that only denitrification is a source of bacterial NO in Medicago nodules, giving insight into the role of bacteria-derived NO at different steps of the symbiotic interaction. [Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Bryan Ruiz
- Laboratoire des Interactions Plantes-Microbes-Environnement (LIPME), Université de Toulouse, INRAE, CNRS, INSA, Castanet-Tolosan, France
| | - Laurent Sauviac
- Laboratoire des Interactions Plantes-Microbes-Environnement (LIPME), Université de Toulouse, INRAE, CNRS, INSA, Castanet-Tolosan, France
| | - Renaud Brouquisse
- Institut Sophia Agrobiotech (ISA), INRAE, CNRS, Université Côte d'Azur, 06903 Sophia Antipolis Cedex, France
| | - Claude Bruand
- Laboratoire des Interactions Plantes-Microbes-Environnement (LIPME), Université de Toulouse, INRAE, CNRS, INSA, Castanet-Tolosan, France
| | - Eliane Meilhoc
- Laboratoire des Interactions Plantes-Microbes-Environnement (LIPME), Université de Toulouse, INRAE, CNRS, INSA, Castanet-Tolosan, France
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Shahid M, Zeyad MT, Syed A, Singh UB, Mohamed A, Bahkali AH, Elgorban AM, Pichtel J. Stress-Tolerant Endophytic Isolate Priestia aryabhattai BPR-9 Modulates Physio-Biochemical Mechanisms in Wheat ( Triticum aestivum L.) for Enhanced Salt Tolerance. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:10883. [PMID: 36078599 PMCID: PMC9518148 DOI: 10.3390/ijerph191710883] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Revised: 08/16/2022] [Accepted: 08/24/2022] [Indexed: 05/28/2023]
Abstract
In efforts to improve plant productivity and enhance defense mechanisms against biotic and abiotic stresses, endophytic bacteria have been used as an alternative to chemical fertilizers and pesticides. In the current study, 25 endophytic microbes recovered from plant organs of Triticum aestivum L. (wheat) were assessed for biotic (phyto-fungal pathogens) and abiotic (salinity, drought, and heavy metal) stress tolerance. Among the recovered isolates, BPR-9 tolerated maximum salinity (18% NaCl), drought (15% PEG-6000), and heavy metals (µg mL-1): Cd (1200), Cr (1000), Cu (1000), Pb (800), and Hg (30). Based on phenotypic and biochemical characteristics, as well as 16S rDNA gene sequencing, endophytic isolate BPR-9 was recognized as Priestia aryabhattai (accession no. OM743254.1). This isolate was revealed as a powerful multi-stress-tolerant crop growth promoter after extensive in-vitro testing for plant growth-promoting attributes, nutrient (phosphate, P; potassium, K; and zinc, Zn) solubilization efficiency, extracellular enzyme (protease, cellulase, amylase, lipase, and pectinase) synthesis, and potential for antagonistic activity against important fungal pathogens viz. Alternaria solani, Rhizoctonia solani, Fusarium oxysporum, and Ustilaginoidea virens. At elevated salt levels, increases were noted in indole-3-acetic acid; siderophores; P, K, and Zn-solubilization; ACC deaminase; and ammonia synthesized by Priestia aryabhattai. Additionally, under in-vitro plant bioassays, wheat seedlings inoculated with P. aryabhattai experienced superior growth compared to non-inoculated seedlings in high salinity (0-15% NaCl) environment. Under NaCl stress, germination rate, plant length, vigor indices, and leaf pigments of wheat seedlings significantly increased following P. aryabhattai inoculation. Furthermore, at 2%-NaCl, B. aryabhattai greatly and significantly (p ≤ 0.05) decreased relative leaf water content, membrane damage, and electrolyte leakage compared with the non-inoculated control. Catalase, superoxide dismutase, and peroxidase activity increased by 29, 32, and 21%, respectively, in wheat seedlings exposed to 2% NaCl and inoculated with the bacteria. The present findings demonstrate that endophytic P. aryabhattai strains might be used in the future as a multi-stress reducer and crop growth promoter in agronomically important crops including cereals.
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Affiliation(s)
- Mohammad Shahid
- Plant-Microbe Interaction and Rhizosphere Biology Lab, ICAR-National Bureau of Agriculturally Important Microorganisms (NBAIM), Mau 275103, India
- Department of Agricultural Microbiology, Faculty of Agricultural Sciences, Aligarh Muslim University, Aligarh 202002, India
| | - Mohammad Tarique Zeyad
- Department of Agricultural Microbiology, Faculty of Agricultural Sciences, Aligarh Muslim University, Aligarh 202002, India
- ICAR-National Bureau of Agriculturally Important Microorganisms (NBAIM), Mau 275103, India
| | - Asad Syed
- Department of Botany and Microbiology, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
| | - Udai B. Singh
- Plant-Microbe Interaction and Rhizosphere Biology Lab, ICAR-National Bureau of Agriculturally Important Microorganisms (NBAIM), Mau 275103, India
| | - Abdullah Mohamed
- Research Centre, Future University in Egypt, New Cairo 11835, Egypt
| | - Ali H. Bahkali
- Department of Botany and Microbiology, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
| | - Abdallah M. Elgorban
- Department of Botany and Microbiology, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
| | - John Pichtel
- Natural Resources and Environmental Management, Ball State University, Muncie, IN 47306, USA
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Shahid M, Al-Khattaf FS, Danish M, Zeyad MT, Atef Hatamleh A, Mohamed A, Ali S. PGPR Kosakonia Radicincitans KR-17 Increases the Salt Tolerance of Radish by Regulating Ion-Homeostasis, Photosynthetic Molecules, Redox Potential, and Stressor Metabolites. FRONTIERS IN PLANT SCIENCE 2022; 13:919696. [PMID: 35979076 PMCID: PMC9376370 DOI: 10.3389/fpls.2022.919696] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 06/10/2022] [Indexed: 05/10/2023]
Abstract
Among abiotic stresses, salinity is a significant limiting factor affecting agricultural productivity, survival, and production, resulting in significant economic losses. Considering the salinity problem, the goal of this study was to identify a halotolerant beneficial soil bacterium to circumvent salinity-induced phytotoxicity. Here, strain KR-17 (having an irregular margin; a mucoid colony; Gm-ve short rod; optimum temperature, 30°C; pH 7.0; no any pigmentation; showed a positive response to citrate utilization, catalase, starch, sucrose, lactose, and dextrose, etc.) recovered from rhizosphere soils of the potato-cultivating field, tolerated surprisingly a high (18% NaCl; 3.-M concentration) level of salt and identified as Kosakonia radicincitans (Accession No. OM348535). This strain was discovered to be metabolically active, synthesized essential PGP bioactive molecules like indole-3-acetic acid (IAA), siderophore (iron-chelating compounds), ACC deaminase, and ammonia, the quantity of which, however, increased with increasing NaCl concentrations. Here, Raphanus sativus L. (radish) was taken as a model crop to evaluate the adverse impact of NaCl, as well as salinity alleviation by halotolerant K. radicincitans. Salinity-induced toxicity to R. sativus was increased in a dose-dependent way, as observed both in vitro and in vivo conditions. Maximum NaCl levels (15%) demonstrated more extreme harm and considerably reduced the plant's biological features. However, membrane damage, relative leaf water content (RLWC), stressor metabolites, and antioxidant enzymes were increased as NaCl concentration increased. In contrast, halotolerant K. radicincitans KR-17 relieved salinity stress and enhanced the overall performance of R. sativus (L.) by increasing germination efficiency, dry biomass, and leaf pigments even in salt-challenged conditions. Additionally, KR-17 inoculation significantly (p ≤ 0.05) improved plant mineral nutrients (Na, K, Ca, Mg, Zn, Fe, Cu, P, and N). Following inoculation, strain KR-17 enhanced the protein, carbohydrates, root pigments, amino acids (AsA and Lys), lipids, and root alkaloids in R. sativus (L.). Besides these, due to PGPR seed priming in NaCl-stressed/non-stressed conditions, membrane damage, RLWC, stressor metabolites, and antioxidant defense enzymes were dramatically reduced. The strong biofilm-forming capacity of K. radicincitans could result in both in vitro and in vivo colonization under NaCl stress. Conclusively, halotolerant K. radicincitans KR-17 may probably be investigated affordably as the greatest way to increase the production of radish under salinity-stressed soils.
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Affiliation(s)
- Mohammad Shahid
- Department of Agricultural Microbiology, Faculty of Agricultural Sciences, Aligarh Muslim University, Aligarh, India
| | - Fatimah S. Al-Khattaf
- Department of Botany and Microbiology, College of Sciences, King Saud University, Riyadh, Saudi Arabia
| | - Mohammad Danish
- Section of Plant Pathology and Nematology, Department of Botany, Aligarh Muslim University, Aligarh, India
| | | | - Ashraf Atef Hatamleh
- Department of Botany and Microbiology, College of Sciences, King Saud University, Riyadh, Saudi Arabia
| | | | - Sajad Ali
- Department of Biotechnology, Yeungnam University, Gyeongsan, South Korea
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Al-Shwaiman HA, Shahid M, Elgorban AM, Siddique KHM, Syed A. Beijerinckia fluminensis BFC-33, a novel multi-stress-tolerant soil bacterium: Deciphering the stress amelioration, phytopathogenic inhibition and growth promotion in Triticum aestivum (L.). CHEMOSPHERE 2022; 295:133843. [PMID: 35122822 DOI: 10.1016/j.chemosphere.2022.133843] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 01/28/2022] [Accepted: 01/31/2022] [Indexed: 05/16/2023]
Abstract
Environmental challenges like drought, salinity, heavy metals and pesticides directly/indirectly influence the environment and decreased the agricultural output. During its long developmental stages, cereal crops including wheat is exposed to a variety of abiotic/biotic stressors. Certain beneficial soil bacteria that can ameliorate environmental stresses can be exploited as crop growth promoters/enhancers under adverse situations. In this study, Beijerinckia fluminensis BFC-33 (accession no. MT672580) isolated from potato rhizosphere tolerated variousabiotic (drought, salinity, temperature, heavy metals, and fungicides) stresses. Strain BFC-33 demonstrated multifarious plant-growth-promoting (PGP) characteristics, such as the production of indole-3-acetic acid, P-solubilization, ACC deaminase, ammonia, siderophore, HCN, EPS, and extracellular enzymes. The antagonistic potential of BFC-33 against major fungal pathogens was ranked: Alternaria alternata (79.2%)>Rhizoctonia solani (69%)>Fusarium oxysporum (23.5%)>Ustilaginoidea virens (17%). Furthermore, bacterization of wheat seeds witha multi-stress-tolerant strain revealed B. fluminensis as a plant growth enhancer and biocontrol agent. For instance, increase in root length (cm) in BFC-33 inoculated wheat exposed to abiotic and biotic stresses at the seedling stage was ranked: B. fluminensis (24.2)>B. fluminensis + 100μgTBZLmL-1 (21.3) = B. fluminensis + 2%PEG (21.3)>B. fluminensis + 100 mM NaCl (19.7)>B. fluminensis + 100μgPbmL-1 (19) = B. fluminensis 100μgMNZBmL-1 (19)>B. fluminensis + A. alternata (17.4)>B. fluminensis + 100μgCdmL-1 (17)>B. fluminensis + F. oxysporum (13.4). In addition, increase in carotenoid accumulation (mg g-1FW) in the foliage of BFC-33 inoculated wheat exposed to fungal infection was ranked: BFC-33 (3.88)>BFC-33+ A. alternata (3.0)>BFC-33+ R. solani (2.78)>BFC-33+ F. oxysporum (2.44). Moreover, BFC-33 inoculation significantly (p ≤ 0.05) reduced stress-induced stressor molecules (proline and TBARS) and electrolyte leakage. Furthermore, B. fluminensis BFC-33 potentially enhanced the defense responses in wheat seedlings by increasing phenylalanine ammonia lyase (PAL), β-1,3 glucanase, and polyphenol oxidase (PPO), which play a significant role in protecting plants from phytopathogens. Even so, by successfully establishing a product with the requisite effects under field settings, selecting multi-stress-tolerant and antagonistic plant growth promoting rhizobacteria (PGPRs) would be helpful to end-users. Future use of native multi-stress-tolerant bacteria as biocontrol agents in conjunction with existing drought, salinity, heavy metal, and pesticide tolerance might contribute to global food security.
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Affiliation(s)
- Hind A Al-Shwaiman
- Department of Botany and Microbiology, College of Sciences, King Saud University, P.O. Box 2455, Riyadh, 11451, Saudi Arabia
| | - Mohammad Shahid
- Department of Agricultural Microbiology, Faculty of Agricultural Sciences, Aligarh Muslim University, Aligarh, 202002, Uttar Pradesh, India.
| | - Abdallah M Elgorban
- Department of Botany and Microbiology, College of Sciences, King Saud University, P.O. Box 2455, Riyadh, 11451, Saudi Arabia
| | - Kadambot H M Siddique
- The UWA Institute of Agriculture and School of Agriculture & Environment, The University of Western Australia, Perth, WA, 6001, Australia
| | - Asad Syed
- Department of Botany and Microbiology, College of Sciences, King Saud University, P.O. Box 2455, Riyadh, 11451, Saudi Arabia.
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20
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Plant-Microbe Interaction in Sustainable Agriculture: The Factors That May Influence the Efficacy of PGPM Application. SUSTAINABILITY 2022. [DOI: 10.3390/su14042253] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The indiscriminate use of chemical fertilizers and pesticides has caused considerable environmental damage over the years. However, the growing demand for food in the coming years and decades requires the use of increasingly productive and efficient agriculture. Several studies carried out in recent years have shown how the application of plant growth-promoting microbes (PGPMs) can be a valid substitute for chemical industry products and represent a valid eco-friendly alternative. However, because of the complexity of interactions created with the numerous biotic and abiotic factors (i.e., environment, soil, interactions between microorganisms, etc.), the different formulates often show variable effects. In this review, we analyze the main factors that influence the effectiveness of PGPM applications and some of the applications that make them a useful tool for agroecological transition.
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21
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Hagberg KL, Price JP, Yurgel SN, Kahn ML. The Sinorhizobium meliloti Nitrogen Stress Response Changes Radically in the Face of Concurrent Phosphate Stress. Front Microbiol 2022; 13:800146. [PMID: 35154051 PMCID: PMC8829014 DOI: 10.3389/fmicb.2022.800146] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 01/06/2022] [Indexed: 11/13/2022] Open
Abstract
Expression of hundreds of S. meliloti genes changed more than two-fold in response to either nitrogen or phosphate limitation. When these two stresses were applied together, stress responsive gene expression shifted dramatically. In particular, the nitrogen stress response in the presence of phosphate stress had only 30 of about 350 genes in common with the 280 genes that responded to nitrogen stress with adequate phosphate. Expression of sRNAs was also altered in response to these stresses. 82% of genes that responded to nitrogen stress also responded to phosphate stress, including 20 sRNAs. A subset of these sRNAs is known to be chaperoned by the RNA binding protein, Hfq. Hfq had previously been shown to influence about a third of the genes that responded to both nitrogen and phosphate stresses. Phosphate limitation influenced changes in gene expression more than nitrogen limitation and, when both stresses were present, phosphate stress sometimes reversed the direction of some of the changes induced by nitrogen stress. These nutrient stress responses are therefore context dependent.
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Affiliation(s)
- Kelly L. Hagberg
- School of Molecular Biosciences, Institute of Biological Chemistry, Washington State University, Pullman, WA, United States
| | - Jason P. Price
- School of Molecular Biosciences, Institute of Biological Chemistry, Washington State University, Pullman, WA, United States
| | - Svetlana N. Yurgel
- School of Molecular Biosciences, Institute of Biological Chemistry, Washington State University, Pullman, WA, United States
- Department of Plant, Food and Environmental Sciences, Dalhousie University, Truro, NS, Canada
| | - Michael L. Kahn
- School of Molecular Biosciences, Institute of Biological Chemistry, Washington State University, Pullman, WA, United States
- *Correspondence: Michael L. Kahn,
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Shahid M, Khan MS. Tolerance of pesticides and antibiotics among beneficial soil microbes recovered from contaminated rhizosphere of edible crops. CURRENT RESEARCH IN MICROBIAL SCIENCES 2022; 3:100091. [PMID: 34977827 PMCID: PMC8683648 DOI: 10.1016/j.crmicr.2021.100091] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Revised: 12/02/2021] [Accepted: 12/06/2021] [Indexed: 12/20/2022] Open
Abstract
Soil bacterial isolates were recovered from contaminated rhizosphere regions. Majority of bacterial isolatesshowed multifarious plant growth promoting (PGP) activities. Bacterial isolates exhibited a varied level of pesticide tolerance. Sensitivity/resistance pattern among isolates was variable Pesticides tolerance and antibiotic resistance among soil isolates were variably correlated
A total of 45 beneficial soil bacterial isolates (15 each of Pseudomonas, Azotobacter and phosphate solubilizing bacteria: PSB) recovered from polluted rhizosphere soils were morphologically and biochemically characterized. Bacterial isolates produced indole-3-acetic acid (IAA), phenolate siderophores; SA (salicylic acid) and 2, 3-dihydroxy benzoic acid (2, 3-DHBA), 1-amino cyclopropane 1-carboxylate (ACC) deaminase, solubilised insoluble phosphate (Pi), secreted exopolysaccharides (EPS) and produced ammonia and cyanogenic compound (HCN). Isolates were tested for their tolerance ability against 12 different agrochemicals (chemical pesticides) and 14 antibiotics. Among Pseudomonas, isolate PS1 showed maximum (2183 µg mL−1) tolerance to all tested agrochemicals. Likewise, among all Azotobacter isolates (n = 15), AZ12 showed maximum (1766 µg mL−1) while AZ7 had lowest (950 µg mL−1) tolerance ability to all tested agrochemicals. Moreover, among phosphate solubilizing bacterial isolates, maximum (1970 µg mL−1) and minimum (1308 µg mL−1) tolerance to agrochemicals was represented by PSB8 and PSB13 isolates, respectively. The antibiotic sensitivity/resistance among isolates varied considerably. As an example, Pseudomonas spp. was susceptible to several antibiotics, and inhibition zone differed between 10 mm (polymyxin B) to 34 mm (nalidixic acid). Also, isolate PS2 showed resistance to erythromycin, ciprofloxacin, methicillin, novobiocin and penicillin. The resistance percentage to multiple antibiotics among Azotobacter isolates varied between 7 and 33%. Among PSB isolates, inhibition zone differed between 10 and 40 mm and maximum and minimum resistance percentage to multiple antibiotics was recorded as 47% and 20%, respectively. The persistence of pesticides in agricultural soil may contribute to an increase in multidrug resistance among soil microorganisms. In conclusion, plant growth promoting (PGP) substances releasing soil microorganisms comprising of inherent/intrinsic properties of pesticides tolerance and antibiotics resistance may provide an attractive, agronomically feasible, and long-term prospective alternative for the augmentation of edible crops. However, in future, more research is needed to uncover the molecular processes behind the development of pesticide tolerance and antibiotic resistance among soil microorganisms.
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Affiliation(s)
- Mohammad Shahid
- Department of Agricultural Microbiology, Faculty of Agricultural Sciences, Aligarh Muslim University, Aligarh-202002, Uttar Pradesh, India
| | - Mohammad Saghir Khan
- Department of Agricultural Microbiology, Faculty of Agricultural Sciences, Aligarh Muslim University, Aligarh-202002, Uttar Pradesh, India
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Yurgel SN, Qu Y, Rice JT, Ajeethan N, Zink EM, Brown JM, Purvine S, Lipton MS, Kahn ML. Specialization in a Nitrogen-Fixing Symbiosis: Proteome Differences Between Sinorhizobium medicae Bacteria and Bacteroids. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2021; 34:1409-1422. [PMID: 34402628 DOI: 10.1094/mpmi-07-21-0180-r] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Using tandem mass spectrometry (MS/MS), we analyzed the proteome of Sinorhizobium medicae WSM419 growing as free-living cells and in symbiosis with Medicago truncatula. In all, 3,215 proteins were identified, over half of the open reading frames predicted from the genomic sequence. The abundance of 1,361 proteins displayed strong lifestyle bias. In total, 1,131 proteins had similar levels in bacteroids and free-living cells, and the low levels of 723 proteins prevented statistically significant assignments. Nitrogenase subunits comprised approximately 12% of quantified bacteroid proteins. Other major bacteroid proteins included symbiosis-specific cytochromes and FixABCX, which transfer electrons to nitrogenase. Bacteroids had normal levels of proteins involved in amino acid biosynthesis, glycolysis or gluconeogenesis, and the pentose phosphate pathway; however, several amino acid degradation pathways were repressed. This suggests that bacteroids maintain a relatively independent anabolic metabolism. Tricarboxylic acid cycle proteins were highly expressed in bacteroids and no other catabolic pathway emerged as an obvious candidate to supply energy and reductant to nitrogen fixation. Bacterial stress response proteins were induced in bacteroids. Many WSM419 proteins that are not encoded in S. meliloti Rm1021 were detected, and understanding the functions of these proteins might clarify why S. medicae WSM419 forms a more effective symbiosis with M. truncatula than S. meliloti Rm1021.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Svetlana N Yurgel
- Department of Plant, Food and Environmental Sciences, Faculty of Agriculture, Dalhousie University, P.O. Box 550, Truro, Nova Scotia, B2N 5E3, Canada
- Institute of Biological Chemistry, Washington State University, Pullman, WA 99164-6340, U.S.A
| | - Yi Qu
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352, U.S.A
| | - Jennifer T Rice
- Institute of Biological Chemistry, Washington State University, Pullman, WA 99164-6340, U.S.A
| | - Nivethika Ajeethan
- Department of Plant, Food and Environmental Sciences, Faculty of Agriculture, Dalhousie University, P.O. Box 550, Truro, Nova Scotia, B2N 5E3, Canada
- Faculty of Technology, University of Jaffna, Sri Lanka
| | - Erika M Zink
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352, U.S.A
| | - Joseph M Brown
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352, U.S.A
| | - Sam Purvine
- Environmental Molecular Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352, U.S.A
| | - Mary S Lipton
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352, U.S.A
| | - Michael L Kahn
- Institute of Biological Chemistry, Washington State University, Pullman, WA 99164-6340, U.S.A
- School of Molecular Biosciences, Washington State University, Pullman, WA 99164-6340, U.S.A
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24
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Basile LA, Lepek VC. Legume-rhizobium dance: an agricultural tool that could be improved? Microb Biotechnol 2021; 14:1897-1917. [PMID: 34318611 PMCID: PMC8449669 DOI: 10.1111/1751-7915.13906] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 07/15/2021] [Accepted: 07/19/2021] [Indexed: 12/29/2022] Open
Abstract
The specific interaction between rhizobia and legume roots leads to the development of a highly regulated process called nodulation, by which the atmospheric nitrogen is converted into an assimilable plant nutrient. This capacity is the basis for the use of bacterial inoculants for field crop cultivation. Legume plants have acquired tools that allow the entry of compatible bacteria. Likewise, plants can impose sanctions against the maintenance of nodules occupied by rhizobia with low nitrogen-fixing capacity. At the same time, bacteria must overcome different obstacles posed first by the environment and then by the legume. The present review describes the mechanisms involved in the regulation of the entire legume-rhizobium symbiotic process and the strategies and tools of bacteria for reaching the nitrogen-fixing state inside the nodule. Also, we revised different approaches to improve the nodulation process for a better crop yield.
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Affiliation(s)
- Laura A. Basile
- Instituto de Investigaciones Biotecnológicas “Dr. Rodolfo A. Ugalde”Universidad Nacional de San Martín (IIB‐UNSAM‐CONICET)Av. 25 de Mayo y Francia, Gral. San Martín, Provincia de Buenos AiresBuenos AiresB1650HMPArgentina
| | - Viviana C. Lepek
- Instituto de Investigaciones Biotecnológicas “Dr. Rodolfo A. Ugalde”Universidad Nacional de San Martín (IIB‐UNSAM‐CONICET)Av. 25 de Mayo y Francia, Gral. San Martín, Provincia de Buenos AiresBuenos AiresB1650HMPArgentina
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25
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Schulte CCM, Borah K, Wheatley RM, Terpolilli JJ, Saalbach G, Crang N, de Groot DH, Ratcliffe RG, Kruger NJ, Papachristodoulou A, Poole PS. Metabolic control of nitrogen fixation in rhizobium-legume symbioses. SCIENCE ADVANCES 2021; 7:7/31/eabh2433. [PMID: 34330708 PMCID: PMC8324050 DOI: 10.1126/sciadv.abh2433] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 06/14/2021] [Indexed: 05/16/2023]
Abstract
Rhizobia induce nodule formation on legume roots and differentiate into bacteroids, which catabolize plant-derived dicarboxylates to reduce atmospheric N2 into ammonia. Despite the agricultural importance of this symbiosis, the mechanisms that govern carbon and nitrogen allocation in bacteroids and promote ammonia secretion to the plant are largely unknown. Using a metabolic model derived from genome-scale datasets, we show that carbon polymer synthesis and alanine secretion by bacteroids facilitate redox balance in microaerobic nodules. Catabolism of dicarboxylates induces not only a higher oxygen demand but also a higher NADH/NAD+ ratio than sugars. Modeling and 13C metabolic flux analysis indicate that oxygen limitation restricts the decarboxylating arm of the tricarboxylic acid cycle, which limits ammonia assimilation into glutamate. By tightly controlling oxygen supply and providing dicarboxylates as the energy and electron source donors for N2 fixation, legumes promote ammonia secretion by bacteroids. This is a defining feature of rhizobium-legume symbioses.
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Affiliation(s)
- Carolin C M Schulte
- Department of Plant Sciences, University of Oxford, Oxford, UK
- Department of Engineering Science, University of Oxford, Oxford, UK
| | - Khushboo Borah
- Department of Plant Sciences, University of Oxford, Oxford, UK
| | | | | | | | - Nick Crang
- Department of Plant Sciences, University of Oxford, Oxford, UK
| | - Daan H de Groot
- Systems Biology Lab, AIMMS, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
| | | | | | | | - Philip S Poole
- Department of Plant Sciences, University of Oxford, Oxford, UK.
- John Innes Centre, Norwich Research Park, Norwich, UK
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26
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Bueno Batista M, Brett P, Appia-Ayme C, Wang YP, Dixon R. Disrupting hierarchical control of nitrogen fixation enables carbon-dependent regulation of ammonia excretion in soil diazotrophs. PLoS Genet 2021; 17:e1009617. [PMID: 34111137 PMCID: PMC8219145 DOI: 10.1371/journal.pgen.1009617] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 06/22/2021] [Accepted: 05/23/2021] [Indexed: 12/14/2022] Open
Abstract
The energetic requirements for biological nitrogen fixation necessitate stringent regulation of this process in response to diverse environmental constraints. To ensure that the nitrogen fixation machinery is expressed only under appropriate physiological conditions, the dedicated NifL-NifA regulatory system, prevalent in Proteobacteria, plays a crucial role in integrating signals of the oxygen, carbon and nitrogen status to control transcription of nitrogen fixation (nif) genes. Greater understanding of the intricate molecular mechanisms driving transcriptional control of nif genes may provide a blueprint for engineering diazotrophs that associate with cereals. In this study, we investigated the properties of a single amino acid substitution in NifA, (NifA-E356K) which disrupts the hierarchy of nif regulation in response to carbon and nitrogen status in Azotobacter vinelandii. The NifA-E356K substitution enabled overexpression of nitrogenase in the presence of excess fixed nitrogen and release of ammonia outside the cell. However, both of these properties were conditional upon the nature of the carbon source. Our studies reveal that the uncoupling of nitrogen fixation from its assimilation is likely to result from feedback regulation of glutamine synthetase, allowing surplus fixed nitrogen to be excreted. Reciprocal substitutions in NifA from other Proteobacteria yielded similar properties to the A. vinelandii counterpart, suggesting that this variant protein may facilitate engineering of carbon source-dependent ammonia excretion amongst diverse members of this family.
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Affiliation(s)
| | - Paul Brett
- Department of Metabolic Biology, John Innes Centre, Norwich, United Kingdom
| | - Corinne Appia-Ayme
- Department of Molecular Microbiology, John Innes Centre, Norwich, United Kingdom
| | - Yi-Ping Wang
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences & School of Advanced Agricultural Sciences, Peking University, Beijing, China
| | - Ray Dixon
- Department of Molecular Microbiology, John Innes Centre, Norwich, United Kingdom
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27
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Gavrin A, Loughlin PC, Brear E, Griffith OW, Bedon F, Suter Grotemeyer M, Escudero V, Reguera M, Qu Y, Mohd-Noor SN, Chen C, Osorio MB, Rentsch D, González-Guerrero M, Day DA, Smith PMC. Soybean Yellow Stripe-like 7 is a symbiosome membrane peptide transporter important for nitrogen fixation. PLANT PHYSIOLOGY 2021; 186:581-598. [PMID: 33619553 PMCID: PMC8154080 DOI: 10.1093/plphys/kiab044] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 01/21/2021] [Indexed: 05/05/2023]
Abstract
Legumes form a symbiosis with rhizobia that convert atmospheric nitrogen (N2) to ammonia and provide it to the plant in return for a carbon and nutrient supply. Nodules, developed as part of the symbiosis, harbor rhizobia that are enclosed in a plant-derived symbiosome membrane (SM) to form an organelle-like structure called the symbiosome. In mature nodules exchanges between the symbionts occur across the SM. Here we characterize Yellow Stripe-like 7 (GmYSL7), a Yellow stripe-like family member localized on the SM in soybean (Glycine max) nodules. It is expressed specifically in infected cells with expression peaking soon after nitrogenase becomes active. Unlike most YSL family members, GmYSL7 does not transport metals complexed with phytosiderophores. Rather, it transports oligopeptides of between four and 12 amino acids. Silencing GmYSL7 reduces nitrogenase activity and blocks infected cell development so that symbiosomes contain only a single bacteroid. This indicates the substrate of YSL7 is required for proper nodule development, either by promoting symbiosome development directly or by preventing inhibition of development by the plant. RNAseq of nodules where GmYSL7 was silenced suggests that the plant initiates a defense response against rhizobia with genes encoding proteins involved in amino acid export downregulated and some transcripts associated with metal homeostasis altered. These changes may result from the decrease in nitrogen fixation upon GmYSL7 silencing and suggest that the peptide(s) transported by GmYSL7 monitor the functional state of the bacteroids and regulate nodule metabolism and transport processes accordingly. Further work to identify the physiological substrate for GmYSL7 will allow clarification of this role.
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Affiliation(s)
- Aleksandr Gavrin
- Sainsbury Laboratory, University of Cambridge, Cambridge CB2 1LR, UK
| | - Patrick C Loughlin
- School of Life and Environmental Science, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Ella Brear
- School of Life and Environmental Science, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Oliver W Griffith
- Department of Biological Sciences, Macquarie University, Macquarie Park, NSW 2109, Australia
| | - Frank Bedon
- School of Life Sciences, La Trobe University, Bundoora, Victoria 3083, Australia
| | | | - Viviana Escudero
- Centro de Biotecnología y Genómica de Plantas (UPM-INIA). Universidad Politécnica de Madrid, Campus de Montegancedo, Crta, 28223 Pozuelo de Alarcón (Madrid), Spain
| | - Maria Reguera
- Centro de Biotecnología y Genómica de Plantas (UPM-INIA). Universidad Politécnica de Madrid, Campus de Montegancedo, Crta, 28223 Pozuelo de Alarcón (Madrid), Spain
| | - Yihan Qu
- School of Life and Environmental Science, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Siti N Mohd-Noor
- School of Life and Environmental Science, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Chi Chen
- School of Life and Environmental Science, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Marina Borges Osorio
- School of Life Sciences, La Trobe University, Bundoora, Victoria 3083, Australia
| | - Doris Rentsch
- IPS, Molecular Plant Physiology, University of Bern, Altenbergrain 21, 3013 Bern, Switzerland
| | - Manuel González-Guerrero
- Centro de Biotecnología y Genómica de Plantas (UPM-INIA). Universidad Politécnica de Madrid, Campus de Montegancedo, Crta, 28223 Pozuelo de Alarcón (Madrid), Spain
| | - David A Day
- College of Science and Engineering, Flinders University, Bedford Park, Adelaide, SA, Australia
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28
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Pérez-Giménez J, Iturralde ET, Torres Tejerizo G, Quelas JI, Krol E, Borassi C, Becker A, Estevez JM, Lodeiro AR. A Stringent-Response-Defective Bradyrhizobium diazoefficiens Strain Does Not Activate the Type 3 Secretion System, Elicits an Early Plant Defense Response, and Circumvents NH 4NO 3-Induced Inhibition of Nodulation. Appl Environ Microbiol 2021; 87:e02989-20. [PMID: 33608284 PMCID: PMC8091029 DOI: 10.1128/aem.02989-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 02/08/2021] [Indexed: 12/30/2022] Open
Abstract
When subjected to nutritional stress, bacteria modify their amino acid metabolism and cell division activities by means of the stringent response, which is controlled by the Rsh protein in alphaproteobacteria. An important group of alphaproteobacteria are the rhizobia, which fix atmospheric N2 in symbiosis with legume plants. Although nutritional stress is common for rhizobia while infecting legume roots, the stringent response has scarcely been studied in this group of soil bacteria. In this report, we obtained a mutant with a kanamycin resistance insertion in the rsh gene of Bradyrhizobium diazoefficiens, the N2-fixing symbiont of soybean. This mutant was defective for type 3 secretion system induction, plant defense suppression at early root infection, and nodulation competition. Furthermore, the mutant produced smaller nodules, although with normal morphology, which led to lower plant biomass production. Soybean (Glycine max) genes GmRIC1 and GmRIC2, involved in autoregulation of nodulation, were upregulated in plants inoculated with the mutant under the N-free condition. In addition, when plants were inoculated in the presence of 10 mM NH4NO3, the mutant produced nodules containing bacteroids, and GmRIC1 and GmRIC2 were downregulated. The rsh mutant released more auxin to the culture supernatant than the wild type, which might in part explain its symbiotic behavior in the presence of combined N. These results indicate that the B. diazoefficiens stringent response integrates into the plant defense suppression and regulation of nodulation circuits in soybean, perhaps mediated by the type 3 secretion system.IMPORTANCE The symbiotic N2 fixation carried out between prokaryotic rhizobia and legume plants performs a substantial contribution to the N cycle in the biosphere. This symbiotic association is initiated when rhizobia infect and penetrate the root hairs, which is followed by the growth and development of root nodules, within which the infective rhizobia are established and protected. Thus, the nodule environment allows the expression and function of the enzyme complex that catalyzes N2 fixation. However, during early infection, the rhizobia find a harsh environment while penetrating the root hairs. To cope with this nuisance, the rhizobia mount a stress response known as the stringent response. In turn, the plant regulates nodulation in response to the presence of alternative sources of combined N in the surrounding medium. Control of these processes is crucial for a successful symbiosis, and here we show how the rhizobial stringent response may modulate plant defense suppression and the networks of regulation of nodulation.
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Affiliation(s)
- Julieta Pérez-Giménez
- IBBM, Facultad de Ciencias Exactas, CCT-La Plata CONICET, Universidad Nacional de La Plata, La Plata, Argentina
| | - Esteban T Iturralde
- IBBM, Facultad de Ciencias Exactas, CCT-La Plata CONICET, Universidad Nacional de La Plata, La Plata, Argentina
| | - Gonzalo Torres Tejerizo
- IBBM, Facultad de Ciencias Exactas, CCT-La Plata CONICET, Universidad Nacional de La Plata, La Plata, Argentina
| | - Juan Ignacio Quelas
- IBBM, Facultad de Ciencias Exactas, CCT-La Plata CONICET, Universidad Nacional de La Plata, La Plata, Argentina
| | - Elizaveta Krol
- Center for Synthetic Microbiology (SYNMIKRO), Department of Biology, Philipps-Universität Marburg, Marburg, Germany
| | - Cecilia Borassi
- Fundación Instituto Leloir, Instituto de Investigaciones Bioquímicas de Buenos Aires-CONICET, Buenos Aires, Argentina
| | - Anke Becker
- Center for Synthetic Microbiology (SYNMIKRO), Department of Biology, Philipps-Universität Marburg, Marburg, Germany
| | - José M Estevez
- Fundación Instituto Leloir, Instituto de Investigaciones Bioquímicas de Buenos Aires-CONICET, Buenos Aires, Argentina
- Centro de Biotecnología Vegetal, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
- Millennium Institute for Integrative Biology (iBio), Santiago, Chile
| | - Aníbal R Lodeiro
- IBBM, Facultad de Ciencias Exactas, CCT-La Plata CONICET, Universidad Nacional de La Plata, La Plata, Argentina
- Laboratorio de Genética, Facultad de Ciencias Agrarias y Forestales, Universidad Nacional de La Plata, La Plata, Argentina
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29
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Sun Y, Wang M, Mur LAJ, Shen Q, Guo S. The cross-kingdom roles of mineral nutrient transporters in plant-microbe relations. PHYSIOLOGIA PLANTARUM 2021; 171:771-784. [PMID: 33341944 DOI: 10.1111/ppl.13318] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 11/27/2020] [Indexed: 05/23/2023]
Abstract
The regulation of plant physiology by plant mineral nutrient transporter (MNT) is well understood. Recently, the extensive characterization of beneficial and pathogenic plant-microbe interactions has defined the roles for MNTs in such relationships. In this review, we summarize the roles of diverse nutrient transporters in the symbiotic or pathogenic relationships between plants and microorganisms. In doing so, we highlight how MNTs of plants and microbes can act in a coordinated manner. In symbiotic relationships, MNTs play key roles in the establishment of the interaction between the host plant and rhizobium or mycorrhizae as well in the subsequent coordinated transport of nutrients. Additionally, MNTs may also regulate the colonization or degeneration of symbiotic microorganisms by reflecting the nutrient status of the plant and soil. This allows the host plant obtain nutrients from the soil in the most optimal manner. With pathogenic-interactions, MNTs influence pathogen proliferation, the efficacy of the host's biochemical defense and related signal transduction mechanisms. We classify the MNT effects in plant-pathogen interactions as either indirect by influencing the nutrient status and fitness of the pathogen, or direct by initiating host defense mechanisms. While such observations indicate the fundamental importance of MNTs in governing the interactions with a range of microorganisms, further work is needed to develop an integrative understanding of their functions.
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Affiliation(s)
- Yuming Sun
- Jiangsu Provincial Key Lab of Solid Organic Waste Utilization, Jiangsu Collaborative Innovation Center of Solid Organic Wastes, Educational Ministry Engineering Center of Resource-saving fertilizers, Nanjing Agricultural University, Nanjing, China
- Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing, China
| | - Min Wang
- Jiangsu Provincial Key Lab of Solid Organic Waste Utilization, Jiangsu Collaborative Innovation Center of Solid Organic Wastes, Educational Ministry Engineering Center of Resource-saving fertilizers, Nanjing Agricultural University, Nanjing, China
| | - Luis Alejandro Jose Mur
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, UK
| | - Qirong Shen
- Jiangsu Provincial Key Lab of Solid Organic Waste Utilization, Jiangsu Collaborative Innovation Center of Solid Organic Wastes, Educational Ministry Engineering Center of Resource-saving fertilizers, Nanjing Agricultural University, Nanjing, China
| | - Shiwei Guo
- Jiangsu Provincial Key Lab of Solid Organic Waste Utilization, Jiangsu Collaborative Innovation Center of Solid Organic Wastes, Educational Ministry Engineering Center of Resource-saving fertilizers, Nanjing Agricultural University, Nanjing, China
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30
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Pervasive RNA Regulation of Metabolism Enhances the Root Colonization Ability of Nitrogen-Fixing Symbiotic α-Rhizobia. mBio 2021; 13:e0357621. [PMID: 35164560 PMCID: PMC8844928 DOI: 10.1128/mbio.03576-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The rhizosphere and rhizoplane are nutrient-rich but selective environments for the root microbiome. Here, we deciphered a posttranscriptional network regulated by the homologous trans-small RNAs (sRNAs) AbcR1 and AbcR2, which rewire the metabolism of the nitrogen-fixing α-rhizobium Sinorhizobium meliloti during preinfection stages of symbiosis with its legume host alfalfa. The LysR-type regulator LsrB, which transduces the cell redox state, is indispensable for AbcR1 expression in actively dividing bacteria, whereas the stress-induced transcription of AbcR2 depends on the alternative σ factor RpoH1. MS2 affinity purification coupled with RNA sequencing unveiled exceptionally large and overlapping AbcR1/2 mRNA interactomes, jointly representing ⁓6% of the S. meliloti protein-coding genes. Most mRNAs encode transport/metabolic proteins whose translation is silenced by base pairing to two distinct anti-Shine Dalgarno motifs that function independently in both sRNAs. A metabolic model-aided analysis of the targetomes predicted changes in AbcR1/2 expression driven by shifts in carbon/nitrogen sources, which were confirmed experimentally. Low AbcR1/2 levels in some defined media anticipated overexpression growth phenotypes linked to the silencing of specific mRNAs. As a proof of principle, we confirmed AbcR1/2-mediated downregulation of the l-amino acid AapQ permease. AbcR1/2 interactomes are well represented in rhizosphere-related S. meliloti transcriptomic signatures. Remarkably, a lack of AbcR1 specifically compromised the ability of S. meliloti to colonize the root rhizoplane. The AbcR1 regulon likely ranks the utilization of available substrates to optimize metabolism, thus conferring on S. meliloti an advantage for efficient rhizosphere/rhizoplane colonization. AbcR1 regulation is predicted to be conserved in related α-rhizobia, which opens unprecedented possibilities for engineering highly competitive biofertilizers. IMPORTANCE Nitrogen-fixing root nodule symbioses between rhizobia and legume plants provide more than half of the combined nitrogen incorporated annually into terrestrial ecosystems, rendering plant growth independent of environmentally unfriendly chemical fertilizers. The success of symbiosis depends primarily on the capacity of rhizobia to establish competitive populations in soil and rhizosphere environments. Here, we provide insights into the regulation and architecture of an extensive RNA posttranscriptional network that fine-tunes the metabolism of the alfalfa symbiont S. meliloti, thereby enhancing the ability of this beneficial bacterium to colonize nutrient-rich but extremely selective niches, such as the rhizosphere of its host plant. This pervasive RNA regulation of metabolism is a major adaptive mechanism, predicted to operate in diverse rhizobial species. Because RNA regulation relies on modifiable base-pairing interactions, our findings open unexplored avenues for engineering the legumes rhizobiome within sustainable agricultural practices.
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Abstract
Rhizobia are a phylogenetically diverse group of soil bacteria that engage in mutualistic interactions with legume plants. Although specifics of the symbioses differ between strains and plants, all symbioses ultimately result in the formation of specialized root nodule organs which host the nitrogen-fixing microsymbionts called bacteroids. Inside nodules, bacteroids encounter unique conditions that necessitate global reprogramming of physiological processes and rerouting of their metabolism. Decades of research have addressed these questions using genetics, omics approaches, and more recently computational modelling. Here we discuss the common adaptations of rhizobia to the nodule environment that define the core principles of bacteroid functioning. All bacteroids are growth-arrested and perform energy-intensive nitrogen fixation fueled by plant-provided C4-dicarboxylates at nanomolar oxygen levels. At the same time, bacteroids are subject to host control and sanctioning that ultimately determine their fitness and have fundamental importance for the evolution of a stable mutualistic relationship.
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Ochieno DMW, Karoney EM, Muge EK, Nyaboga EN, Baraza DL, Shibairo SI, Naluyange V. Rhizobium-Linked Nutritional and Phytochemical Changes Under Multitrophic Functional Contexts in Sustainable Food Systems. FRONTIERS IN SUSTAINABLE FOOD SYSTEMS 2021. [DOI: 10.3389/fsufs.2020.604396] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Rhizobia are bacteria that exhibit both endophytic and free-living lifestyles. Endophytic rhizobial strains are widely known to infect leguminous host plants, while some do infect non-legumes. Infection of leguminous roots often results in the formation of root nodules. Associations between rhizobia and host plants may result in beneficial or non-beneficial effects. Such effects are linked to various biochemical changes that have far-reaching implications on relationships between host plants and the dependent multitrophic biodiversity. This paper explores relationships that exist between rhizobia and various plant species. Emphasis is on nutritional and phytochemical changes that occur in rhizobial host plants, and how such changes affect diverse consumers at different trophic levels. The purpose of this paper is to bring into context various aspects of such interactions that could improve knowledge on the application of rhizobia in different fields. The relevance of rhizobia in sustainable food systems is addressed in context.
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Granado-Rodríguez S, Bolaños L, Reguera M. MtNIP5;1, a novel Medicago truncatula boron diffusion facilitator induced under deficiency. BMC PLANT BIOLOGY 2020; 20:552. [PMID: 33297962 PMCID: PMC7724820 DOI: 10.1186/s12870-020-02750-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 11/22/2020] [Indexed: 05/26/2023]
Abstract
BACKGROUND Legumes comprise important crops that offer major agronomic benefits, including the capacity of establishing symbiosis with rhizobia, fixing atmospheric N2. It has been proven that legumes are particularly susceptible to boron (B) stress, which leads to important yield penalties. Boron (B) deficiency or toxicity in plants causes the inhibition of growth and an altered development. Under such conditions, the participation of two distinct protein families (the major intrinsic protein family MIP and the Boron transporter family BOR) is required to minimize detrimental effects caused by B stress. However, in legumes, little is known about the transport mechanisms responsible for B uptake and distribution, especially under deficiency. RESULTS A Medicago truncatula protein, MtNIP5;1 (Medtr1g097840) (homologous to the Arabidopsis thaliana AtNIP5;1) was identified as a novel legume B transporter involved in B uptake under deficiency. Further analyses revealed that this M. truncatula aquaporin expression was boron-regulated in roots, being induced under deficiency and repressed under toxicity. It localizes at the plasma membrane of root epidermal cells and in nodules, where B plays pivotal roles in symbiosis. Furthermore, the partial complementation of the nip5;1-1 A. thaliana mutant phenotype under B deficiency supports a functional role of MtNIP5;1 as a B transporter in this legume model plant. CONCLUSIONS The results here presented support a functional role of MtNIP5;1 in B uptake under deficiency and provides new insights into B transport mechanisms in legume species.
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Affiliation(s)
- Sara Granado-Rodríguez
- Departamento de Biología, Universidad Autónoma de Madrid, c/Darwin 2, Campus de Cantoblanco, 28049, Madrid, Spain
| | - Luis Bolaños
- Departamento de Biología, Universidad Autónoma de Madrid, c/Darwin 2, Campus de Cantoblanco, 28049, Madrid, Spain
| | - Maria Reguera
- Departamento de Biología, Universidad Autónoma de Madrid, c/Darwin 2, Campus de Cantoblanco, 28049, Madrid, Spain.
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Inomura K, Deutsch C, Masuda T, Prášil O, Follows MJ. Quantitative models of nitrogen-fixing organisms. Comput Struct Biotechnol J 2020; 18:3905-3924. [PMID: 33335688 PMCID: PMC7733014 DOI: 10.1016/j.csbj.2020.11.022] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 11/11/2020] [Accepted: 11/13/2020] [Indexed: 10/26/2022] Open
Abstract
Nitrogen-fixing organisms are of importance to the environment, providing bioavailable nitrogen to the biosphere. Quantitative models have been used to complement the laboratory experiments and in situ measurements, where such evaluations are difficult or costly. Here, we review the current state of the quantitative modeling of nitrogen-fixing organisms and ways to enhance the bridge between theoretical and empirical studies.
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Affiliation(s)
- Keisuke Inomura
- School of Oceanography, University of Washington, Seattle, WA, USA
| | - Curtis Deutsch
- School of Oceanography, University of Washington, Seattle, WA, USA
| | - Takako Masuda
- Institute of Microbiology, The Czech Academy of Sciences, Opatovický mlýn, Třeboň, Czech Republic
| | - Ondřej Prášil
- Institute of Microbiology, The Czech Academy of Sciences, Opatovický mlýn, Třeboň, Czech Republic
| | - Michael J. Follows
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
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Riboregulation in Nitrogen-Fixing Endosymbiotic Bacteria. Microorganisms 2020; 8:microorganisms8030384. [PMID: 32164262 PMCID: PMC7143759 DOI: 10.3390/microorganisms8030384] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 03/04/2020] [Accepted: 03/05/2020] [Indexed: 01/21/2023] Open
Abstract
Small non-coding RNAs (sRNAs) are ubiquitous components of bacterial adaptive regulatory networks underlying stress responses and chronic intracellular infection of eukaryotic hosts. Thus, sRNA-mediated regulation of gene expression is expected to play a major role in the establishment of mutualistic root nodule endosymbiosis between nitrogen-fixing rhizobia and legume plants. However, knowledge about this level of genetic regulation in this group of plant-interacting bacteria is still rather scarce. Here, we review insights into the rhizobial non-coding transcriptome and sRNA-mediated post-transcriptional regulation of symbiotic relevant traits such as nutrient uptake, cell cycle, quorum sensing, or nodule development. We provide details about the transcriptional control and protein-assisted activity mechanisms of the functionally characterized sRNAs involved in these processes. Finally, we discuss the forthcoming research on riboregulation in legume symbionts.
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Yoneyama T, Terakado-Tonooka J, Bao Z, Minamisawa K. Molecular Analyses of the Distribution and Function of Diazotrophic Rhizobia and Methanotrophs in the Tissues and Rhizosphere of Non-Leguminous Plants. PLANTS 2019; 8:plants8100408. [PMID: 31614562 PMCID: PMC6843303 DOI: 10.3390/plants8100408] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2019] [Revised: 09/26/2019] [Accepted: 10/10/2019] [Indexed: 01/16/2023]
Abstract
Biological nitrogen fixation (BNF) by plants and its bacterial associations represent an important natural system for capturing atmospheric dinitrogen (N2) 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 N2 fixation in non-leguminous plants. Identification of the involved N2-fixing bacteria has also been difficult because the major nitrogen fixers were often lost during isolation attempts. The past 20 years of molecular analyses has led to the identification of N2 fixation sites and active nitrogen fixers in tissues and the rhizosphere of non-leguminous plants. Here, we examined BNF hotspots in six reported non-leguminous plants. Novel rhizobia and methanotrophs were found to be abundantly present in the free-living state at sites where carbon and energy sources were predominantly available. In the carbon-rich apoplasts of plant tissues, rhizobia such as Bradyrhizobium spp. microaerobically fix N2. In paddy rice fields, methane molecules generated under anoxia are oxidized by xylem aerenchyma-transported oxygen with the simultaneous fixation of N2 by methane-oxidizing methanotrophs. We discuss the effective functions of the rhizobia and methanotrophs in non-legumes for the acquisition of fixed nitrogen in addition to research perspectives.
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Affiliation(s)
- Tadakatsu Yoneyama
- Department of Applied Biological Chemistry, University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.
- National Agriculture and Food Research Organization, Kannondai 3-1-1, Tsukuba, Ibaraki 305-8666, Japan.
| | - Junko Terakado-Tonooka
- National Agriculture and Food Research Organization, Kannondai 3-1-1, Tsukuba, Ibaraki 305-8666, Japan.
| | - Zhihua Bao
- School of Ecology and Environment, Inner Mongolia University, 235 West University Blvd., Hohhot 010021, Inner Mongolia, China.
| | - Kiwamu Minamisawa
- Graduate School of Life Sciences, Tohoku University, Katahira, Aoba-ku, Sendai, Miyagi 980-8577, Japan.
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Mazumdar D, Saha SP, Ghosh S. Isolation, screening and application of a potent PGPR for enhancing growth of Chickpea as affected by nitrogen level. ACTA ACUST UNITED AC 2019. [DOI: 10.1080/19315260.2019.1632401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Deepika Mazumdar
- Department of Biotechnology, University of North Bengal, Siliguri, West Bengal, India
| | - Shyama Prasad Saha
- Department of Biotechnology, University of North Bengal, Siliguri, West Bengal, India
- Department of Microbiology, University of North Bengal, Siliguri, West Bengal, India
| | - Shilpi Ghosh
- Department of Biotechnology, University of North Bengal, Siliguri, West Bengal, India
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38
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Microbial associations enabling nitrogen acquisition in plants. Curr Opin Microbiol 2019; 49:83-89. [DOI: 10.1016/j.mib.2019.10.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 10/03/2019] [Accepted: 10/11/2019] [Indexed: 01/29/2023]
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Salgado MG, van Velzen R, Nguyen TV, Battenberg K, Berry AM, Lundin D, Pawlowski K. Comparative Analysis of the Nodule Transcriptomes of Ceanothus thyrsiflorus (Rhamnaceae, Rosales) and Datisca glomerata (Datiscaceae, Cucurbitales). FRONTIERS IN PLANT SCIENCE 2018; 9:1629. [PMID: 30487804 PMCID: PMC6246699 DOI: 10.3389/fpls.2018.01629] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 10/19/2018] [Indexed: 05/09/2023]
Abstract
Two types of nitrogen-fixing root nodule symbioses are known, rhizobial and actinorhizal symbioses. The latter involve plants of three orders, Fagales, Rosales, and Cucurbitales. To understand the diversity of plant symbiotic adaptation, we compared the nodule transcriptomes of Datisca glomerata (Datiscaceae, Cucurbitales) and Ceanothus thyrsiflorus (Rhamnaceae, Rosales); both species are nodulated by members of the uncultured Frankia clade, cluster II. The analysis focused on various features. In both species, the expression of orthologs of legume Nod factor receptor genes was elevated in nodules compared to roots. Since arginine has been postulated as export form of fixed nitrogen from symbiotic Frankia in nodules of D. glomerata, the question was whether the nitrogen metabolism was similar in nodules of C. thyrsiflorus. Analysis of the expression levels of key genes encoding enzymes involved in arginine metabolism revealed up-regulation of arginine catabolism, but no up-regulation of arginine biosynthesis, in nodules compared to roots of D. glomerata, while arginine degradation was not upregulated in nodules of C. thyrsiflorus. This new information corroborated an arginine-based metabolic exchange between host and microsymbiont for D. glomerata, but not for C. thyrsiflorus. Oxygen protection systems for nitrogenase differ dramatically between both species. Analysis of the antioxidant system suggested that the system in the nodules of D. glomerata leads to greater oxidative stress than the one in the nodules of C. thyrsiflorus, while no differences were found for the defense against nitrosative stress. However, induction of nitrite reductase in nodules of C. thyrsiflorus indicated that here, nitrite produced from nitric oxide had to be detoxified. Additional shared features were identified: genes encoding enzymes involved in thiamine biosynthesis were found to be upregulated in the nodules of both species. Orthologous nodule-specific subtilisin-like proteases that have been linked to the infection process in actinorhizal Fagales, were also upregulated in the nodules of D. glomerata and C. thyrsiflorus. Nodule-specific defensin genes known from actinorhizal Fagales and Cucurbitales, were also found in C. thyrsiflorus. In summary, the results underline the variability of nodule metabolism in different groups of symbiotic plants while pointing at conserved features involved in the infection process.
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Affiliation(s)
- Marco G. Salgado
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
| | - Robin van Velzen
- Laboratory of Molecular Biology, Department of Plant Sciences, Wageningen University, Wageningen, Netherlands
| | - Thanh Van Nguyen
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
| | - Kai Battenberg
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Alison M. Berry
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Daniel Lundin
- Centre for Ecology and Evolution in Microbial Model Systems, Linnaeus University, Kalmar, Sweden
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Katharina Pawlowski
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
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40
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Cooper B, Campbell KB, Beard HS, Garrett WM, Mowery J, Bauchan GR, Elia P. A Proteomic Network for Symbiotic Nitrogen Fixation Efficiency in Bradyrhizobium elkanii. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2018; 31:334-343. [PMID: 29117782 DOI: 10.1094/mpmi-10-17-0243-r] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Rhizobia colonize legumes and reduce N2 to NH3 in root nodules. The current model is that symbiotic rhizobia bacteroids avoid assimilating this NH3. Instead, host legume cells form glutamine from NH3, and the nitrogen is returned to the bacteroid as dicarboxylates, peptides, and amino acids. In soybean cells surrounding bacteroids, glutamine also is converted to ureides. One problem for soybean cultivation is inefficiency in symbiotic N2 fixation, the biochemical basis of which is unknown. Here, the proteomes of bacteroids of Bradyrhizobium elkanii USDA76 isolated from N2 fixation-efficient Peking and -inefficient Williams 82 soybean nodules were analyzed by mass spectrometry. Nearly half of the encoded bacterial proteins were quantified. Efficient bacteroids produced greater amounts of enzymes to form Nod factors and had increased amounts of signaling proteins, transporters, and enzymes needed to generate ATP to power nitrogenase and to acquire resources. Parallel investigation of nodule proteins revealed that Peking had no significantly greater accumulation of enzymes needed to assimilate NH3 than Williams 82. Instead, efficient bacteroids had increased amounts of enzymes to produce amino acids, including glutamine, and to form ureide precursors. These results support a model for efficient symbiotic N2 fixation in soybean where the bacteroid assimilates NH3 for itself.
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Affiliation(s)
- Bret Cooper
- 1 Soybean Genomics and Improvement Laboratory, USDA-ARS, Beltsville, MD 20705, U.S.A.; and
| | - Kimberly B Campbell
- 1 Soybean Genomics and Improvement Laboratory, USDA-ARS, Beltsville, MD 20705, U.S.A.; and
| | - Hunter S Beard
- 1 Soybean Genomics and Improvement Laboratory, USDA-ARS, Beltsville, MD 20705, U.S.A.; and
| | | | - Joseph Mowery
- 1 Soybean Genomics and Improvement Laboratory, USDA-ARS, Beltsville, MD 20705, U.S.A.; and
| | - Gary R Bauchan
- 1 Soybean Genomics and Improvement Laboratory, USDA-ARS, Beltsville, MD 20705, U.S.A.; and
| | - Patrick Elia
- 1 Soybean Genomics and Improvement Laboratory, USDA-ARS, Beltsville, MD 20705, U.S.A.; and
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Abstract
Rhizobia are some of the best-studied plant microbiota. These oligotrophic Alphaproteobacteria or Betaproteobacteria form symbioses with their legume hosts. Rhizobia must exist in soil and compete with other members of the microbiota before infecting legumes and forming N2-fixing bacteroids. These dramatic lifestyle and developmental changes are underpinned by large genomes and even more complex pan-genomes, which encompass the whole population and are subject to rapid genetic exchange. The ability to respond to plant signals and chemoattractants and to colonize nutrient-rich roots are crucial for the competitive success of these bacteria. The availability of a large body of genomic, physiological, biochemical and ecological studies makes rhizobia unique models for investigating community interactions and plant colonization.
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42
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Coba de la Peña T, Fedorova E, Pueyo JJ, Lucas MM. The Symbiosome: Legume and Rhizobia Co-evolution toward a Nitrogen-Fixing Organelle? FRONTIERS IN PLANT SCIENCE 2018; 8:2229. [PMID: 29403508 PMCID: PMC5786577 DOI: 10.3389/fpls.2017.02229] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 12/19/2017] [Indexed: 05/21/2023]
Abstract
In legume nodules, symbiosomes containing endosymbiotic rhizobial bacteria act as temporary plant organelles that are responsible for nitrogen fixation, these bacteria develop mutual metabolic dependence with the host legume. In most legumes, the rhizobia infect post-mitotic cells that have lost their ability to divide, although in some nodules cells do maintain their mitotic capacity after infection. Here, we review what is currently known about legume symbiosomes from an evolutionary and developmental perspective, and in the context of the different interactions between diazotroph bacteria and eukaryotes. As a result, it can be concluded that the symbiosome possesses organelle-like characteristics due to its metabolic behavior, the composite origin and differentiation of its membrane, the retargeting of host cell proteins, the control of microsymbiont proliferation and differentiation by the host legume, and the cytoskeletal dynamics and symbiosome segregation during the division of rhizobia-infected cells. Different degrees of symbiosome evolution can be defined, specifically in relation to rhizobial infection and to the different types of nodule. Thus, our current understanding of the symbiosome suggests that it might be considered a nitrogen-fixing link in organelle evolution and that the distinct types of legume symbiosomes could represent different evolutionary stages toward the generation of a nitrogen-fixing organelle.
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Affiliation(s)
- Teodoro Coba de la Peña
- Instituto de Ciencias Agrarias ICA-CSIC, Madrid, Spain
- Centro de Estudios Avanzados en Zonas Áridas (CEAZA), La Serena, Chile
| | - Elena Fedorova
- Instituto de Ciencias Agrarias ICA-CSIC, Madrid, Spain
- K. A. Timiryazev Institute of Plant Physiology, Russian Academy of Science, Moscow, Russia
| | - José J Pueyo
- Instituto de Ciencias Agrarias ICA-CSIC, Madrid, Spain
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López MF, Cabrera JJ, Salas A, Delgado MJ, López-García SL. Dissecting the role of NtrC and RpoN in the expression of assimilatory nitrate and nitrite reductases in Bradyrhizobium diazoefficiens. Antonie Van Leeuwenhoek 2017; 110:531-542. [PMID: 28040856 DOI: 10.1007/s10482-016-0821-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 12/19/2016] [Indexed: 11/28/2022]
Abstract
Bradyrhizobium diazoefficiens, a nitrogen-fixing endosymbiont of soybeans, is a model strain for studying rhizobial denitrification. This bacterium can also use nitrate as the sole nitrogen (N) source during aerobic growth by inducing an assimilatory nitrate reductase encoded by nasC located within the narK-bjgb-flp-nasC operon along with a nitrite reductase encoded by nirA at a different chromosomal locus. The global nitrogen two-component regulatory system NtrBC has been reported to coordinate the expression of key enzymes in nitrogen metabolism in several bacteria. In this study, we demonstrate that disruption of ntrC caused a growth defect in B. diazoefficiens cells in the presence of nitrate or nitrite as the sole N source and a decreased activity of the nitrate and nitrite reductase enzymes. Furthermore, the expression of narK-lacZ or nirA-lacZ transcriptional fusions was significantly reduced in the ntrC mutant after incubation under nitrate assimilation conditions. A B. diazoefficiens rpoN 1/2 mutant, lacking both copies of the gene encoding the alternative sigma factor σ54, was also defective in aerobic growth with nitrate as the N source as well as in nitrate and nitrite reductase expression. These results demonstrate that the NtrC regulator is required for expression of the B. diazoefficiens nasC and nirA genes and that the sigma factor RpoN is also involved in this regulation.
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Affiliation(s)
- María F López
- Instituto de Biotecnología y Biología Molecular (IBBM), Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata y CCT La Plata-CONICET, Calles 47 y 115, B1900AJL, La Plata, Argentina
| | - Juan J Cabrera
- Estación Experimental del Zaidín, CSIC, PO Box 419, 18080, Granada, Spain
| | - Ana Salas
- Estación Experimental del Zaidín, CSIC, PO Box 419, 18080, Granada, Spain
| | - María J Delgado
- Estación Experimental del Zaidín, CSIC, PO Box 419, 18080, Granada, Spain.
| | - Silvina L López-García
- Instituto de Biotecnología y Biología Molecular (IBBM), Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata y CCT La Plata-CONICET, Calles 47 y 115, B1900AJL, La Plata, Argentina.
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Imada EL, Rolla dos Santos AADP, Oliveira ALMD, Hungria M, Rodrigues EP. Indole-3-acetic acid production via the indole-3-pyruvate pathway by plant growth promoter Rhizobium tropici CIAT 899 is strongly inhibited by ammonium. Res Microbiol 2017; 168:283-292. [DOI: 10.1016/j.resmic.2016.10.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2016] [Revised: 10/26/2016] [Accepted: 10/31/2016] [Indexed: 11/26/2022]
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Estendorfer J, Stempfhuber B, Haury P, Vestergaard G, Rillig MC, Joshi J, Schröder P, Schloter M. The Influence of Land Use Intensity on the Plant-Associated Microbiome of Dactylis glomerata L. FRONTIERS IN PLANT SCIENCE 2017; 8:930. [PMID: 28680426 PMCID: PMC5478725 DOI: 10.3389/fpls.2017.00930] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 05/18/2017] [Indexed: 05/07/2023]
Abstract
In this study, we investigated the impact of different land use intensities (LUI) on the root-associated microbiome of Dactylis glomerata (orchardgrass). For this purpose, eight sampling sites with different land use intensity levels but comparable soil properties were selected in the southwest of Germany. Experimental plots covered land use levels from natural grassland up to intensively managed meadows. We used 16S rRNA gene based barcoding to assess the plant-associated community structure in the endosphere, rhizosphere and bulk soil of D. glomerata. Samples were taken at the reproductive stage of the plant in early summer. Our data indicated that roots harbor a distinct bacterial community, which clearly differed from the microbiome of the rhizosphere and bulk soil. Our results revealed Pseudomonadaceae, Enterobacteriaceae and Comamonadaceae as the most abundant endophytes independently of land use intensity. Rhizosphere and bulk soil were dominated also by Proteobacteria, but the most abundant families differed from those obtained from root samples. In the soil, the effect of land use intensity was more pronounced compared to root endophytes leading to a clearly distinct pattern of bacterial communities under different LUI from rhizosphere and bulk soil vs. endophytes. Overall, a change of community structure on the plant-soil interface was observed, as the number of shared OTUs between all three compartments investigated increased with decreasing land use intensity. Thus, our findings suggest a stronger interaction of the plant with its surrounding soil under low land use intensity. Furthermore, the amount and quality of available nitrogen was identified as a major driver for shifts in the microbiome structure in all compartments.
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Affiliation(s)
- Jennifer Estendorfer
- Research Unit Comparative Microbiome Analysis, Helmholtz Zentrum MünchenNeuherberg, Germany
| | - Barbara Stempfhuber
- Research Unit Comparative Microbiome Analysis, Helmholtz Zentrum MünchenNeuherberg, Germany
| | - Paula Haury
- Research Unit Comparative Microbiome Analysis, Helmholtz Zentrum MünchenNeuherberg, Germany
| | - Gisle Vestergaard
- Research Unit Comparative Microbiome Analysis, Helmholtz Zentrum MünchenNeuherberg, Germany
| | | | - Jasmin Joshi
- Biodiversity Research/Systematic Botany, Institute for Biochemistry und Biology, University of PotsdamPotsdam, Germany
| | - Peter Schröder
- Research Unit Comparative Microbiome Analysis, Helmholtz Zentrum MünchenNeuherberg, Germany
- *Correspondence: Peter Schröder,
| | - Michael Schloter
- Research Unit Comparative Microbiome Analysis, Helmholtz Zentrum MünchenNeuherberg, Germany
- Chair of Soil Science, Technical University of MunichFreising, Germany
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Terpolilli JJ, Masakapalli SK, Karunakaran R, Webb IUC, Green R, Watmough NJ, Kruger NJ, Ratcliffe RG, Poole PS. Lipogenesis and Redox Balance in Nitrogen-Fixing Pea Bacteroids. J Bacteriol 2016; 198:2864-75. [PMID: 27501983 PMCID: PMC5038014 DOI: 10.1128/jb.00451-16] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 07/26/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Within legume root nodules, rhizobia differentiate into bacteroids that oxidize host-derived dicarboxylic acids, which is assumed to occur via the tricarboxylic acid (TCA) cycle to generate NAD(P)H for reduction of N2 Metabolic flux analysis of laboratory-grown Rhizobium leguminosarum showed that the flux from [(13)C]succinate was consistent with respiration of an obligate aerobe growing on a TCA cycle intermediate as the sole carbon source. However, the instability of fragile pea bacteroids prevented their steady-state labeling under N2-fixing conditions. Therefore, comparative metabolomic profiling was used to compare free-living R. leguminosarum with pea bacteroids. While the TCA cycle was shown to be essential for maximal rates of N2 fixation, levels of pyruvate (5.5-fold reduced), acetyl coenzyme A (acetyl-CoA; 50-fold reduced), free coenzyme A (33-fold reduced), and citrate (4.5-fold reduced) were much lower in bacteroids. Instead of completely oxidizing acetyl-CoA, pea bacteroids channel it into both lipid and the lipid-like polymer poly-β-hydroxybutyrate (PHB), the latter via a type III PHB synthase that is active only in bacteroids. Lipogenesis may be a fundamental requirement of the redox poise of electron donation to N2 in all legume nodules. Direct reduction by NAD(P)H of the likely electron donors for nitrogenase, such as ferredoxin, is inconsistent with their redox potentials. Instead, bacteroids must balance the production of NAD(P)H from oxidation of acetyl-CoA in the TCA cycle with its storage in PHB and lipids. IMPORTANCE Biological nitrogen fixation by symbiotic bacteria (rhizobia) in legume root nodules is an energy-expensive process. Within legume root nodules, rhizobia differentiate into bacteroids that oxidize host-derived dicarboxylic acids, which is assumed to occur via the TCA cycle to generate NAD(P)H for reduction of N2 However, direct reduction of the likely electron donors for nitrogenase, such as ferredoxin, is inconsistent with their redox potentials. Instead, bacteroids must balance oxidation of plant-derived dicarboxylates in the TCA cycle with lipid synthesis. Pea bacteroids channel acetyl-CoA into both lipid and the lipid-like polymer poly-β-hydroxybutyrate, the latter via a type II PHB synthase. Lipogenesis is likely to be a fundamental requirement of the redox poise of electron donation to N2 in all legume nodules.
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Affiliation(s)
- Jason J Terpolilli
- Centre for Rhizobium Studies, Murdoch University, Perth, Australia Department of Molecular Microbiology, John Innes Centre, Norwich, United Kingdom
| | | | | | - Isabel U C Webb
- Department of Molecular Microbiology, John Innes Centre, Norwich, United Kingdom Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
| | - Rob Green
- Department of Molecular Microbiology, John Innes Centre, Norwich, United Kingdom
| | - Nicholas J Watmough
- Centre for Molecular Structure and Biochemistry, University of East Anglia, Norwich, United Kingdom
| | - Nicholas J Kruger
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
| | - R George Ratcliffe
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
| | - Philip S Poole
- Department of Molecular Microbiology, John Innes Centre, Norwich, United Kingdom Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
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47
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Mus F, Crook MB, Garcia K, Garcia Costas A, Geddes BA, Kouri ED, Paramasivan P, Ryu MH, Oldroyd GED, Poole PS, Udvardi MK, Voigt CA, Ané JM, Peters JW. Symbiotic Nitrogen Fixation and the Challenges to Its Extension to Nonlegumes. Appl Environ Microbiol 2016. [PMID: 27084023 DOI: 10.1128/aem.01055-01016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2023] Open
Abstract
Access to fixed or available forms of nitrogen limits the productivity of crop plants and thus food production. Nitrogenous fertilizer production currently represents a significant expense for the efficient growth of various crops in the developed world. There are significant potential gains to be had from reducing dependence on nitrogenous fertilizers in agriculture in the developed world and in developing countries, and there is significant interest in research on biological nitrogen fixation and prospects for increasing its importance in an agricultural setting. Biological nitrogen fixation is the conversion of atmospheric N2 to NH3, a form that can be used by plants. However, the process is restricted to bacteria and archaea and does not occur in eukaryotes. Symbiotic nitrogen fixation is part of a mutualistic relationship in which plants provide a niche and fixed carbon to bacteria in exchange for fixed nitrogen. This process is restricted mainly to legumes in agricultural systems, and there is considerable interest in exploring whether similar symbioses can be developed in nonlegumes, which produce the bulk of human food. We are at a juncture at which the fundamental understanding of biological nitrogen fixation has matured to a level that we can think about engineering symbiotic relationships using synthetic biology approaches. This minireview highlights the fundamental advances in our understanding of biological nitrogen fixation in the context of a blueprint for expanding symbiotic nitrogen fixation to a greater diversity of crop plants through synthetic biology.
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Affiliation(s)
- Florence Mus
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA
| | - Matthew B Crook
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Kevin Garcia
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Amaya Garcia Costas
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA
| | - Barney A Geddes
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
| | - Evangelia D Kouri
- Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma, USA
| | | | - Min-Hyung Ryu
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | | | - Philip S Poole
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
| | - Michael K Udvardi
- Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma, USA
| | - Christopher A Voigt
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Jean-Michel Ané
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - John W Peters
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA
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48
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Mus F, Crook MB, Garcia K, Garcia Costas A, Geddes BA, Kouri ED, Paramasivan P, Ryu MH, Oldroyd GED, Poole PS, Udvardi MK, Voigt CA, Ané JM, Peters JW. Symbiotic Nitrogen Fixation and the Challenges to Its Extension to Nonlegumes. Appl Environ Microbiol 2016; 82:3698-3710. [PMID: 27084023 PMCID: PMC4907175 DOI: 10.1128/aem.01055-16] [Citation(s) in RCA: 218] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Access to fixed or available forms of nitrogen limits the productivity of crop plants and thus food production. Nitrogenous fertilizer production currently represents a significant expense for the efficient growth of various crops in the developed world. There are significant potential gains to be had from reducing dependence on nitrogenous fertilizers in agriculture in the developed world and in developing countries, and there is significant interest in research on biological nitrogen fixation and prospects for increasing its importance in an agricultural setting. Biological nitrogen fixation is the conversion of atmospheric N2 to NH3, a form that can be used by plants. However, the process is restricted to bacteria and archaea and does not occur in eukaryotes. Symbiotic nitrogen fixation is part of a mutualistic relationship in which plants provide a niche and fixed carbon to bacteria in exchange for fixed nitrogen. This process is restricted mainly to legumes in agricultural systems, and there is considerable interest in exploring whether similar symbioses can be developed in nonlegumes, which produce the bulk of human food. We are at a juncture at which the fundamental understanding of biological nitrogen fixation has matured to a level that we can think about engineering symbiotic relationships using synthetic biology approaches. This minireview highlights the fundamental advances in our understanding of biological nitrogen fixation in the context of a blueprint for expanding symbiotic nitrogen fixation to a greater diversity of crop plants through synthetic biology.
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Affiliation(s)
- Florence Mus
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA
| | - Matthew B Crook
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Kevin Garcia
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Amaya Garcia Costas
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA
| | - Barney A Geddes
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
| | - Evangelia D Kouri
- Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma, USA
| | | | - Min-Hyung Ryu
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | | | - Philip S Poole
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
| | - Michael K Udvardi
- Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma, USA
| | - Christopher A Voigt
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Jean-Michel Ané
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - John W Peters
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA
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49
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Li YZ, Wang D, Feng XY, Jiao J, Chen WX, Tian CF. Genetic Analysis Reveals the Essential Role of Nitrogen Phosphotransferase System Components in Sinorhizobium fredii CCBAU 45436 Symbioses with Soybean and Pigeonpea Plants. Appl Environ Microbiol 2016; 82:1305-15. [PMID: 26682851 PMCID: PMC4751829 DOI: 10.1128/aem.03454-15] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 12/10/2015] [Indexed: 11/20/2022] Open
Abstract
The nitrogen phosphotransferase system (PTS(Ntr)) consists of EI(Ntr), NPr, and EIIA(Ntr). The active phosphate moiety derived from phosphoenolpyruvate is transferred through EI(Ntr) and NPr to EIIA(Ntr). Sinorhizobium fredii can establish a nitrogen-fixing symbiosis with the legume crops soybean (as determinate nodules) and pigeonpea (as indeterminate nodules). In this study, S. fredii strains with mutations in ptsP and ptsO (encoding EI(Ntr) and NPr, respectively) formed ineffective nodules on soybeans, while a strain with a ptsN mutation (encoding EIIA(Ntr)) was not defective in symbiosis with soybeans. Notable reductions in the numbers of bacteroids within each symbiosome and of poly-β-hydroxybutyrate granules in bacteroids were observed in nodules infected by the ptsP or ptsO mutant strains but not in those infected with the ptsN mutant strain. However, these defects of the ptsP and ptsO mutant strains were recovered in ptsP ptsN and ptsO ptsN double-mutant strains, implying a negative role of unphosphorylated EIIA(Ntr) in symbiosis. Moreover, the symbiotic defect of the ptsP mutant was also recovered by expressing EI(Ntr) with or without the GAF domain, indicating that the putative glutamine-sensing domain GAF is dispensable in symbiotic interactions. The critical role of PTS(Ntr) in symbiosis was also observed when related PTS(Ntr) mutant strains of S. fredii were inoculated on pigeonpea plants. Furthermore, nodule occupancy and carbon utilization tests suggested that multiple outputs could be derived from components of PTS(Ntr) in addition to the negative role of unphosphorylated EIIA(Ntr).
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Affiliation(s)
- Yue Zhen Li
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, and Rhizobium Research Center, China Agricultural University, Beijing, ChinaUniversity of Wisconsin-Madison
| | - Dan Wang
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, and Rhizobium Research Center, China Agricultural University, Beijing, ChinaUniversity of Wisconsin-Madison
| | - Xue Ying Feng
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, and Rhizobium Research Center, China Agricultural University, Beijing, ChinaUniversity of Wisconsin-Madison
| | - Jian Jiao
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, and Rhizobium Research Center, China Agricultural University, Beijing, ChinaUniversity of Wisconsin-Madison
| | - Wen Xin Chen
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, and Rhizobium Research Center, China Agricultural University, Beijing, ChinaUniversity of Wisconsin-Madison
| | - Chang Fu Tian
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, and Rhizobium Research Center, China Agricultural University, Beijing, ChinaUniversity of Wisconsin-Madison
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50
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Nambu M, Tatsukami Y, Morisaka H, Kuroda K, Ueda M. Quantitative time-course proteome analysis of Mesorhizobium loti during nodule maturation. J Proteomics 2015; 125:112-20. [DOI: 10.1016/j.jprot.2015.04.034] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 04/22/2015] [Accepted: 04/27/2015] [Indexed: 11/30/2022]
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