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Atika M, Leila B, Pereira SIA, Castro PML, Ali B. Enhancing Native Plant Establishment in Mine Tailings under Drought Stress Conditions through the Application of Organo-Mineral Amendments and Microbial Inoculants. PLANTS (BASEL, SWITZERLAND) 2024; 13:863. [PMID: 38592869 PMCID: PMC10975093 DOI: 10.3390/plants13060863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Revised: 03/07/2024] [Accepted: 03/15/2024] [Indexed: 04/11/2024]
Abstract
The implementation of phytoremediation strategies under arid and semiarid climates requires the use of appropriate plant species capable of withstanding multiple abiotic stresses. In this study, we assessed the combined effects of organo-mineral amendments and microbial inoculants on the chemical and biological properties of mine tailings, as well as on the growth of native plant species under drought stress conditions. Plants were cultivated in pots containing 1 kg of a mixture of mine tailings and topsoil (i.e., pre-mined superficial soil) in a 60:40 ratio, 6% marble sludge, and 10% sheep manure. Moreover, a consortium of four drought-resistant plant growth-promoting rhizobacteria (PGPR) was inoculated. Three irrigation levels were applied: well-watered, moderate water deficit, and severe water deficit, corresponding to 80%, 45%, and 30% of field capacity, respectively. The addition of topsoil and organo-mineral amendments to mine tailings significantly improved their chemical and biological properties, which were further enhanced by bacterial inoculation and plants' establishment. Water stress negatively impacted enzymatic activities in amended tailings, resulting in a significant decrease in acid and alkaline phosphatases, urease, and dehydrogenase activities. Similar results were obtained for bacteria, fungi, and actinomycete abundance. PGPR inoculation positively influenced the availability of phosphorus, total nitrogen, and organic carbon, while it increased alkaline phosphatase, urease (by about 10%), and dehydrogenase activity (by 50%). The rhizosphere of Peganum harmala showed the highest enzymatic activity and number of culturable microorganisms, especially in inoculated treatments. Severe water deficit negatively affected plant growth, leading to a 40% reduction in the shoot biomass of both Atriplex halimus and Pennisetum setaceum compared to well-watered plants. P. harmala showed greater tolerance to water stress, evidenced by lower decreases observed in root and shoot length and dry weight compared to well-watered plants. The use of bioinoculants mitigated the negative effects of drought on P. harmala shoot biomass, resulting in an increase of up to 75% in the aerial biomass in plants exposed to severe water deficit. In conclusion, the results suggest that the combination of organo-mineral amendments, PGPR inoculation, and P. harmala represents a promising approach to enhance the phytoremediation of metal-polluted soils under semiarid conditions.
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Affiliation(s)
- Madline Atika
- Laboratoire Bioressources et Sécurité Sanitaire des Aliments, Faculté des Sciences et Techniques, Université Cadi Ayyad, BP 549, Guéliz, Marrakech 40000, Morocco;
| | - Benidire Leila
- Laboratoire Bioressources et Sécurité Sanitaire des Aliments, Faculté des Sciences et Techniques, Université Cadi Ayyad, BP 549, Guéliz, Marrakech 40000, Morocco;
- Ecole Supérieure de Technologie El Kelâa des Sraghna, Université Cadi Ayyad, Route de Béni Mellal Km 8 B.P 104, El Kelaa des Sraghna 43000, Morocco
| | - Sofia I. A. Pereira
- CBQF—Centro de Biotecnologia e Química Fina, Laboratório Associado, Escola Superior de Biotecnologia, Universidade Católica Portuguesa, Rua Diogo Botelho 1327, 4169-005 Porto, Portugal; (S.I.A.P.); (P.M.L.C.)
| | - Paula M. L. Castro
- CBQF—Centro de Biotecnologia e Química Fina, Laboratório Associado, Escola Superior de Biotecnologia, Universidade Católica Portuguesa, Rua Diogo Botelho 1327, 4169-005 Porto, Portugal; (S.I.A.P.); (P.M.L.C.)
| | - Boularbah Ali
- Laboratoire Bioressources et Sécurité Sanitaire des Aliments, Faculté des Sciences et Techniques, Université Cadi Ayyad, BP 549, Guéliz, Marrakech 40000, Morocco;
- Center of Excellence for Soil and Africa Research in Africa, College of Agriculture and Environmental Sciences, Université Mohammed VI Polytechnique (UM6P), Benguerir 43150, Morocco
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Alahmad A, Harir M, Fochesato S, Tulumello J, Walker A, Barakat M, Ndour PMS, Schmitt-Kopplin P, Cournac L, Laplaze L, Heulin T, Achouak W. Unraveling the interplay between root exudates, microbiota, and rhizosheath formation in pearl millet. MICROBIOME 2024; 12:1. [PMID: 38167150 PMCID: PMC10763007 DOI: 10.1186/s40168-023-01727-3] [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: 08/09/2023] [Accepted: 11/19/2023] [Indexed: 01/05/2024]
Abstract
BACKGROUND The rhizosheath, a cohesive soil layer firmly adhering to plant roots, plays a vital role in facilitating water and mineral uptake. In pearl millet, rhizosheath formation is genetically controlled and influenced by root exudates. Here, we investigated the impact of root exudates on the microbiota composition, interactions, and assembly processes, and rhizosheath structure in pearl millet using four distinct lines with contrasting soil aggregation abilities. RESULTS Utilizing 16S rRNA gene and ITS metabarcoding for microbiota profiling, coupled with FTICR-MS metabonomic analysis of metabolite composition in distinct plant compartments and root exudates, we revealed substantial disparities in microbial diversity and interaction networks. The ß-NTI analysis highlighted bacterial rhizosphere turnover driven primarily by deterministic processes, showcasing prevalent homogeneous selection in root tissue (RT) and root-adhering soil (RAS). Conversely, fungal communities were more influenced by stochastic processes. In bulk soil assembly, a combination of deterministic and stochastic mechanisms shapes composition, with deterministic factors exerting a more pronounced role. Metabolic profiles across shoots, RT, and RAS in different pearl millet lines mirrored their soil aggregation levels, emphasizing the impact of inherent plant traits on microbiota composition and unique metabolic profiles in RT and exudates. Notably, exclusive presence of antimicrobial compounds, including DIMBOA and H-DIMBOA, emerged in root exudates and RT of low aggregation lines. CONCLUSIONS This research underscores the pivotal influence of root exudates in shaping the root-associated microbiota composition across pearl millet lines, entwined with their soil aggregation capacities. These findings underscore the interconnectedness of root exudates and microbiota, which jointly shape rhizosheath structure, deepening insights into soil-plant-microbe interactions and ecological processes shaping rhizosphere microbial communities. Deciphering plant-microbe interactions and their contribution to soil aggregation and microbiota dynamics holds promise for the advancement of sustainable agricultural strategies. Video Abstract.
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Affiliation(s)
- Abdelrahman Alahmad
- CEA, CNRS, BIAM, Lab Microbial Ecology of the Rhizosphere (LEMiRE), Aix Marseille Univ, 13108, Saint-Paul-Lez-Durance, France
- UniLaSalle, SFR NORVEGE FED 4277, AGHYLE Rouen UP 2018.C101, 3 Rue du Tronquet, 76130, Mont-Saint- Aignan, France
| | - Mourad Harir
- Research Unit Analytical BioGeoChemistry, Helmholtz Munich, Ingolstaedter Landstrasse 1, 85764, Neuherberg, Germany
- Chair Analytl Food Chem, Technical University of Munich, 85354, Freising, Weihenstephan, Germany
| | - Sylvain Fochesato
- CEA, CNRS, BIAM, Lab Microbial Ecology of the Rhizosphere (LEMiRE), Aix Marseille Univ, 13108, Saint-Paul-Lez-Durance, France
| | - Joris Tulumello
- CEA, CNRS, BIAM, Lab Microbial Ecology of the Rhizosphere (LEMiRE), Aix Marseille Univ, 13108, Saint-Paul-Lez-Durance, France
| | - Alesia Walker
- Research Unit Analytical BioGeoChemistry, Helmholtz Munich, Ingolstaedter Landstrasse 1, 85764, Neuherberg, Germany
| | - Mohamed Barakat
- CEA, CNRS, BIAM, Lab Microbial Ecology of the Rhizosphere (LEMiRE), Aix Marseille Univ, 13108, Saint-Paul-Lez-Durance, France
| | - Papa Mamadou Sitor Ndour
- CIRAD, INRAE, Eco&Sols, Université de Montpellier, Institut Agro, IRD FR, Montpellier, France
- UCEIV-ULCO, 50 Rue Ferdinand Buisson, 62228, Calais, France
- LMI IESOL, Centre de Recherche, ISRA-IRD de Bel Air, Dakar, Senegal
| | - Philippe Schmitt-Kopplin
- Research Unit Analytical BioGeoChemistry, Helmholtz Munich, Ingolstaedter Landstrasse 1, 85764, Neuherberg, Germany
- Chair Analytl Food Chem, Technical University of Munich, 85354, Freising, Weihenstephan, Germany
| | - Laurent Cournac
- CIRAD, INRAE, Eco&Sols, Université de Montpellier, Institut Agro, IRD FR, Montpellier, France
- LMI IESOL, Centre de Recherche, ISRA-IRD de Bel Air, Dakar, Senegal
| | - Laurent Laplaze
- UMR DIADE, Université de Montpellier, IRD, CIRAD, Montpellier, France
- LMI LAPSE, Centre de Recherche, ISRA-IRD de Bel Air, Dakar, Senegal
| | - Thierry Heulin
- CEA, CNRS, BIAM, Lab Microbial Ecology of the Rhizosphere (LEMiRE), Aix Marseille Univ, 13108, Saint-Paul-Lez-Durance, France.
| | - Wafa Achouak
- CEA, CNRS, BIAM, Lab Microbial Ecology of the Rhizosphere (LEMiRE), Aix Marseille Univ, 13108, Saint-Paul-Lez-Durance, France.
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Samokhin AS, Matyushin DD. How searching against multiple libraries can lead to biased results in GC/MS-based metabolomics. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2023; 37:e9437. [PMID: 36409456 DOI: 10.1002/rcm.9437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 11/15/2022] [Accepted: 11/17/2022] [Indexed: 06/16/2023]
Abstract
RATIONALE Databases of electron ionization mass spectra are often used in GC/MS-based untargeted metabolomics analysis. The results of the library search depend on several factors, such as the size and quality of the database, and the library search algorithm. We found out that the list of considered m/z values is another important parameter. Unfortunately, this information is not usually specified by software developers and it is hidden from the end user. METHODS We created synthetic data sets and figured out how several popular software products (AMDIS, ChromaTOF, MS Search, and Xcalibur) select the list of m/z values for the library search. Moreover, we considered data sets of real mass spectra (presented in both the NIST and FiehnLib libraries) and compared the library search results obtained within different software products. All programs under consideration use the NIST MS Search binaries to perform the library search using the Identity algorithm. RESULTS We found that AMDIS and ChromaTOF can give biased library search results under particular conditions. In untargeted metabolomics, this can happen when NIST and FiehnLib libraries are used simultaneously, the scan range of the instrument is less than 85, and the correct answer is present only in the FiehnLib library. CONCLUSIONS The main reason for biased results is that the information about the scan range is not stored in the metadata of library records. As a result, in the case of AMDIS and ChromaTOF software, some unrecorded peaks are considered as missing during the library search, the respective compound is penalized, and the correct answer falls outside the top five or even top 10 hits. At the same time, the default algorithm for selecting the list of considered m/z values implemented in MS Search is free from such unexpected behavior.
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Affiliation(s)
- Andrey S Samokhin
- Chemistry Department, Lomonosov Moscow State University, Moscow, Russia
| | - Dmitriy D Matyushin
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia
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Redha A, Al-Hasan R, Afzal M. Synergistic and concentration-dependent toxicity of multiple heavy metals compared with single heavy metals in Conocarpus lancifolius. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:23258-23272. [PMID: 33443733 PMCID: PMC8113142 DOI: 10.1007/s11356-020-12271-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 12/28/2020] [Indexed: 05/30/2023]
Abstract
While heavy metals (HMs) naturally occur in soil, anthropogenic activities can increase the level of these toxic elements. Conocarpus lancifolius Engl. (Combretaceae) was investigated as a potential phytoremediator of soils contaminated with HM containing crude oil. This study assessed the potential of C. lancifolius (CL), a locally available plant species in Kuwait, for resolving local issues of the HM-contaminated soils. The absorption, accumulation, and distribution of three toxic HMs (Cd, Ni, and Pb) and essential metals (Fe, Mg, and metalloid Se) were examined, and their role in plant toxicity and tolerance was evaluated. Conocarpus lancifolius plants were exposed to two different concentrations of single and mixed HMs for 30 days. The accumulation of HMs was determined in the roots, leaves, stems, and the soil using ICP/MS. Biomass, soil pH, proline and protein content, and bioaccumulation, extraction, and translocation factors were measured. The bioaccumulation, extraction, and transcription factors were all >1, indicating CC is a hyperaccumulator of HM. The HM accumulation in CL was concentration-dependent and depended on whether the plants were exposed to individual or mixed HMs. The C.C leaves, stems, and roots showed a significant accumulation of antioxidant constituents, such as proline, protein, Fe, Mg, and Se. There was an insignificant increase in the soil pH, and a decrease in plant biomass and a significant increase in protein, and osmoprotective-proline as a result of the interaction of mixed heavy metals that are more toxic than single heavy metals. This study indicates that C. lancifolius is a good candidate for phytoremediation of multiple HM-contaminated soils. Further studies to establish the phyto-physiological effect of multiple heavy metals are warranted.
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Affiliation(s)
- Amina Redha
- Department of Biological Studies, Faculty of Science, Kuwait University, Kuwait City, Kuwait
| | - Redha Al-Hasan
- Department of Biological Studies, Faculty of Science, Kuwait University, Kuwait City, Kuwait
| | - Mohammad Afzal
- Department of Biological Studies, Faculty of Science, Kuwait University, Kuwait City, Kuwait.
- , Gainesville, USA.
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Haskett TL, Tkacz A, Poole PS. Engineering rhizobacteria for sustainable agriculture. THE ISME JOURNAL 2021; 15:949-964. [PMID: 33230265 PMCID: PMC8114929 DOI: 10.1038/s41396-020-00835-4] [Citation(s) in RCA: 63] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 10/29/2020] [Accepted: 11/05/2020] [Indexed: 02/06/2023]
Abstract
Exploitation of plant growth promoting (PGP) rhizobacteria (PGPR) as crop inoculants could propel sustainable intensification of agriculture to feed our rapidly growing population. However, field performance of PGPR is typically inconsistent due to suboptimal rhizosphere colonisation and persistence in foreign soils, promiscuous host-specificity, and in some cases, the existence of undesirable genetic regulation that has evolved to repress PGP traits. While the genetics underlying these problems remain largely unresolved, molecular mechanisms of PGP have been elucidated in rigorous detail. Engineering and subsequent transfer of PGP traits into selected efficacious rhizobacterial isolates or entire bacterial rhizosphere communities now offers a powerful strategy to generate improved PGPR that are tailored for agricultural use. Through harnessing of synthetic plant-to-bacteria signalling, attempts are currently underway to establish exclusive coupling of plant-bacteria interactions in the field, which will be crucial to optimise efficacy and establish biocontainment of engineered PGPR. This review explores the many ecological and biotechnical facets of this research.
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Affiliation(s)
- Timothy L. Haskett
- grid.4991.50000 0004 1936 8948Department of Plant Sciences, University of Oxford, Oxford, OX1 3RB UK
| | - Andrzej Tkacz
- grid.4991.50000 0004 1936 8948Department of Plant Sciences, University of Oxford, Oxford, OX1 3RB UK
| | - Philip S. Poole
- grid.4991.50000 0004 1936 8948Department of Plant Sciences, University of Oxford, Oxford, OX1 3RB UK
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He Z, Deng Y, Xu M, Li J, Liang J, Xiong J, Yu H, Wu B, Wu L, Xue K, Shi S, Carrillo Y, Van Nostrand JD, Hobbie SE, Reich PB, Schadt CW, Kent AD, Pendall E, Wallenstein M, Luo Y, Yan Q, Zhou J. Microbial functional genes commonly respond to elevated carbon dioxide. ENVIRONMENT INTERNATIONAL 2020; 144:106068. [PMID: 32871382 DOI: 10.1016/j.envint.2020.106068] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 08/14/2020] [Accepted: 08/17/2020] [Indexed: 06/11/2023]
Abstract
Atmospheric CO2 concentration is increasing, largely due to anthropogenic activities. Previous studies of individual free-air CO2 enrichment (FACE) experimental sites have shown significant impacts of elevated CO2 (eCO2) on soil microbial communities; however, no common microbial response patterns have yet emerged, challenging our ability to predict ecosystem functioning and sustainability in the future eCO2 environment. Here we analyzed 66 soil microbial communities from five FACE sites, and showed common microbial response patterns to eCO2, especially for key functional genes involved in carbon and nitrogen fixation (e.g., pcc/acc for carbon fixation, nifH for nitrogen fixation), carbon decomposition (e.g., amyA and pulA for labile carbon decomposition, mnp and lcc for recalcitrant carbon decomposition), and greenhouse gas emissions (e.g., mcrA for methane production, norB for nitrous oxide production) across five FACE sites. Also, the relative abundance of those key genes was generally increased and directionally associated with increased biomass, soil carbon decomposition, and soil moisture. In addition, a further literature survey of more disparate FACE experimental sites indicated increased biomass, soil carbon decay, nitrogen fixation, methane and nitrous oxide emissions, plant and soil carbon and nitrogen under eCO2. A conceptual framework was developed to link commonly responsive functional genes with ecosystem processes, such as pcc/acc vs. soil carbon storage, amyA/pulA/mnp/lcc vs. soil carbon decomposition, and nifH vs. nitrogen availability, suggesting that such common responses of microbial functional genes may have the potential to predict ecosystem functioning and sustainability in the future eCO2 environment.
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Affiliation(s)
- Zhili He
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou 510006, China; Institute for Environmental Genomics, The University of Oklahoma, Norman, OK 73019, United States; Department of Microbiology and Plant Biology, The University of Oklahoma, Norman, OK 73019, United States; College of Agronomy, Hunan Agricultural University, Changsha 410128, China.
| | - Ye Deng
- Institute for Environmental Genomics, The University of Oklahoma, Norman, OK 73019, United States; Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Meiying Xu
- Institute for Environmental Genomics, The University of Oklahoma, Norman, OK 73019, United States; State Key Laboratory of Applied Microbiology Southern China, Guangdong Institute of Microbiology, Guangzhou 510070, China
| | - Juan Li
- Institute for Environmental Genomics, The University of Oklahoma, Norman, OK 73019, United States; College of Agronomy, Hunan Agricultural University, Changsha 410128, China
| | - Junyi Liang
- Department of Microbiology and Plant Biology, The University of Oklahoma, Norman, OK 73019, United States
| | - Jinbo Xiong
- Institute for Environmental Genomics, The University of Oklahoma, Norman, OK 73019, United States; School of Marine Sciences, Ningbo University, Ningbo 315211, China
| | - Hao Yu
- Institute for Environmental Genomics, The University of Oklahoma, Norman, OK 73019, United States; Harbin Institute of Technology, Harbin 150001, China; School of Environmental Science and Engineering, Liaoning Technical University, Fuxin 123000, China
| | - Bo Wu
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou 510006, China; Institute for Environmental Genomics, The University of Oklahoma, Norman, OK 73019, United States; Department of Microbiology and Plant Biology, The University of Oklahoma, Norman, OK 73019, United States
| | - Liyou Wu
- Institute for Environmental Genomics, The University of Oklahoma, Norman, OK 73019, United States; Department of Microbiology and Plant Biology, The University of Oklahoma, Norman, OK 73019, United States
| | - Kai Xue
- Institute for Environmental Genomics, The University of Oklahoma, Norman, OK 73019, United States; Department of Microbiology and Plant Biology, The University of Oklahoma, Norman, OK 73019, United States
| | - Shengjing Shi
- Institute for Environmental Genomics, The University of Oklahoma, Norman, OK 73019, United States; Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720, United States
| | - Yolima Carrillo
- Hawkesbury Institute for the Environment, University of Western Sydney, Sydney 2751, Australia; University of Wyoming, Laramie, WY 82071, United States
| | - Joy D Van Nostrand
- Institute for Environmental Genomics, The University of Oklahoma, Norman, OK 73019, United States; Department of Microbiology and Plant Biology, The University of Oklahoma, Norman, OK 73019, United States
| | - Sarah E Hobbie
- The University of Minnesota, St. Paul, MN 55108, United States
| | - Peter B Reich
- Hawkesbury Institute for the Environment, University of Western Sydney, Sydney 2751, Australia; The University of Minnesota, St. Paul, MN 55108, United States
| | - Christopher W Schadt
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States
| | - Angela D Kent
- Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States
| | - Elise Pendall
- Hawkesbury Institute for the Environment, University of Western Sydney, Sydney 2751, Australia; University of Wyoming, Laramie, WY 82071, United States
| | - Matthew Wallenstein
- Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO 80523, United States
| | - Yiqi Luo
- Department of Microbiology and Plant Biology, The University of Oklahoma, Norman, OK 73019, United States
| | - Qingyun Yan
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou 510006, China; Institute for Environmental Genomics, The University of Oklahoma, Norman, OK 73019, United States; Department of Microbiology and Plant Biology, The University of Oklahoma, Norman, OK 73019, United States.
| | - Jizhong Zhou
- Institute for Environmental Genomics, The University of Oklahoma, Norman, OK 73019, United States; Department of Microbiology and Plant Biology, The University of Oklahoma, Norman, OK 73019, United States; Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States; State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
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Kanbar HJ, Matar Z, Safa GAA, Kazpard V. Selective metal leaching from technosols based on synthetic root exudate composition. J Environ Sci (China) 2020; 96:85-92. [PMID: 32819702 DOI: 10.1016/j.jes.2020.04.040] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Revised: 04/13/2020] [Accepted: 04/24/2020] [Indexed: 06/11/2023]
Abstract
This study focused on metal release from technosols induced by synthetic root exudate (SRE). The effect of SRE composition on metal release was studied using six technosols. This was done by treating the technosols with SRE solutions having varying concentrations of low molecular weight organic acids (LMWOAs), namely oxalic, citric, and malic acids. Consequently, the physico-chemical parameters (pH and electric conductivity), Ca, Mg, Fe, Zn, and Cu release (by atomic absorption spectroscopy, AAS), chemical changes (by Fourier transform infrared, FT-IR), and organic parameters (by fluorescence) were investigated. Metal release showed to be dependent on the SRE composition and technosol characteristics. Citric acid selectively released Ca, Mg, Zn, and Cu from technosols in a concentration-dependent manner; oxalic acid showed a significant role in the release of Mg and Fe. Under relatively high LMWOA concentrations, particulate organo-mineral complexes precipitated. Additionally, technosol weathering was seen by the dissolution of humic substances and ferriallophanes, which in turn caused metal release. However, re-precipitation of these phases showed to re-sorb metals, thus underestimating the role of LMWOAs in metal release. Therefore, the selective metal leaching was highly dependent on the SRE composition and LMWOA concentrations on one hand, and on the mineral, organic, and organo-mineral components of the technosols on the other. The understanding of such processes is crucial for proposing and implementing environmental management strategies to reduce metal leaching or for the beneficial re-usage of metals (e.g., for agromining) from technosols.
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Affiliation(s)
- Hussein Jaafar Kanbar
- Research and Analysis Platform for Environmental Sciences (PRASE), Doctoral School of Sciences and Technology (EDST), The Lebanese University, P.O. 5, Rafic Hariri Campus, Hadat, Lebanon; Department of Chemistry, Umeå University, SE-901 87, Umeå, Sweden.
| | - Zeinab Matar
- Research and Analysis Platform for Environmental Sciences (PRASE), Doctoral School of Sciences and Technology (EDST), The Lebanese University, P.O. 5, Rafic Hariri Campus, Hadat, Lebanon; Department of Earth and Life Sciences, Faculty of Sciences, The Lebanese University, Rafic Hariri Campus, Hadat, Lebanon; Laboratory of Georesources, Geosciences and Environment (L2GE), Faculty of Sciences, The Lebanese University, Fanar, Lebanon.
| | - Ghina Abed-AlHadi Safa
- Research and Analysis Platform for Environmental Sciences (PRASE), Doctoral School of Sciences and Technology (EDST), The Lebanese University, P.O. 5, Rafic Hariri Campus, Hadat, Lebanon; Department of Earth and Life Sciences, Faculty of Sciences, The Lebanese University, Rafic Hariri Campus, Hadat, Lebanon
| | - Veronique Kazpard
- Research and Analysis Platform for Environmental Sciences (PRASE), Doctoral School of Sciences and Technology (EDST), The Lebanese University, P.O. 5, Rafic Hariri Campus, Hadat, Lebanon; Department of Earth and Life Sciences, Faculty of Sciences, The Lebanese University, Rafic Hariri Campus, Hadat, Lebanon; Laboratory of Georesources, Geosciences and Environment (L2GE), Faculty of Sciences, The Lebanese University, Fanar, Lebanon
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Hazrati H, Fomsgaard IS, Kudsk P. Root-Exuded Benzoxazinoids: Uptake and Translocation in Neighboring Plants. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2020; 68:10609-10617. [PMID: 32877180 DOI: 10.1021/acs.jafc.0c04245] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Plants have evolved advanced chemical defense mechanisms, including root exudation, which enable them to respond to changes occurring in their surroundings rapidly. Yet, it remains unresolved how root exudation affects belowground plant-plant interactions. The objective of this study was to elucidate the fate of benzoxazinoids (BXs) exuded from the roots of rye (Secale cereale L.) plants grown with hairy vetch (Vicia villosa). A rapid method that allows nondestructive and reproducible chemical profiling of the root exudates was developed. Targeted chemical analysis with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was performed to investigate the changes in the composition and concentration of BXs in the rye plant, and its root exudate in response to cocultivation with hairy vetch. Furthermore, hairy vetch plants were screened for the possible uptake of BXs from the rhizosphere and their translocation to the shoot. Rye significantly increased the production and root exudation of BXs, in particular 2-β-d-glucopyranosyloxy-4-hydroxy-1,4-benzoxazin-3-one (DIBOA-glc) and 2-β-d-glucopyranosyloxy-4-hydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA-glc), in response to cocultivation with hairy vetch. DIBOA-glc and DIMBOA-glc were absorbed by the roots of the cocultivated hairy vetch plants and translocated to the shoots. These findings will strongly improve our understanding of the exudation of BXs from the rye plant and their role in interaction with other plant species.
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Affiliation(s)
- Hossein Hazrati
- Department of Agroecology, Aarhus University, 4200 Aarhus, Denmark
| | - Inge S Fomsgaard
- Department of Agroecology, Aarhus University, 4200 Aarhus, Denmark
| | - Per Kudsk
- Department of Agroecology, Aarhus University, 4200 Aarhus, Denmark
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Molina L, Segura A, Duque E, Ramos JL. The versatility of Pseudomonas putida in the rhizosphere environment. ADVANCES IN APPLIED MICROBIOLOGY 2019; 110:149-180. [PMID: 32386604 DOI: 10.1016/bs.aambs.2019.12.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
This article addresses the lifestyle of Pseudomonas and focuses on how Pseudomonas putida can be used as a model system for biotechnological processes in agriculture, and in the removal of pollutants from soils. In this chapter we aim to show how a deep analysis using genetic information and experimental tests has helped to reveal insights into the lifestyle of Pseudomonads. Pseudomonas putida is a Plant Growth Promoting Rhizobacteria (PGPR) that establishes commensal relationships with plants. The interaction involves a series of functions encoded by core genes which favor nutrient mobilization, prevention of pathogen development and efficient niche colonization. Certain Pseudomonas putida strains harbor accessory genes that confer specific biodegradative properties and because these microorganisms can thrive on the roots of plants they can be exploited to remove pollutants via rhizoremediation, making the consortium plant/Pseudomonas a useful tool to combat pollution.
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Affiliation(s)
- Lázaro Molina
- CSIC- Estación Experimental del Zaidín, Granada, Spain
| | - Ana Segura
- CSIC- Estación Experimental del Zaidín, Granada, Spain
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10
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Cox DE, Dyer S, Weir R, Cheseto X, Sturrock M, Coyne D, Torto B, Maule AG, Dalzell JJ. ABC transporter genes ABC-C6 and ABC-G33 alter plant-microbe-parasite interactions in the rhizosphere. Sci Rep 2019; 9:19899. [PMID: 31882903 PMCID: PMC6934816 DOI: 10.1038/s41598-019-56493-w] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 12/08/2019] [Indexed: 11/20/2022] Open
Abstract
Plants are master regulators of rhizosphere ecology, secreting a complex mixture of compounds into the soil, collectively termed plant root exudate. Root exudate composition is highly dynamic and functional, mediating economically important interactions between plants and a wide range of soil organisms. Currently we know very little about the molecular basis of root exudate composition, which is a key hurdle to functional exploitation of root exudates for crop improvement. Root expressed transporters modulate exudate composition and could be manipulated to develop beneficial plant root exudate traits. Using Virus Induced Gene silencing (VIGS), we demonstrate that knockdown of two root-expressed ABC transporter genes in tomato cv. Moneymaker, ABC-C6 and ABC-G33, alters the composition of semi-volatile compounds in collected root exudates. Root exudate chemotaxis assays demonstrate that knockdown of each transporter gene triggers the repulsion of economically relevant Meloidogyne and Globodera spp. plant parasitic nematodes, which are attracted to control treatment root exudates. Knockdown of ABC-C6 inhibits egg hatching of Meloidogyne and Globodera spp., relative to controls. Knockdown of ABC-G33 has no impact on egg hatching of Meloidogyne spp. but has a substantial inhibitory impact on egg hatching of G. pallida. ABC-C6 knockdown has no impact on the attraction of the plant pathogen Agrobacterium tumefaciens, or the plant growth promoting Bacillus subtilis, relative to controls. Silencing ABC-G33 induces a statistically significant reduction in attraction of B. subtilis, with no impact on attraction of A. tumefaciens. By inoculating selected differentially exuded compounds into control root exudates, we demonstrate that hexadecaonic acid and pentadecane are biologically relevant parasite repellents. ABC-C6 represents a promising target for breeding or biotechnology intervention strategies as gene knockdown leads to the repulsion of economically important plant parasites and retains attraction of the beneficial rhizobacterium B. subtilis. This study exposes the link between ABC transporters, root exudate composition, and ex planta interactions with agriculturally and economically relevant rhizosphere organisms, paving the way for new approaches to rhizosphere engineering and crop protection.
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Affiliation(s)
- Deborah Elizabeth Cox
- School of Biological Sciences, Institute for Global Food Security, Queen's University Belfast, Belfast, UK
| | - Steven Dyer
- School of Biological Sciences, Institute for Global Food Security, Queen's University Belfast, Belfast, UK
| | - Ryan Weir
- School of Biological Sciences, Institute for Global Food Security, Queen's University Belfast, Belfast, UK
| | - Xavier Cheseto
- The International Center of Insect Physiology and Ecology, Nairobi, Kenya
| | - Matthew Sturrock
- School of Biological Sciences, Institute for Global Food Security, Queen's University Belfast, Belfast, UK
| | - Danny Coyne
- The International Institute for Tropical Agriculture, Nairobi, Kenya
| | - Baldwyn Torto
- The International Center of Insect Physiology and Ecology, Nairobi, Kenya
| | - Aaron G Maule
- School of Biological Sciences, Institute for Global Food Security, Queen's University Belfast, Belfast, UK
| | - Johnathan J Dalzell
- School of Biological Sciences, Institute for Global Food Security, Queen's University Belfast, Belfast, UK.
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11
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Misra P, Maji D, Awasthi A, Pandey SS, Yadav A, Pandey A, Saikia D, Babu CSV, Kalra A. Vulnerability of Soil Microbiome to Monocropping of Medicinal and Aromatic Plants and Its Restoration Through Intercropping and Organic Amendments. Front Microbiol 2019; 10:2604. [PMID: 31803153 PMCID: PMC6877478 DOI: 10.3389/fmicb.2019.02604] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 10/28/2019] [Indexed: 12/22/2022] Open
Abstract
Cultivation of medicinal and aromatic plants (MAPs) is persistently increasing due to excessive demands of naturals. Agricultural land and its microbial diversity are primarily adapted to conventional crops, and introduction of MAP and their continuous monocropping may disturb the ecological stability of soil microbiome. Here, the effect of cultivation of MAPs on soil microbial diversity was studied. The aim of the study is to examine the effects of cultivation of MAPs on the possible shift in soil microbial diversity and to restore such impacts by using organic amendments or intercropping. Terminal restriction fragments polymorphism (TRFLP) and next-generation sequencing (NGS) studies showed that of the various selected MAPs, maximal modulation in the soil microbial diversity patterns was noticed in fields of Mentha arvensis and Artemisia annua, and the traces of essential oil/phytochemicals were detected in bulk and rhizospheric soil. In both Artemisia- and Mentha-cultivated soil, the total operating taxonomic unit (OTU) declined in both bulk and rhizospheric soil in comparison to control (Zea mays), but the bacterial richness of Mentha soil was slightly higher than that of control. However, cultivation of Mentha improved the evenness of the microbial community. The inclusion of crops like Sesbania and Chlorophytum and the application of vermicompost (VC) enhanced the microbial richness and evenness, thereby restoring the soil microbial state shift and resulting in higher productivity in the continuously Mentha cropped field. Our study concludes that long-term cultivation of some MAPs may affect the richness but promote the evenness of microbial diversity. The state shift could be restored to some extent, and crop productivity could be enhanced by the inclusion of selected crops and organic manures in cropping systems.
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Affiliation(s)
- Pooja Misra
- Microbial Technology Department, Central Institute of Medicinal and Aromatic Plants, Council of Scientific and Industrial Research, Lucknow, India
- Academy of Scientific and Innovative Research, Central Institute of Medicinal and Aromatic Plants, Council of Scientific and Industrial Research, Lucknow, India
| | - Deepamala Maji
- Microbial Technology Department, Central Institute of Medicinal and Aromatic Plants, Council of Scientific and Industrial Research, Lucknow, India
| | - Ashutosh Awasthi
- Microbial Technology Department, Central Institute of Medicinal and Aromatic Plants, Council of Scientific and Industrial Research, Lucknow, India
| | - Shiv Shanker Pandey
- Microbial Technology Department, Central Institute of Medicinal and Aromatic Plants, Council of Scientific and Industrial Research, Lucknow, India
| | - Anju Yadav
- Analytical Chemistry Department, Central Institute of Medicinal and Aromatic Plants, Council of Scientific and Industrial Research, Lucknow, India
| | - Alok Pandey
- Microbial Technology Department, Central Institute of Medicinal and Aromatic Plants, Council of Scientific and Industrial Research, Lucknow, India
| | - Dharmendra Saikia
- Department of Molecular Bioprospection, Council of Scientific and Industrial Research, Lucknow, India
| | - C. S. Vivek Babu
- Academy of Scientific and Innovative Research, Central Institute of Medicinal and Aromatic Plants, Council of Scientific and Industrial Research, Lucknow, India
- Central Institute of Medicinal and Aromatic Plants, Research Centre, Council of Scientific and Industrial Research, Bengaluru, India
| | - Alok Kalra
- Microbial Technology Department, Central Institute of Medicinal and Aromatic Plants, Council of Scientific and Industrial Research, Lucknow, India
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12
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Grunert O, Robles-Aguilar AA, Hernandez-Sanabria E, Schrey SD, Reheul D, Van Labeke MC, Vlaeminck SE, Vandekerckhove TGL, Mysara M, Monsieurs P, Temperton VM, Boon N, Jablonowski ND. Tomato plants rather than fertilizers drive microbial community structure in horticultural growing media. Sci Rep 2019; 9:9561. [PMID: 31266970 PMCID: PMC6606572 DOI: 10.1038/s41598-019-45290-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 06/04/2019] [Indexed: 11/09/2022] Open
Abstract
Synthetic fertilizer production is associated with a high environmental footprint, as compounds typically dissolve rapidly leaching emissions to the atmosphere or surface waters. We tested two recovered nutrients with slower release patterns, as promising alternatives for synthetic fertilizers: struvite and a commercially available organic fertilizer. Using these fertilizers as nitrogen source, we conducted a rhizotron experiment to test their effect on plant performance and nutrient recovery in juvenile tomato plants. Plant performance was significantly improved when organic fertilizer was provided, promoting higher shoot biomass. Since the microbial community influences plant nitrogen availability, we characterized the root-associated microbial community structure and functionality. Analyses revealed distinct root microbial community structure when different fertilizers were supplied. However, plant presence significantly increased the similarity of the microbial community over time, regardless of fertilization. Additionally, the presence of the plant significantly reduced the potential ammonia oxidation rates, implying a possible role of the rhizosheath microbiome or nitrification inhibition by the plant. Our results indicate that nitrifying community members are impacted by the type of fertilizer used, while tomato plants influenced the potential ammonia-oxidizing activity of nitrogen-related rhizospheric microbial communities. These novel insights on interactions between recovered fertilizers, plant and associated microbes can contribute to develop sustainable crop production systems.
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Affiliation(s)
- Oliver Grunert
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, 9000, Gent, Belgium.,Greenyard, Skaldenstraat 7a, 9042, Desteldonk, Belgium
| | - Ana A Robles-Aguilar
- Forschungszentrum Jülich GmbH, Institute of Bio- and Geosciences, IBG-2: Plant Sciences, 52428, Jülich, Germany.,Laboratory of Analytical Chemistry and Applied Ecochemistry, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000, Ghent, Belgium
| | - Emma Hernandez-Sanabria
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, 9000, Gent, Belgium
| | - Silvia D Schrey
- Forschungszentrum Jülich GmbH, Institute of Bio- and Geosciences, IBG-2: Plant Sciences, 52428, Jülich, Germany
| | - Dirk Reheul
- Department of Plant and Crops, Ghent University, Coupure Links 653, 9000, Gent, Belgium
| | | | - Siegfried E Vlaeminck
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, 9000, Gent, Belgium.,Research Group of Sustainable Energy, Air and Water Technology, Department of Bioscience Engineering, University of Antwerp, Groenenborgerlaan 171, 2020, Antwerpen, Belgium
| | - Tom G L Vandekerckhove
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, 9000, Gent, Belgium
| | - Mohamed Mysara
- Unit of Microbiology, Belgian Nuclear Research Center (SCK•CEN), Mol, Belgium.,Department of Bioscience Engineering, Vrije Universiteit Brussel, Brussels, Belgium
| | - Pieter Monsieurs
- Unit of Microbiology, Belgian Nuclear Research Center (SCK•CEN), Mol, Belgium.,Unit Health, Flemish Institute for Technological Research (VITO), Mol, Belgium
| | - Vicky M Temperton
- Institute of Ecology, Leuphana University Lüneburg, Universitätsallee 1, D-21335, Lüneburg, Germany
| | - Nico Boon
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, 9000, Gent, Belgium.
| | - Nicolai D Jablonowski
- Forschungszentrum Jülich GmbH, Institute of Bio- and Geosciences, IBG-2: Plant Sciences, 52428, Jülich, Germany.
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13
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Kawasaki A, Okada S, Zhang C, Delhaize E, Mathesius U, Richardson AE, Watt M, Gilliham M, Ryan PR. A sterile hydroponic system for characterising root exudates from specific root types and whole-root systems of large crop plants. PLANT METHODS 2018; 14:114. [PMID: 30598690 PMCID: PMC6300921 DOI: 10.1186/s13007-018-0380-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 12/10/2018] [Indexed: 05/19/2023]
Abstract
BACKGROUND Plant roots release a variety of organic compounds into the soil which alter the physical, chemical and biological properties of the rhizosphere. Root exudates are technically challenging to measure in soil because roots are difficult to access and exudates can be bound by minerals or consumed by microorganisms. Exudates are easier to measure with hydroponically-grown plants but, even here, simple compounds such as sugars and organic acids can be rapidly assimilated by microorganisms. Sterile hydroponic systems avoid this shortcoming but it is very difficult to maintain sterility for long periods especially for larger crop species. As a consequence, studies often use small model species such as Arabidopsis to measure exudates or use seedlings of crop plants which only have immature roots systems. RESULTS We developed a simple hydroponic system for cultivating large crop plants in sterile conditions for more than 30 days. Using this system wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) plants were grown in sterile conditions for 30 days by which time they had reached the six-leaf stage and developed mature root systems with seminal, nodal and lateral roots. To demonstrate the utility of this system we characterized the aluminium-activated exudation of malate from the major types of wheat roots for the first time. We found that all root types measured released malate but the amounts were two-fold greater from the seminal and nodal axile roots compared with the lateral roots. Additionally, we showed that this sterile growth system could be used to collect exudates from intact whole root systems of barley. CONCLUSIONS We developed a simple hydroponic system that enables cereal plants to be grown in sterile conditions for longer periods than previously recorded. Using this system we measured, for the first time, the aluminium-activated efflux of malate from the major types of wheat roots. We showed the system can also be used for collecting exudates from intact root systems of 30-day-old barley plants. This hydroponic system can be modified for various purposes. Importantly it enables the study of exudates from crop species with mature root systems.
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Affiliation(s)
| | - Shoko Okada
- CSIRO Land and Water, Canberra, ACT Australia
| | - Chunyan Zhang
- CSIRO Agriculture and Food, Canberra, ACT Australia
- Present Address: College of Life Science, China West Normal University, Nanchong, Sichuan China
| | | | - Ulrike Mathesius
- Division of Plant Science, Research School of Biology, Australian National University, Canberra, ACT Australia
| | | | | | - Matthew Gilliham
- ARC Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, Waite Research Institute, University of Adelaide, Glen Osmond, SA Australia
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14
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White JF, Kingsley KL, Verma SK, Kowalski KP. Rhizophagy Cycle: An Oxidative Process in Plants for Nutrient Extraction from Symbiotic Microbes. Microorganisms 2018; 6:microorganisms6030095. [PMID: 30227634 PMCID: PMC6164190 DOI: 10.3390/microorganisms6030095] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Revised: 09/01/2018] [Accepted: 09/05/2018] [Indexed: 12/20/2022] Open
Abstract
In this paper, we describe a mechanism for the transfer of nutrients from symbiotic microbes (bacteria and fungi) to host plant roots that we term the ‘rhizophagy cycle.’ In the rhizophagy cycle, microbes alternate between a root intracellular endophytic phase and a free-living soil phase. Microbes acquire soil nutrients in the free-living soil phase; nutrients are extracted through exposure to host-produced reactive oxygen in the intracellular endophytic phase. We conducted experiments on several seed-vectored microbes in several host species. We found that initially the symbiotic microbes grow on the rhizoplane in the exudate zone adjacent the root meristem. Microbes enter root tip meristem cells—locating within the periplasmic spaces between cell wall and plasma membrane. In the periplasmic spaces of root cells, microbes convert to wall-less protoplast forms. As root cells mature, microbes continue to be subjected to reactive oxygen (superoxide) produced by NADPH oxidases (NOX) on the root cell plasma membranes. Reactive oxygen degrades some of the intracellular microbes, also likely inducing electrolyte leakage from microbes—effectively extracting nutrients from microbes. Surviving bacteria in root epidermal cells trigger root hair elongation and as hairs elongate bacteria exit at the hair tips, reforming cell walls and cell shapes as microbes emerge into the rhizosphere where they may obtain additional nutrients. Precisely what nutrients are transferred through rhizophagy or how important this process is for nutrient acquisition is still unknown.
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Affiliation(s)
- James F White
- Department of Plant Biology, Rutgers University, New Brunswick, NJ 08901, USA.
| | - Kathryn L Kingsley
- Department of Plant Biology, Rutgers University, New Brunswick, NJ 08901, USA.
| | - Satish K Verma
- Centre of Advanced Study in Botany, Banaras Hindu University, Varanasi, UP 221005, India.
| | - Kurt P Kowalski
- U.S. Geological Survey, Great Lakes Science Center, 1451 Green Road, Ann Arbor, MI 48105-2807, USA.
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15
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Edayilam N, Montgomery D, Ferguson B, Maroli AS, Martinez N, Powell BA, Tharayil N. Phosphorus Stress-Induced Changes in Plant Root Exudation Could Potentially Facilitate Uranium Mobilization from Stable Mineral Forms. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:7652-7662. [PMID: 29722538 DOI: 10.1021/acs.est.7b05836] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Apparent deficiency of soil mineral nutrients often triggers specific physio-morphological changes in plants, and some of these changes could also inadvertently increase the ability of plants to mobilize radionuclides from stable mineral forms. This work, through a series of sand-culture, hydroponics, and batch-equilibration experiments, investigated the differential ability of root exudates of Andropogon virginicus grown under conditions with variable phosphorus (P) availability (KH2PO4, FePO4, Ca3(PO4)2, and no P) to solubilize uranium (U) from the uranyl phosphate mineral Chernikovite. The mineral form of P, and hence the bioavailability of P, affected the overall composition of the root exudates. The lower bioavailable forms of P (FePO4 and Ca3(PO4)2), but not the complete absence of P, resulted in a higher abundance of root metabolites with chelating capacity at 72 hrs after treatment application. In treatments with lower P-bioavailability, the physiological amino acid concentration inside of the roots increased, whereas the concentration of organic acids in the roots decreased due to the active exudation. In batch dissolution experiments, the organic acids, but not amino acids, increase the dissolution U from Chernikovite. The root exudate matrix of plants exposed to low available forms of P induced a >60% increase in U dissolution from Chernikovite due to 5-16 times greater abundance of organic acids in these treatments. However, this was ca. 70% of the theoretical dissolution achievable by this exudate matrix. These results highlight the potential of using active management of soil P as an effective tool to alter the plant-mediated mobilization of U in contaminated soil.
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Affiliation(s)
- Nimisha Edayilam
- Department of Plant & Environmental Sciences , Clemson University , Clemson , South Carolina 29634 , United States
| | - Dawn Montgomery
- Department of Environmental Engineering and Earth Sciences , Clemson University , 342 Computer Court , Anderson , South Carolina 29625 , United States
| | - Brennan Ferguson
- Department of Environmental Engineering and Earth Sciences , Clemson University , 342 Computer Court , Anderson , South Carolina 29625 , United States
| | - Amith S Maroli
- Department of Plant & Environmental Sciences , Clemson University , Clemson , South Carolina 29634 , United States
| | - Nicole Martinez
- Department of Environmental Engineering and Earth Sciences , Clemson University , 342 Computer Court , Anderson , South Carolina 29625 , United States
| | - Brian A Powell
- Department of Environmental Engineering and Earth Sciences , Clemson University , 342 Computer Court , Anderson , South Carolina 29625 , United States
| | - Nishanth Tharayil
- Department of Plant & Environmental Sciences , Clemson University , Clemson , South Carolina 29634 , United States
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16
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Pétriacq P, Williams A, Cotton A, McFarlane AE, Rolfe SA, Ton J. Metabolite profiling of non-sterile rhizosphere soil. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2017; 92:147-162. [PMID: 28742258 PMCID: PMC5639361 DOI: 10.1111/tpj.13639] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 07/11/2017] [Accepted: 07/12/2017] [Indexed: 05/10/2023]
Abstract
Rhizosphere chemistry is the sum of root exudation chemicals, their breakdown products and the microbial products of soil-derived chemicals. To date, most studies about root exudation chemistry are based on sterile cultivation systems, which limits the discovery of microbial breakdown products that act as semiochemicals and shape microbial rhizosphere communities. Here, we present a method for untargeted metabolic profiling of non-sterile rhizosphere soil. We have developed an experimental growth system that enables the collection and analysis of rhizosphere chemicals from different plant species. High-throughput sequencing of 16SrRNA genes demonstrated that plants in the growth system support a microbial rhizosphere effect. To collect a range of (a)polar chemicals from the system, we developed extraction methods that do not cause detectable damage to root cells or soil-inhabiting microbes, thus preventing contamination with cellular metabolites. Untargeted metabolite profiling by UPLC-Q-TOF mass spectrometry, followed by uni- and multivariate statistical analyses, identified a wide range of secondary metabolites that are enriched in plant-containing soil, compared with control soil without roots. We show that the method is suitable for profiling the rhizosphere chemistry of Zea mays (maize) in agricultural soil, thereby demonstrating the applicability to different plant-soil combinations. Our study provides a robust method for the comprehensive metabolite profiling of non-sterile rhizosphere soil, which represents a technical advance towards the establishment of causal relationships between the chemistry and microbial composition of the rhizosphere.
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Affiliation(s)
- Pierre Pétriacq
- Plant Production and Protection (P) Institute for Translational Plant & Soil BiologyDepartment of Animal and Plant SciencesThe University of SheffieldSheffieldS10 2TNUK
- biOMICS FacilityDepartment of Animal and Plant SciencesThe University of SheffieldSheffieldS10 2TNUK
- Department of Animal and Plant SciencesThe University of SheffieldSheffieldS10 2TNUK
| | - Alex Williams
- Department of Animal and Plant SciencesThe University of SheffieldSheffieldS10 2TNUK
| | - Anne Cotton
- Department of Animal and Plant SciencesThe University of SheffieldSheffieldS10 2TNUK
| | | | - Stephen A. Rolfe
- Plant Production and Protection (P) Institute for Translational Plant & Soil BiologyDepartment of Animal and Plant SciencesThe University of SheffieldSheffieldS10 2TNUK
- Department of Animal and Plant SciencesThe University of SheffieldSheffieldS10 2TNUK
| | - Jurriaan Ton
- Plant Production and Protection (P) Institute for Translational Plant & Soil BiologyDepartment of Animal and Plant SciencesThe University of SheffieldSheffieldS10 2TNUK
- Department of Animal and Plant SciencesThe University of SheffieldSheffieldS10 2TNUK
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17
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Baltrus DA. Adaptation, specialization, and coevolution within phytobiomes. CURRENT OPINION IN PLANT BIOLOGY 2017; 38:109-116. [PMID: 28545003 DOI: 10.1016/j.pbi.2017.04.023] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 04/26/2017] [Indexed: 05/03/2023]
Abstract
Growth patterns of individual plants and evolutionary trajectories of plant communities are intimately linked with and are critically affected by host-associated microbiomes. Research across systems has begun to shed light on how these phytobiomes are established under laboratory and natural conditions, and have cultivated hope that a better understanding of the governing principles for host-microbe interactions can guide attempts to engineer microbiomes to boost agricultural yields. One important, yet relatively understudied, parameter in regards to phytobiome membership is the degree to which specialization and coevolution between plant species and microbes provides structure to these communities. In this article, I provide an overview of mechanisms enabling adaptation and specialization of phytobiome communities to host plants as well as the potential for plants themselves to recruit and cultivate beneficial interactions. I further explore the possibility of host-beneficial microbe coevolution and suggest particular situations that could promote the evolution of such close-knit partnerships. It is my hope that this overview will encourage future experiments that can begin to fill in this black box of ecological and evolutionary interactions across phytobiomes.
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Affiliation(s)
- David A Baltrus
- School of Plant Sciences, University of Arizona, Tucson, AZ 85721, United States; School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, AZ 85721, United States.
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18
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Fernández M, Matilla MA, Ortega Á, Krell T. Metabolic Value Chemoattractants Are Preferentially Recognized at Broad Ligand Range Chemoreceptor of Pseudomonas putida KT2440. Front Microbiol 2017; 8:990. [PMID: 28620365 PMCID: PMC5449446 DOI: 10.3389/fmicb.2017.00990] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 05/17/2017] [Indexed: 12/18/2022] Open
Abstract
Bacteria have evolved a wide range of chemoreceptors with different ligand specificities. Typically, chemoreceptors bind ligands with elevated specificity and ligands serve as growth substrates. However, there is a chemoreceptor family that has a broad ligand specificity including many compounds that are not of metabolic value. To advance the understanding of this family, we have used the PcaY_PP (PP2643) chemoreceptor of Pseudomonas putida KT2440 as a model. Using Isothermal Titration Calorimetry we showed here that the recombinant ligand binding domain (LBD) of PcaY_PP recognizes 17 different C6-ring containing carboxylic acids with KD values between 3.7 and 138 μM and chemoeffector affinity correlated with the magnitude of the chemotactic response. Mutation of the pcaY_PP gene abolished chemotaxis to these compounds; phenotype that was restored following gene complementation. Growth experiments using PcaY_PP ligands as sole C-sources revealed functional relationships between their metabolic potential and affinity for the chemoreceptor. Thus, only 7 PcaY_PP ligands supported growth and their KD values correlated with the length of the bacterial lag phase. Furthermore, PcaY_PP ligands that did not support growth had significantly higher KD values than those that did. The receptor has thus binds preferentially compounds that serve as C-sources and amongst them those that rapidly promote growth. Tightest binding compounds were quinate, shikimate, 3-dehydroshikimate and protocatechuate, which are at the interception of the biosynthetic shikimate and catabolic quinate pathways. Analytical ultracentrifugation studies showed that ligand free PcaY_PP-LBD is present in a monomer-dimer equilibrium (KD = 57.5 μM). Ligand binding caused a complete shift to the dimeric state, which appears to be a general feature of four-helix bundle LBDs. This study indicates that the metabolic potential of compounds is an important parameter in the molecular recognition by broad ligand range chemoreceptors.
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Affiliation(s)
- Matilde Fernández
- Estación Experimental del Zaidín, Department of Environmental Protection, Consejo Superior de Investigaciones Científicas,Granada, Spain
| | - Miguel A Matilla
- Estación Experimental del Zaidín, Department of Environmental Protection, Consejo Superior de Investigaciones Científicas,Granada, Spain
| | - Álvaro Ortega
- Estación Experimental del Zaidín, Department of Environmental Protection, Consejo Superior de Investigaciones Científicas,Granada, Spain
| | - Tino Krell
- Estación Experimental del Zaidín, Department of Environmental Protection, Consejo Superior de Investigaciones Científicas,Granada, Spain
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