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Tao K, Jensen IT, Zhang S, Villa-Rodríguez E, Blahovska Z, Salomonsen CL, Martyn A, Björgvinsdóttir ÞN, Kelly S, Janss L, Glasius M, Waagepetersen R, Radutoiu S. Nitrogen and Nod factor signaling determine Lotus japonicus root exudate composition and bacterial assembly. Nat Commun 2024; 15:3436. [PMID: 38653767 DOI: 10.1038/s41467-024-47752-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 04/09/2024] [Indexed: 04/25/2024] Open
Abstract
Symbiosis with soil-dwelling bacteria that fix atmospheric nitrogen allows legume plants to grow in nitrogen-depleted soil. Symbiosis impacts the assembly of root microbiota, but it is unknown how the interaction between the legume host and rhizobia impacts the remaining microbiota and whether it depends on nitrogen nutrition. Here, we use plant and bacterial mutants to address the role of Nod factor signaling on Lotus japonicus root microbiota assembly. We find that Nod factors are produced by symbionts to activate Nod factor signaling in the host and that this modulates the root exudate profile and the assembly of a symbiotic root microbiota. Lotus plants with different symbiotic abilities, grown in unfertilized or nitrate-supplemented soils, display three nitrogen-dependent nutritional states: starved, symbiotic, or inorganic. We find that root and rhizosphere microbiomes associated with these states differ in composition and connectivity, demonstrating that symbiosis and inorganic nitrogen impact the legume root microbiota differently. Finally, we demonstrate that selected bacterial genera characterizing state-dependent microbiomes have a high level of accurate prediction.
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Affiliation(s)
- Ke Tao
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Ib T Jensen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
- Department of Mathematical Sciences, Aalborg University, Aarhus, Denmark
| | - Sha Zhang
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Eber Villa-Rodríguez
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Zuzana Blahovska
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | | | - Anna Martyn
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
- Department of Plant-Microbe Interactions, Max-Planck-Institute for Plant Breeding Research, Cologne, Germany
| | | | - Simon Kelly
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
- Biotechnology, Lincoln Agritech, Canterbury, New Zealand
| | - Luc Janss
- Center for Quantitative Genetics and Genomics, Aarhus University, Aarhus, Denmark
| | | | | | - Simona Radutoiu
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.
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Määttä T, Malhotra A. The hidden roots of wetland methane emissions. GLOBAL CHANGE BIOLOGY 2024; 30:e17127. [PMID: 38337165 DOI: 10.1111/gcb.17127] [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: 09/01/2023] [Revised: 11/24/2023] [Accepted: 12/02/2023] [Indexed: 02/12/2024]
Abstract
Wetlands are the largest natural source of methane (CH4 ) globally. Climate and land use change are expected to alter CH4 emissions but current and future wetland CH4 budgets remain uncertain. One important predictor of wetland CH4 flux, plants, play an important role in providing substrates for CH4 -producing microbes, increasing CH4 consumption by oxygenating the rhizosphere, and transporting CH4 from soils to the atmosphere. Yet, there remain various mechanistic knowledge gaps regarding the extent to which plant root systems and their traits influence wetland CH4 emissions. Here, we present a novel conceptual framework of the relationships between a range of root traits and CH4 processes in wetlands. Based on a literature review, we propose four main CH4 -relevant categories of root function: gas transport, carbon substrate provision, physicochemical influences and root system architecture. Within these categories, we discuss how individual root traits influence CH4 production, consumption, and transport (PCT). Our findings reveal knowledge gaps concerning trait functions in physicochemical influences, and the role of mycorrhizae and temporal root dynamics in PCT. We also identify priority research needs such as integrating trait measurements from different root function categories, measuring root-CH4 linkages along environmental gradients, and following standardized root ecology protocols and vocabularies. Thus, our conceptual framework identifies relevant belowground plant traits that will help improve wetland CH4 predictions and reduce uncertainties in current and future wetland CH4 budgets.
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Affiliation(s)
- Tiia Määttä
- Department of Geography, University of Zürich, Zürich, Switzerland
| | - Avni Malhotra
- Department of Geography, University of Zürich, Zürich, Switzerland
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, USA
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Mészárošová L, Kuťáková E, Kohout P, Münzbergová Z, Baldrian P. Plant effects on microbiome composition are constrained by environmental conditions in a successional grassland. ENVIRONMENTAL MICROBIOME 2024; 19:8. [PMID: 38268048 PMCID: PMC10809484 DOI: 10.1186/s40793-024-00550-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2023] [Accepted: 01/12/2024] [Indexed: 01/26/2024]
Abstract
BACKGROUND Below-ground microbes mediate key ecosystem processes and play a vital role in plant nutrition and health. Understanding the composition of the belowground microbiome is therefore important for maintaining ecosystem stability. The structure of the belowground microbiome is largely determined by individual plants, but it is not clear how far their influence extends and, conversely, what the influence of other plants growing nearby is. RESULTS To determine the extent to which a focal host plant influences its soil and root microbiome when growing in a diverse community, we sampled the belowground bacterial and fungal communities of three plant species across a primary successional grassland sequence. The magnitude of the host effect on its belowground microbiome varied among microbial groups, soil and root habitats, and successional stages characterized by different levels of diversity of plant neighbours. Soil microbial communities were most strongly structured by sampling site and showed significant spatial patterns that were partially driven by soil chemistry. The influence of focal plant on soil microbiome was low but tended to increase with succession and increasing plant diversity. In contrast, root communities, particularly bacterial, were strongly structured by the focal plant species. Importantly, we also detected a significant effect of neighbouring plant community composition on bacteria and fungi associating with roots of the focal plants. The host influence on root microbiome varied across the successional grassland sequence and was highest in the most diverse site. CONCLUSIONS Our results show that in a species rich natural grassland, focal plant influence on the belowground microbiome depends on environmental context and is modulated by surrounding plant community. The influence of plant neighbours is particularly pronounced in root communities which may have multiple consequences for plant community productivity and stability, stressing the importance of plant diversity for ecosystem functioning.
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Affiliation(s)
- Lenka Mészárošová
- Institute of Microbiology of the CAS, v. v. i., Vídeňská 1083, Prague 4, 142 20, Czech Republic.
- University of Chemistry and Technology, Technická 5, Praha 6, 166 28, Czech Republic.
| | - Eliška Kuťáková
- Institute of Botany of the CAS, v. v. i., Zámek 1, Průhonice, 252 43, Czech Republic
- Department of Botany, Faculty of Science, Charles University in Prague, Benátská 2, Prague 2, 128 01, Czech Republic
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Skogsmarksgränd 17, Umeå, 901 83, Sweden
| | - Petr Kohout
- Institute of Microbiology of the CAS, v. v. i., Vídeňská 1083, Prague 4, 142 20, Czech Republic
| | - Zuzana Münzbergová
- Institute of Botany of the CAS, v. v. i., Zámek 1, Průhonice, 252 43, Czech Republic
- Department of Botany, Faculty of Science, Charles University in Prague, Benátská 2, Prague 2, 128 01, Czech Republic
| | - Petr Baldrian
- Institute of Microbiology of the CAS, v. v. i., Vídeňská 1083, Prague 4, 142 20, Czech Republic
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Jiang Z, Fu Y, Zhou L, He Y, Zhou G, Dietrich P, Long J, Wang X, Jia S, Ji Y, Jia Z, Song B, Liu R, Zhou X. Plant growth strategy determines the magnitude and direction of drought-induced changes in root exudates in subtropical forests. GLOBAL CHANGE BIOLOGY 2023; 29:3476-3488. [PMID: 36931867 DOI: 10.1111/gcb.16685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 02/27/2023] [Accepted: 03/08/2023] [Indexed: 05/16/2023]
Abstract
Root exudates are an important pathway for plant-microbial interactions and are highly sensitive to climate change. However, how extreme drought affects root exudates and the main components, as well as species-specific differences in response magnitude and direction, are poorly understood. In this study, root exudation rates of total carbon (C) and its components (e.g., sugar, organic acid, and amino acid) were measured under the control and extreme drought treatments (i.e., 70% throughfall reduction) by in situ collection of four tree species with different growth rates in a subtropical forest. We also quantified soil properties, root morphological traits, and mycorrhizal infection rates to examine the driving factors underlying variations in root exudation. Our results showed that extreme drought significantly decreased root exudation rates of total C, sugar, and amino acid by 17.8%, 30.8%, and 35.0%, respectively, but increased root exudation rate of organic acid by 38.6%, which were largely associated with drought-induced changes in tree growth rates, root morphological traits, and mycorrhizal infection rates. Specifically, trees with relatively high growth rates were more responsive to drought for root exudation rates compared with those with relatively low growth rates, which were closely related to root morphological traits and mycorrhizal infection rates. These findings highlight the importance of plant growth strategy in mediating drought-induced changes in root exudation rates. The coordinations among root exudation rates, root morphological traits, and mycorrhizal symbioses in response to drought could be incorporated into land surface models to improve the prediction of climate change impacts on rhizosphere C dynamics in forest ecosystems.
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Affiliation(s)
- Zheng Jiang
- Center for Global Change and Ecological Forecasting, Tiantong National Field Station for Forest Ecosystem, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, China
| | - Yuling Fu
- Center for Global Change and Ecological Forecasting, Tiantong National Field Station for Forest Ecosystem, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, China
| | - Lingyan Zhou
- Center for Global Change and Ecological Forecasting, Tiantong National Field Station for Forest Ecosystem, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, China
| | - Yanghui He
- Northeast Asia Ecosystem Carbon Sink Research Center (NACC), Center for Ecological Research, Key Laboratory of Sustainable Forest Ecosystem Management-Ministry of Education, School of Forestry, Northeast Forestry University, Harbin, China
| | - Guiyao Zhou
- Center for Global Change and Ecological Forecasting, Tiantong National Field Station for Forest Ecosystem, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, China
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
| | - Peter Dietrich
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
| | - Jilan Long
- Center for Global Change and Ecological Forecasting, Tiantong National Field Station for Forest Ecosystem, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, China
| | - Xinxin Wang
- Center for Global Change and Ecological Forecasting, Tiantong National Field Station for Forest Ecosystem, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, China
| | - Shuxian Jia
- Center for Global Change and Ecological Forecasting, Tiantong National Field Station for Forest Ecosystem, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, China
| | - Yuhuang Ji
- Center for Global Change and Ecological Forecasting, Tiantong National Field Station for Forest Ecosystem, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, China
| | - Zhen Jia
- Center for Global Change and Ecological Forecasting, Tiantong National Field Station for Forest Ecosystem, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, China
| | - Bingqian Song
- Center for Global Change and Ecological Forecasting, Tiantong National Field Station for Forest Ecosystem, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, China
| | - Ruiqiang Liu
- Northeast Asia Ecosystem Carbon Sink Research Center (NACC), Center for Ecological Research, Key Laboratory of Sustainable Forest Ecosystem Management-Ministry of Education, School of Forestry, Northeast Forestry University, Harbin, China
| | - Xuhui Zhou
- Center for Global Change and Ecological Forecasting, Tiantong National Field Station for Forest Ecosystem, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, China
- Northeast Asia Ecosystem Carbon Sink Research Center (NACC), Center for Ecological Research, Key Laboratory of Sustainable Forest Ecosystem Management-Ministry of Education, School of Forestry, Northeast Forestry University, Harbin, China
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Becker MF, Klueken AM, Knief C. Effects of above ground pathogen infection and fungicide application on the root-associated microbiota of apple saplings. ENVIRONMENTAL MICROBIOME 2023; 18:43. [PMID: 37245023 DOI: 10.1186/s40793-023-00502-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 05/14/2023] [Indexed: 05/29/2023]
Abstract
BACKGROUND The root-associated microbiome has been of keen research interest especially in the last decade due to the large potential for increasing overall plant performance in agricultural systems. Knowledge about the impact of above ground plant disturbances on the root-associated microbiome remains limited. We addressed this by focusing on two potential impacts, foliar pathogen infection alone and in combination with the application of a plant health protecting product. We hypothesized that these lead to plant-mediated responses in the rhizosphere microbiota. RESULTS The effects of an infection of greenhouse grown apple saplings with either Venturia inaequalis or Podosphaera leucotricha as foliar pathogen, as well as the combined effect of P. leucotricha infection and foliar application of the synthetic plant health protecting product Aliette (active ingredient: fosetyl-aluminum), were studied on the root-associated microbiota. The bacterial community structure of rhizospheric soil and endospheric root material was characterized post-infection, using 16S rRNA gene amplicon sequencing. With increasing disease severity both pathogens led to changes in the rhizosphere and endosphere bacterial communities in comparison to uninfected plants (explained variance up to 17.7%). While the preventive application of Aliette on healthy plants two weeks prior inoculation did not induce changes in the root-associated microbiota, a second later application on the diseased plants decreased disease severity and resulted in differences of the rhizosphere bacterial community between infected and several of the cured plants, though differences were overall not statistically significant. CONCLUSIONS Foliar pathogen infections can induce plant-mediated changes in the root-associated microbiota, indicating that above ground disturbances are reflected in the below-ground microbiome, even though these become evident only upon severe leaf infection. The application of the fungicide Aliette on healthy plants itself did not induce any changes, but the application to diseased plants helped the plant to regain the microbiota of a healthy plant. These findings indicate that above ground agronomic management practices have implications for the root-associated microbiome, which should be considered in the context of microbiome management strategies.
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Affiliation(s)
- Maximilian Fernando Becker
- Institute of Crop Science and Resource Conservation - Molecular Biology of the Rhizosphere, University of Bonn, Nussallee 13, 53115, Bonn, Germany
| | - A Michael Klueken
- Crop Science Division, Disease Control Biology, Bayer AG, Alfred-Nobel-Str. 50, 40789, Monheim am Rhein, Germany
| | - Claudia Knief
- Institute of Crop Science and Resource Conservation - Molecular Biology of the Rhizosphere, University of Bonn, Nussallee 13, 53115, Bonn, Germany.
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Zhai W, Jiang W, Guo Q, Wang Z, Liu D, Zhou Z, Wang P. Existence of antibiotic pollutant in agricultural soil: Exploring the correlation between microbiome and pea yield. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 871:162152. [PMID: 36775170 DOI: 10.1016/j.scitotenv.2023.162152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 02/04/2023] [Accepted: 02/06/2023] [Indexed: 06/18/2023]
Abstract
Due to sewage irrigation, manure fertilizer application or other agricultural activities, antibiotics have been introduced into farmland as an emerging contaminant, existing with other agrochemicals. However, the potential influences of antibiotics on the efficiency of agrochemicals and crops health are still unclear. In this work, the effect of antibiotics on fertilization efficiency and pea yield was evaluated, and the mechanism was explored in view of soil microbiome. Nitrogen utilization and pea yield were decreased by antibiotics. In specific, the weight of seeds decreased 9.5 % by 5 mg/kg antibiotics and decreased 25.1 % by 50 mg/kg antibiotics. For N nutrient in pea, antibiotics resulted in 62.5 %-63.7 % decrease in amino acid content and 8.3 %-35.3 % decrease in inorganic-N content. Further research showed that antibiotics interfered with N cycle in soil, inhibiting urea decomposition and denitrification process by reducing function genes ureC, nirK and norB in soil, thus decreasing N availability. Meanwhile, antibiotics destroyed the enzyme function in N assimilation. This work evaluated the environmental risk of antibiotics from fertilization efficiency and N utilization in crop. Antibiotics could not only affect N cycle, limiting the decomposition of N fertilizer, but also affect N utilization in plants, thus affecting the yield and even the quality of leguminous crops.
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Affiliation(s)
- Wangjing Zhai
- Beijing Advanced Innovation Centre for Food Nutrition and Human Health, Department of Applied Chemistry, China Agricultural University, No. 2 West Yuanmingyuan Road, Beijing 100193, PR China
| | - Wenqi Jiang
- Beijing Advanced Innovation Centre for Food Nutrition and Human Health, Department of Applied Chemistry, China Agricultural University, No. 2 West Yuanmingyuan Road, Beijing 100193, PR China
| | - Qiqi Guo
- Beijing Advanced Innovation Centre for Food Nutrition and Human Health, Department of Applied Chemistry, China Agricultural University, No. 2 West Yuanmingyuan Road, Beijing 100193, PR China
| | - Zhixuan Wang
- Beijing Advanced Innovation Centre for Food Nutrition and Human Health, Department of Applied Chemistry, China Agricultural University, No. 2 West Yuanmingyuan Road, Beijing 100193, PR China
| | - Donghui Liu
- Beijing Advanced Innovation Centre for Food Nutrition and Human Health, Department of Applied Chemistry, China Agricultural University, No. 2 West Yuanmingyuan Road, Beijing 100193, PR China
| | - Zhiqiang Zhou
- Beijing Advanced Innovation Centre for Food Nutrition and Human Health, Department of Applied Chemistry, China Agricultural University, No. 2 West Yuanmingyuan Road, Beijing 100193, PR China
| | - Peng Wang
- Beijing Advanced Innovation Centre for Food Nutrition and Human Health, Department of Applied Chemistry, China Agricultural University, No. 2 West Yuanmingyuan Road, Beijing 100193, PR China.
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Zhang Y, Cheng Z, Li Q, Dai Q, Hu J. Responses of rhizosphere bacterial communities in newly reclaimed mudflat paddies to rice genotype and nitrogen fertilizer rate. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:38761-38774. [PMID: 36586025 DOI: 10.1007/s11356-022-25020-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 12/23/2022] [Indexed: 06/17/2023]
Abstract
The rhizosphere microbiome plays a vital role in crop growth and adaptation. However, the effects of rice genotype, nitrogen (N) fertilization, and their interactions on the rhizosphere bacterial communities in low fertility soil remain poorly understood. In this study, a two-factor field experiment was performed in newly reclaimed mudflat paddies characterized by poor fertility to analyze bacterial communities in the rhizosphere of Yongyou 2640 (japonica/indica hybrid rice, JIH) and Huaidao No.5 (japonica conventional rice, JC) under different N fertilizer rates. Results showed that genotype, followed by N fertilizer rate, was the primary factor affecting rhizobacteria diversity. Rhizobacteria diversity was higher in JIH than in JC and that of JIH and JC did not significantly change overall as N fertilizer rates but increased and decreased at N fertilizer rates of over 300 kg N ha-1, respectively. The inconsistent response was probably attributed to the difference in the increase of ammonium and/or nitrate in the rhizosphere of JIH and JC. Genotype explained approximately 26% of the variation in rhizosphere bacterial communities. Rhizosphere bacterial communities with N fertilizer rates of over 300 kg N ha-1 were more dissimilar to those without N fertilization relative to those with N fertilizer rates of below 300 kg N ha-1, which was mainly attributed to changes in the concentration of ammonium and/or nitrate. The relative abundances of some potential beneficial genera such as Salinimicrobium, Salegentibacter, Gillisia, and Anaerolinea in the rhizosphere of JC and Salegentibacter, Lysobacter, Nocardioides, and Pontibacter in the rhizosphere of JIH were increased under N fertilizer rates of less than 300 kg N ha-1 and positively correlated with rice yields, which indicate that changes in bacterial communities caused by N fertilization might be strongly associated with the improvement of rice yield. Overall, rhizosphere bacterial communities were more sensitive to genotype in newly reclaimed mudflat paddies and showed a consistent response to N fertilizer rates.
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Affiliation(s)
- Yang Zhang
- College of Environmental Science and Engineering, Yangzhou University, Yangzhou, 225127, China
- Key Laboratory of Arable Land Quality Monitoring and Evaluation, Ministry of Agriculture and Rural Affairs, Yangzhou University, Yangzhou, 225127, China
| | - Zhandou Cheng
- College of Environmental Science and Engineering, Yangzhou University, Yangzhou, 225127, China
| | - Qing Li
- Jiangsu Key Laboratory of Crop Genetic and Physiology/Jiangsu Key Laboratory of Crop Cultivation and Physiology/Jiangsu Co-Innovation Center for Modern Production Technology of Grain Crops/Research Institute of Rice Industrial Engineering Technology, Yangzhou University, Yangzhou, 225009, China
| | - Qigen Dai
- Jiangsu Key Laboratory of Crop Genetic and Physiology/Jiangsu Key Laboratory of Crop Cultivation and Physiology/Jiangsu Co-Innovation Center for Modern Production Technology of Grain Crops/Research Institute of Rice Industrial Engineering Technology, Yangzhou University, Yangzhou, 225009, China.
| | - Jian Hu
- College of Environmental Science and Engineering, Yangzhou University, Yangzhou, 225127, China
- Key Laboratory of Arable Land Quality Monitoring and Evaluation, Ministry of Agriculture and Rural Affairs, Yangzhou University, Yangzhou, 225127, China
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8
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Zandi P, Yang J, Darma A, Bloem E, Xia X, Wang Y, Li Q, Schnug E. Iron plaque formation, characteristics, and its role as a barrier and/or facilitator to heavy metal uptake in hydrophyte rice (Oryza sativa L.). ENVIRONMENTAL GEOCHEMISTRY AND HEALTH 2023; 45:525-559. [PMID: 35288837 DOI: 10.1007/s10653-022-01246-4] [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: 09/28/2021] [Accepted: 02/25/2022] [Indexed: 06/14/2023]
Abstract
The persistent bioavailability of toxic metal(oids) (TM) is undeniably the leading source of serious environmental problems. Through the transfer of these contaminants into food networks, sediments and the aquatic environmental pollution by TM serve as key routes for potential risks to soil and human health. The formation of iron oxyhydroxide plaque (IP) on the root surface of hydrophytes, particularly rice, has been linked to the impact of various abiotic and biotic factors. Radial oxygen loss has been identified as a key driver for the oxidation of rhizosphere ferrous iron (Fe2+) and its subsequent precipitation as low-to-high crystalline and/or amorphous Fe minerals on root surfaces as IP. Considering that each plant species has its unique capability of creating an oxidised rhizosphere under anaerobic conditions, the abundance of rhizosphere Fe2+, functional groups from organic matter decomposition and variations in binding capacities of Fe oxides, thus, impacting the mobility and interaction of several contaminants as well as toxic/non-toxic metals on the specific surface areas of the IP. More insight from wet extraction and advanced synchrotron-based analytical techniques has provided further evidence on how IP formation could significantly affect the fate of plant physiology and biomass production, particularly in contaminated settings. Collectively, this information sets the stage for the possible implementation of IP and related analytical protocols as a strategic framework for the management of rice and other hydrophytes, particularly in contaminated sceneries. Other confounding variables involved in IP formation, as well as operational issues related to some advanced analytical processes, should be considered.
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Affiliation(s)
- Peiman Zandi
- International Faculty of Applied Technology, Yibin University, Yibin, 644000, People's Republic of China
- Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing, 100081, People's Republic of China
| | - Jianjun Yang
- Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing, 100081, People's Republic of China.
| | - Aminu Darma
- Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing, 100081, People's Republic of China
- Department of Biological Sciences, Bayero University, Kano, Nigeria
| | - Elke Bloem
- Julius Kühn-Institut (JKI), Federal Research Centre for Cultivated Plants, Institute for Crop and Soil Science, Bundesallee 69, 38116, Braunschweig, Germany
| | - Xing Xia
- Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing, 100081, People's Republic of China
| | - Yaosheng Wang
- Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing, 100081, People's Republic of China
| | - Qian Li
- Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, People's Republic of China
| | - Ewald Schnug
- Department of Life Sciences, Institute for Plant Biology, Technical University of Braunschweig, 38106, Braunschweig, Germany
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9
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Duan M, Wang L, Song X, Zhang X, Wang Z, Lei J, Yan M. Assessment of the rhizosphere fungi and bacteria recruited by sugarcane during smut invasion. Braz J Microbiol 2023; 54:385-395. [PMID: 36371518 PMCID: PMC9944363 DOI: 10.1007/s42770-022-00871-6] [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: 02/22/2022] [Accepted: 11/07/2022] [Indexed: 11/15/2022] Open
Abstract
Whip smut is one of the most serious and widely spread sugarcane diseases. Plant-associated microbes play various roles in conferring advantages to the host plant. Understanding the microbes associated with sugarcane roots will help develop strategies for the biocontrol of smut. Therefore, the present study explored microbe-mediated sugarcane response to smut invasion via 16S rRNA and ITS metabarcoding survey of the rhizosphere soils of resistant and susceptible sugarcane varieties. The bacterial and fungal diversity in the rhizosphere soils differed between the resistant and susceptible varieties. The bacterial genera Sphingomonas, Microcoleus_Es-Yyy1400, Marmoricola, Reyranella, Promicromonospora, Iamia, Phenylobacterium, Aridibacter, Actinophytocola, and Edaphobacter and one fungal genus Cyphellophora were found associated with smut resistance in sugarcane. Detailed analysis revealed that the majority of bacteria were beneficial, including the actinomycete Marmoricola and Iamia and Reyranella with denitrification activity. Analysis of bacterial network interaction showed that three major groups interacted during smut invasion. Meanwhile, seven of these genera appeared to interact and promote each other's growth. Finally, functional annotation based on the Functional Annotation of Prokaryotic Taxa (FAPROTAX) database predicted that the abundant bacteria are dominated by oxygenic photoautotrophy, photoautotrophy, and phototrophy functions, which may be related to smut resistance in sugarcane. The present study thus provides new insights into the dynamics of the sugarcane rhizosphere microbial community during smut invasion.
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Affiliation(s)
- Mingzheng Duan
- Guangxi Key Laboratory of Sugarcane Biology, College of Agriculture, Guangxi University, 100 Daxue Rd, Nanning, 530004, China
| | - Lingqiang Wang
- Guangxi Key Laboratory of Sugarcane Biology, College of Agriculture, Guangxi University, 100 Daxue Rd, Nanning, 530004, China
| | - Xiupeng Song
- Sugarcane Research Institute, Guangxi Academy of Agricultural Sciences; Sugarcane Research Center, Chinese Academy of Agricultural Sciences; Key Laboratory of Sugarcane Biotechnology and Genetic Improvement (Guangxi); Ministry of Agriculture, Guangxi Key Laboratory of Sugarcane Genetic Improvement, Nanning, 530007, China
| | - Xiaoqiu Zhang
- Sugarcane Research Institute, Guangxi Academy of Agricultural Sciences; Sugarcane Research Center, Chinese Academy of Agricultural Sciences; Key Laboratory of Sugarcane Biotechnology and Genetic Improvement (Guangxi); Ministry of Agriculture, Guangxi Key Laboratory of Sugarcane Genetic Improvement, Nanning, 530007, China
| | - Zeping Wang
- Sugarcane Research Institute, Guangxi Academy of Agricultural Sciences; Sugarcane Research Center, Chinese Academy of Agricultural Sciences; Key Laboratory of Sugarcane Biotechnology and Genetic Improvement (Guangxi); Ministry of Agriculture, Guangxi Key Laboratory of Sugarcane Genetic Improvement, Nanning, 530007, China
| | - Jingchao Lei
- Sugarcane Research Institute, Guangxi Academy of Agricultural Sciences; Sugarcane Research Center, Chinese Academy of Agricultural Sciences; Key Laboratory of Sugarcane Biotechnology and Genetic Improvement (Guangxi); Ministry of Agriculture, Guangxi Key Laboratory of Sugarcane Genetic Improvement, Nanning, 530007, China
| | - Meixin Yan
- Sugarcane Research Institute, Guangxi Academy of Agricultural Sciences; Sugarcane Research Center, Chinese Academy of Agricultural Sciences; Key Laboratory of Sugarcane Biotechnology and Genetic Improvement (Guangxi); Ministry of Agriculture, Guangxi Key Laboratory of Sugarcane Genetic Improvement, Nanning, 530007, China.
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10
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Dumack K, Feng K, Flues S, Sapp M, Schreiter S, Grosch R, Rose LE, Deng Y, Smalla K, Bonkowski M. What Drives the Assembly of Plant-associated Protist Microbiomes? Investigating the Effects of Crop Species, Soil Type and Bacterial Microbiomes. Protist 2022; 173:125913. [PMID: 36257252 DOI: 10.1016/j.protis.2022.125913] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 08/24/2022] [Accepted: 09/22/2022] [Indexed: 12/30/2022]
Abstract
In a field experiment we investigated the influence of the environmental filters soil type (i.e. three contrasting soils) and plant species (i.e. lettuce and potato) identity on rhizosphere community assembly of Cercozoa, a dominant group of mostly bacterivorous soil protists. Plant species (14%) and rhizosphere origin (vs bulk soil) with 13%, together explained four times more variation in cercozoan beta diversity than the three soil types (7% explained variation). Our results clearly confirm the existence of plant species-specific protist communities. Network analyses of bacteria-Cercozoa rhizosphere communities identified scale-free small world topologies, indicating mechanisms of self-organization. While the assembly of rhizosphere bacterial communities is bottom-up controlled through the resource supply from root (secondary) metabolites, our results support the hypothesis that the net effect may depend on the strength of top-down control by protist grazers. Since grazing of protists has a strong impact on the composition and functioning of bacteria communities, protists expand the repertoire of plant genes by functional traits, and should be considered as 'protist microbiomes' in analogy to 'bacterial microbiomes'.
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Affiliation(s)
- Kenneth Dumack
- University of Cologne, Institute of Zoology, Terrestrial Ecology, Zülpicher Str. 47b, 50674 Köln, Germany; Cluster of Excellence on Plant Sciences (CEPLAS), University of Cologne, Germany.
| | - Kai Feng
- University of Cologne, Institute of Zoology, Terrestrial Ecology, Zülpicher Str. 47b, 50674 Köln, Germany; CAS Key Laboratory for Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
| | - Sebastian Flues
- University of Cologne, Institute of Zoology, Terrestrial Ecology, Zülpicher Str. 47b, 50674 Köln, Germany; Cluster of Excellence on Plant Sciences (CEPLAS), University of Cologne, Germany
| | - Melanie Sapp
- Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich Heine University, Population Genetics, Universitätsstrasse 1, 40225 Düsseldorf, Germany
| | - Susanne Schreiter
- Julius Kühn-Institut, Federal Research Centre for Cultivated Plants, Institute for Epidemiology and Pathogen Diagnostics, Messeweg 11-12, 38104 Braunschweig, Germany; Helmholtz Centre for Environmental Research GmbH (UFZ), Deptartment Soil System Science, Theodor-Lieser-Str.4, 06120 Halle, Germany
| | - Rita Grosch
- Leibniz Institute of Vegetable and Ornamental Crops (IGZ), Plant-Microbe Systems, Theodor-Echtermeyer-Weg 1, 14979 Großbeeren, Germany
| | - Laura E Rose
- Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich Heine University, Population Genetics, Universitätsstrasse 1, 40225 Düsseldorf, Germany
| | - Ye Deng
- CAS Key Laboratory for Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
| | - Kornelia Smalla
- Julius Kühn-Institut, Federal Research Centre for Cultivated Plants, Institute for Epidemiology and Pathogen Diagnostics, Messeweg 11-12, 38104 Braunschweig, Germany
| | - Michael Bonkowski
- University of Cologne, Institute of Zoology, Terrestrial Ecology, Zülpicher Str. 47b, 50674 Köln, Germany; Cluster of Excellence on Plant Sciences (CEPLAS), University of Cologne, Germany
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11
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Chertov O, Kuzyakov Y, Priputina I, Frolov P, Shanin V, Grabarnik P. Modelling the Rhizosphere Priming Effect in Combination with Soil Food Webs to Quantify Interaction between Living Plant, Soil Biota and Soil Organic Matter. PLANTS (BASEL, SWITZERLAND) 2022; 11:2605. [PMID: 36235471 PMCID: PMC9572548 DOI: 10.3390/plants11192605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 09/26/2022] [Accepted: 09/29/2022] [Indexed: 06/16/2023]
Abstract
A model of rhizosphere priming effect under impact of root exudate input into rhizosphere soil was developed as an important process of the plant-soil interaction. The model was based on the concept of nitrogen (N) mining, compensating for the N scarcity in exudates for microbial growth by accelerating SOM mineralisation. In the model, N deficiency for microbial growth is covered ("mined") by the increased SOM mineralisation depending on the C:N ratio of the soil and exudates. The new aspect in the model is a food web procedure, which calculates soil fauna feeding on microorganisms, the return of faunal by-products to SOM and mineral N production for root uptake. The model verification demonstrated similar magnitude of the priming effect in simulations as in the published experimental data. Model testing revealed high sensitivity of the simulation results to N content in exudates. Simulated CO2 emission from the priming can reach 10-40% of CO2 emission from the whole Ah horizon of boreal forest soil depending on root exudation rates. This modeling approach with including food web activity allows quantifying wider aspects of the priming effect functioning including ecologically important available N production.
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Affiliation(s)
- Oleg Chertov
- Department of Natural Sciences, Bingen University of Applied Sciences, Berlin Str. 109, 55411 Bingen, Germany
| | - Yakov Kuzyakov
- Department of Soil Science of Temperate Ecosystems, Department of Agricultural Soil Science, Georg-August-Universität Göttingen, Büsgenweg 2, 37077 Göttingen, Germany
- Agro-Technological Institute, RUDN University, 117198 Moscow, Russia
| | - Irina Priputina
- Institute of Physicochemical and Biological Problems in Soil Science, Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Institutskaya 2, 142290 Pushchino, Russia
| | - Pavel Frolov
- Institute of Physicochemical and Biological Problems in Soil Science, Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Institutskaya 2, 142290 Pushchino, Russia
| | - Vladimir Shanin
- Institute of Physicochemical and Biological Problems in Soil Science, Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Institutskaya 2, 142290 Pushchino, Russia
- Center for Forest Ecology and Productivity of the Russian Academy of Sciences, Profsoyuznaya st., 84/32, bld. 14, 117997 Moscow, Russia
| | - Pavel Grabarnik
- Institute of Physicochemical and Biological Problems in Soil Science, Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Institutskaya 2, 142290 Pushchino, Russia
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12
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Liu Q, Zhang L, Wang L, Wu Q, Li K, Guo X. Autotoxin affects the rhizosphere microbial community structure by influencing the secretory characteristics of grapevine roots. Front Microbiol 2022; 13:953424. [PMID: 35958141 PMCID: PMC9360756 DOI: 10.3389/fmicb.2022.953424] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 07/07/2022] [Indexed: 11/16/2022] Open
Abstract
Autotoxins secreted by roots into the soil can trigger rhizosphere microecological imbalances and affect root secretory properties resulting in conditions such as replanting disease. However, information on the effect of autotoxins on root secretion characteristics and regulation of the composition of rhizosphere microorganisms by altered root exudates is limited. In this study, autotoxin ρ-hydroxybenzoic acid (4-HBA) was added to the soil of potted grapevine seedlings, CO2 pulse-labeling, and DNA stable isotope probing were used to track the rhizosphere microbiome that assimilates root exudates. Bacterial and fungal microbiomes that assimilated plant-derived carbon were identified by high-throughput sequencing. Results showed that 4-HBA treatment altered bacterial and fungal communities in 13C-labeled organisms, with a lower abundance of beneficial bacteria (e.g., Gemmatimonas, Streptomyces, and Bacillus) and a higher abundance of potential pathogen fungi (e.g., Fusarium, Neocosmospora, Gibberella, and Fusicolla) by changing the composition of root exudates. The exogenous addition of upregulated compound mixtures of root exudates reduced the abundance of beneficial bacterial Bacillus and increased the abundance of potential pathogen fungi Gibberella. These results suggest that 4-HBA can alter root secretion properties and altered root exudates may enrich certain potential pathogens and reduce certain beneficial bacteria, thereby unbalancing the structure of the rhizosphere microbial community.
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Affiliation(s)
- Qianwen Liu
- Department of Pomology, College of Horticulture, Shenyang Agricultural University, Shenyang, China
| | - Liheng Zhang
- Department of Pomology, College of Horticulture, Shenyang Agricultural University, Shenyang, China
- Dalian Academy of Agricultural Sciences, Dalian, China
| | - Lu Wang
- Department of Pomology, College of Horticulture, Shenyang Agricultural University, Shenyang, China
| | - Qingchun Wu
- Department of Pomology, College of Horticulture, Shenyang Agricultural University, Shenyang, China
| | - Kun Li
- Department of Pomology, College of Horticulture, Shenyang Agricultural University, Shenyang, China
- *Correspondence: Kun Li,
| | - Xiuwu Guo
- Department of Pomology, College of Horticulture, Shenyang Agricultural University, Shenyang, China
- Xiuwu Guo,
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13
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Oppenheimer-Shaanan Y, Jakoby G, Starr ML, Karliner R, Eilon G, Itkin M, Malitsky S, Klein T. A dynamic rhizosphere interplay between tree roots and soil bacteria under drought stress. eLife 2022; 11:79679. [PMID: 35858113 PMCID: PMC9385208 DOI: 10.7554/elife.79679] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 07/17/2022] [Indexed: 12/04/2022] Open
Abstract
Root exudates are thought to play an important role in plant-microbial interactions. In return for nutrition, soil bacteria can increase the bioavailability of soil nutrients. However, root exudates typically decrease in situations such as drought, calling into question the efficacy of solvation and bacteria-dependent mineral uptake in such stress. Here, we tested the hypothesis of exudate-driven microbial priming on Cupressus saplings grown in forest soil in custom-made rhizotron boxes. A 1-month imposed drought and concomitant inoculations with a mix of Bacillus subtilis and Pseudomonas stutzeri, bacteria species isolated from the forest soil, were applied using factorial design. Direct bacteria counts and visualization by confocal microscopy showed that both bacteria associated with Cupressus roots. Interestingly, root exudation rates increased 2.3-fold with bacteria under drought, as well as irrigation. Forty-four metabolites in exudates were significantly different in concentration between irrigated and drought trees, including phenolic acid compounds and quinate. When adding these metabolites as carbon and nitrogen sources to bacterial cultures of both bacterial species, eight of nine metabolites stimulated bacterial growth. Importantly, soil phosphorous bioavailability was maintained only in inoculated trees, mitigating drought-induced decrease in leaf phosphorus and iron. Our observations of increased root exudation rate when drought and inoculation regimes were combined support the idea of root recruitment of beneficial bacteria, especially under water stress. The soil surrounding the roots of trees, termed the rhizosphere, is full of bacteria and other communities of microorganisms. Trees secrete organic compounds in to the soil which are thought to influence the behavior of bacteria in the rhizosphere. Specifically, these root secretions, or ‘exudates’, attract and feed soil bacteria, which, in return, release nutrients that benefit the tree. In 2020, a group of researchers found that some trees in the Mediterranean forest produce more exudates during the long dry season. This suggests that the compounds secreted by roots may help trees to tolerate stress conditions, such as drought. To test this hypothesis, Oppenheimer-Shaanan et al. – including some of the researchers involved in the 2020 study – grew young Cupressus sempervirens conifer trees in drought conditions that starved them of the nutrients phosphorous and iron. Each tree was planted in a custom-built box which allowed easy access to roots growing in the soil. Two species of bacteria from the forest soil C. sempervirens trees naturally live in were then added to the soil in each box. Microscopy revealed that both species of bacteria, which had been tagged with fluorescent markers, were attracted to the roots of the trees, boosting the bacterial community in the rhizosphere. Oppenheimer-Shaanan et al. found that the recruitment of the two bacterial species caused the rate at which exudates were secreted from the roots to increase. Compounds in the exudate stimulated the bacteria to grow. Ultimately, levels of phosphorous and iron in the leaves of the starved trees increased when in the presence of these soil bacteria. This suggests that bacteria in the rhizosphere helps trees to survive when they are under stress and have low levels of water. These findings provide further evidence that plants and bacteria can live together in symbiosis and benefit one another. This could have important implications for forest ecology and potentially how trees are grown in orchards and gardens. For example, specific bacteria and organic compounds in the rhizosphere may be able to improve tree health. However, further work is needed to investigate whether the exudate compounds identified in this study are found more widely in nature.
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Affiliation(s)
| | - Gilad Jakoby
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Maya L Starr
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Romiel Karliner
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Gal Eilon
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Maxim Itkin
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Sergey Malitsky
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Tamir Klein
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel
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14
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Lobanov V, Keesman KJ, Joyce A. Plants Dictate Root Microbial Composition in Hydroponics and Aquaponics. Front Microbiol 2022; 13:848057. [PMID: 35509321 PMCID: PMC9058158 DOI: 10.3389/fmicb.2022.848057] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 03/23/2022] [Indexed: 11/13/2022] Open
Abstract
The role of the microbial community in mediating fish and plant co-culture is often considered the black box of aquaponics. Despite widespread recognition regarding the dependency of plants on their rhizosphere, the extent to which upstream aquaculture influences downstream hydroponic root communities has been poorly described in the literature. In this study we performed a taxonomic survey (16S rRNA metabarcoding) of microbial communities originating in the facility water source, hydroponic nutrient solution (HNS) sump, nutrient supplemented biofilter effluent (BF) sump, and recirculating aquaculture system tanks stocked with Nile tilapia (Oreochromis niloticus). Lettuce (Lactuca sativa) was then grown using the HNS and BF effluent under sterilized or mature (prior aquaponics/hydroponics lettuce culture water) conditions, likewise, the influence of probiotic addition or inoculation with soil-grown lettuce rhizosphere was assessed. Compositional similarities across treatments suggest that under soil-less conditions, plants are able to exert a stronger discriminatory influence on their rhizosphere composition than is done by colonization from upstream sources. Furthermore, cluster dendrograms grouped the sterilized and unsterilized treatments more consistently together than hydroponics and aquaponics treatments. These findings contradict conventional beliefs that microbial communities in the water column colonize roots based on their presence alone, ignoring the role that plants play in rhizosphere community selection.
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Affiliation(s)
- Victor Lobanov
- Department of Marine Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Karel J. Keesman
- Mathematical and Statistical Methods Group – Biometris, Wageningen University & Research, Wageningen, Netherlands
| | - Alyssa Joyce
- Department of Marine Sciences, University of Gothenburg, Gothenburg, Sweden
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15
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Ajilogba CF, Olanrewaju OS, Babalola OO. Plant Growth Stage Drives the Temporal and Spatial Dynamics of the Bacterial Microbiome in the Rhizosphere of Vigna subterranea. Front Microbiol 2022; 13:825377. [PMID: 35250941 PMCID: PMC8891599 DOI: 10.3389/fmicb.2022.825377] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 01/10/2022] [Indexed: 11/23/2022] Open
Abstract
Bambara groundnut (BGN) is an underutilized legume commonly found in sub-Saharan Africa. It thrives in marginal soils and is resistant to drought stress. Several studies have been carried out on the nutritional properties of BGN, but very little is known about the effects of plant growth changes and development on rhizosphere bacterial dynamics and function. This study reports on the bacterial dynamics and function in the bulk and rhizosphere soils of BGN at different growth stages (vegetative, flowering, pod-filling, and maturation stages). Aside from the maturation stage that shows distinct community structure from the other growth stages, results obtained showed no significant differences in bacterial community structure among the other growth stages. At a closer level, Actinobacteria, Proteobacteria, and Acidobacteria were dominant in rhizosphere soils at all growth stages. The bulk soil had the least average phyla abundance, while the maturity stage was characterized by the highest average phyla abundance. Rubrobacter, Acidobacterium, and Skermanella were the most predominant genus. It was observed from the analysis of operational taxonomic units that there was significant change in the bacterial structure of the rhizosphere with a higher abundance of potential plant growth-promoting rhizobacteria, at the different growth stages, which include the genera Bacillus and Acidobacterium. Biomarker analysis revealed 7 and 4 highly significant bacterial biomarkers by linear discriminant analysis effect size and random forest analysis at the maturation stage, respectively. The results obtained in this study demonstrated that the bacterial communities of BGN rhizosphere microbiome dynamics and function are influenced by the plant’s growth stages.
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Affiliation(s)
- Caroline Fadeke Ajilogba
- Food Security and Safety Focus Area, Faculty of Natural and Agricultural Sciences, North-West University, Mmabatho, South Africa
- Agricultural Research Council, Natural Resources and Engineering, Division of Agrometeorology, Pretoria, South Africa
| | - Oluwaseyi Samuel Olanrewaju
- Food Security and Safety Focus Area, Faculty of Natural and Agricultural Sciences, North-West University, Mmabatho, South Africa
| | - Olubukola Oluranti Babalola
- Food Security and Safety Focus Area, Faculty of Natural and Agricultural Sciences, North-West University, Mmabatho, South Africa
- *Correspondence: Olubukola Oluranti Babalola,
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16
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Mafa‐Attoye TG, Borden KA, Alvarez DO, Thevathasan N, Isaac ME, Dunfield KE. Roots alter soil microbial diversity and interkingdom interactions in diversified agricultural landscapes. OIKOS 2022. [DOI: 10.1111/oik.08717] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
| | - Kira A. Borden
- Faculty of Land and Food Systems, Univ. of British Columbia Vancouver BC Canada
| | | | | | - Marney E. Isaac
- Dept of Physical&Environmental Sciences, Univ. of Toronto Scarborough Toronto ON Canada
| | - Kari E. Dunfield
- School of Environmental Sciences, Univ. of Guelph Guelph ON Canada
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17
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Ghatak A, Schindler F, Bachmann G, Engelmeier D, Bajaj P, Brenner M, Fragner L, Varshney RK, Subbarao GV, Chaturvedi P, Weckwerth W. Root exudation of contrasting drought-stressed pearl millet genotypes conveys varying biological nitrification inhibition (BNI) activity. BIOLOGY AND FERTILITY OF SOILS 2022; 58:291-306. [PMID: 35399158 PMCID: PMC8938368 DOI: 10.1007/s00374-021-01578-w] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 06/10/2021] [Accepted: 06/12/2021] [Indexed: 05/09/2023]
Abstract
UNLABELLED Roots secrete a vast array of low molecular weight compounds into the soil broadly referred to as root exudates. It is a key mechanism by which plants and soil microbes interact in the rhizosphere. The effect of drought stress on the exudation process and composition is rarely studied, especially in cereal crops. This study focuses on comparative metabolic profiling of the exudates from sensitive and tolerant genotypes of pearl millet after a period of drought stress. We employed a combined platform of gas and liquid chromatography coupled to mass spectrometry to cover both primary and secondary metabolites. The results obtained demonstrate that both genotype and drought stress have a significant impact on the concentration and composition of root exudates. The complexity and function of these differential root exudates are discussed. To reveal the potential effect of root exudates on the soil microbial community after a period of drought stress, we also tested for biological nitrification inhibition (BNI) activity. The analysis revealed a genotype-dependent enhancement of BNI activity after a defined period of drought stress. In parallel, we observed a genotype-specific relation of elongated root growth and root exudation under drought stress. These data suggest that the drought stress-dependent change in root exudation can manipulate the microbial soil communities to adapt and survive under harsh conditions. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1007/s00374-021-01578-w.
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Affiliation(s)
- Arindam Ghatak
- Molecular Systems Biology (MOSYS), Department of Functional and Evolutionary Ecology, Faculty of Life Sciences, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Florian Schindler
- Molecular Systems Biology (MOSYS), Department of Functional and Evolutionary Ecology, Faculty of Life Sciences, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Gert Bachmann
- Molecular Systems Biology (MOSYS), Department of Functional and Evolutionary Ecology, Faculty of Life Sciences, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Doris Engelmeier
- Molecular Systems Biology (MOSYS), Department of Functional and Evolutionary Ecology, Faculty of Life Sciences, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Prasad Bajaj
- Center of Excellence in Genomics and Systems Biology (CEGSB), International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Hyderabad, Telangana 502324 India
| | - Martin Brenner
- Molecular Systems Biology (MOSYS), Department of Functional and Evolutionary Ecology, Faculty of Life Sciences, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
- Vienna Metabolomics Center (VIME), University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Lena Fragner
- Molecular Systems Biology (MOSYS), Department of Functional and Evolutionary Ecology, Faculty of Life Sciences, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
- Vienna Metabolomics Center (VIME), University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Rajeev K. Varshney
- Center of Excellence in Genomics and Systems Biology (CEGSB), International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Hyderabad, Telangana 502324 India
- State Agricultural Biotechnology Centre Centre for Crop and Food Innovation, Murdoch University, Murdoch, WA 6150 Australia
| | - Guntur Venkata Subbarao
- Crop, Livestock, and Environment Division, International Research Center for Agricultural Sciences (JIRCAS), Tsukuba, Ibaraki 305-8686 Japan
| | - Palak Chaturvedi
- Molecular Systems Biology (MOSYS), Department of Functional and Evolutionary Ecology, Faculty of Life Sciences, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Wolfram Weckwerth
- Molecular Systems Biology (MOSYS), Department of Functional and Evolutionary Ecology, Faculty of Life Sciences, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
- Vienna Metabolomics Center (VIME), University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
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18
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Tulumello J, Chabert N, Rodriguez J, Long J, Nalin R, Achouak W, Heulin T. Rhizobium alamii improves water stress tolerance in a non-legume. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 797:148895. [PMID: 34346368 DOI: 10.1016/j.scitotenv.2021.148895] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 07/01/2021] [Accepted: 07/04/2021] [Indexed: 06/13/2023]
Abstract
With the increasing demand for alternative solutions to replace or optimize the use of synthetic fertilizers and pesticides, the inoculation of bacteria that can contribute to the growth and health of plants (PGPR) is essential. The properties classically sought in PGPR are the production of phytohormones and other growth-promoting molecules, and more rarely the production of exopolysaccharides. We compared the effect of two strains of exopolysaccharide-producing Rhizobium alamii on rapeseed grown in a calcareous silty-clay soil under water stress conditions or not. The effect of factors 'water stress' and 'inoculation' were evaluated on plant growth parameters and the diversity of microbiota associated to root and root-adhering soil compartments. Water stress resulted in a significant decrease in leaf area, shoot biomass and RAS/RT ratio (root-adhering soil/root tissues), as well as overall beta-diversity. Inoculation with R. alamii YAS34 and GBV030 under water-stress conditions produced the same shoot dry biomass compared to uninoculated treatment in absence of water stress, and both strains increased shoot biomass under water-stressed conditions (+7% and +15%, respectively). Only R. alamii GBV030 significantly increased shoot biomass under unstressed or water-stressed conditions compared to the non-inoculated control (+39% and +15%, respectively). Alpha-diversity of the root-associated microbiota after inoculation with R. alamii YAS34 was significantly reduced. Beta-diversity was significantly modified after inoculation with R. alamii GBV030 under unstressed conditions. LEfSe analysis identified characteristic bacterial families, Flavobacteriaceae and Comamonadaceae, in the RT and RAS compartments for the treatment inoculated by R. alamii GBV030 under unstressed conditions, as well as Halomonadaceae (RT) and several species belonging to Actinomycetales (RAS). We showed that R. alamii GBV030 had a PGPR effect on rapeseed growth, increasing its tolerance to water stress, probably involving its capacity to produce exopolysaccharides, and other plant growth-promoting (PGP) traits.
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Affiliation(s)
- Joris Tulumello
- Aix Marseille Univ, CEA, CNRS, BIAM, LEMiRE, Laboratory of Microbial Ecology of the Rhizosphere, ECCOREV FR 3098, Saint Paul-Lez-Durance F-13108, France; BioIntrant 139, Rue Philippe de Girard, Pertuis F-84120, France.
| | - Nicolas Chabert
- BioIntrant 139, Rue Philippe de Girard, Pertuis F-84120, France.
| | - Julie Rodriguez
- Aix Marseille Univ, CEA, CNRS, BIAM, LEMiRE, Laboratory of Microbial Ecology of the Rhizosphere, ECCOREV FR 3098, Saint Paul-Lez-Durance F-13108, France; BioIntrant 139, Rue Philippe de Girard, Pertuis F-84120, France.
| | - Justine Long
- BioIntrant 139, Rue Philippe de Girard, Pertuis F-84120, France.
| | - Renaud Nalin
- BioIntrant 139, Rue Philippe de Girard, Pertuis F-84120, France.
| | - Wafa Achouak
- Aix Marseille Univ, CEA, CNRS, BIAM, LEMiRE, Laboratory of Microbial Ecology of the Rhizosphere, ECCOREV FR 3098, Saint Paul-Lez-Durance F-13108, France.
| | - Thierry Heulin
- Aix Marseille Univ, CEA, CNRS, BIAM, LEMiRE, Laboratory of Microbial Ecology of the Rhizosphere, ECCOREV FR 3098, Saint Paul-Lez-Durance F-13108, France.
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19
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Dibner RR, Weaver AM, Brock MT, Custer GF, Morrison HG, Maignien L, Weinig C. Time outweighs the effect of host developmental stage on microbial community composition. FEMS Microbiol Ecol 2021; 97:6321163. [PMID: 34259857 DOI: 10.1093/femsec/fiab102] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 07/12/2021] [Indexed: 01/04/2023] Open
Abstract
Thousands of microbial taxa in the soil form symbioses with host plants, and due to their contribution to plant performance, these microbes are often considered an extension of the host genome. Given microbial effects on host performance, it is important to understand factors that govern microbial community assembly. Host developmental stage could affect rhizosphere microbial diversity while, alternatively, microbial assemblages could change simply as a consequence of time and the opportunity for microbial succession. Previous studies suggest that rhizosphere microbial assemblages shift across plant developmental stages, but time since germination is confounded with developmental stage. We asked how elapsed time and potential microbial succession relative to host development affected microbial diversity in the rhizosphere using monogenic flowering-time mutants of Arabidopsis thaliana. Under our experimental design, different developmental stages were present among host genotypes after the same amount of time following germination, e.g. at 76 days following germination some host genotypes were flowering while others were fruiting or senescing. We found that elapsed time was a strong predictor of microbial diversity whereas there were few differences among developmental stages. Our results support the idea that time and, likely, microbial succession more strongly affect microbial community assembly than host developmental stage.
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Affiliation(s)
- Reilly R Dibner
- University of Wyoming, Botany, USA; University of Wyoming, EPSCoR, USA
| | - A Monique Weaver
- The University of Iowa Roy J and Lucille A Carver College of Medicine, Molecular Otolaryngology and Renal Research Labs, Department of Otolaryngology-Head and Neck Surgery, USA; The University of Iowa, Interdisciplinary PhD Program in Genetics, USA
| | | | - Gordon F Custer
- University of Wyoming, Department of Ecosystem Science and Management, USA; University of Wyoming, Program in Ecology, USA
| | - Hilary G Morrison
- Marine Biological Laboratory, Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, USA
| | - Lois Maignien
- UBO, CNRS, IFREMER, France; Marine Biological Laboratory, Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, USA
| | - Cynthia Weinig
- University of Wyoming, Department of Botany, USA; University of Wyoming, Program in Ecology, USA; University of Wyoming, Department of Molecular Biology, USA
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20
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Lobanov VP, Combot D, Pelissier P, Labbé L, Joyce A. Improving Plant Health Through Nutrient Remineralization in Aquaponic Systems. FRONTIERS IN PLANT SCIENCE 2021; 12:683690. [PMID: 34194456 PMCID: PMC8236952 DOI: 10.3389/fpls.2021.683690] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 05/10/2021] [Indexed: 06/13/2023]
Abstract
The exploitation of readily bioavailable fish excreta as a source of plant nutrients lies at the cornerstone of aquaponics farming. Research on nutrient cycling in aquaponic systems has devoted considerable attention to the plant uptake of dissolved nutrients in fish excreta, however, the integration of particulate-bound nutrients into downstream hydroponic farming has remained elusive. The high amount of organic carbon present in fish sludge may lead to biofouling if directly incorporated into hydroponic circulation systems, reducing the utility of incorporating fish solids on a large scale. In this study, we implemented a novel treatment system capable of reducing the carbon and nitrogen load of fish solids to produce a liquid fertilizer for a downstream hydroponics unit. Lettuce (Lactuca sativa) fertilized with exclusively a commercial nutrient solution, the biofilter effluent (coupled aquaponic system), effluent from the solids treatment system, or the latter two combined were grown in nutrient flow technique gutters downstream of a recirculating aquaculture system stocked with rainbow trout (Oncorhynchus mykiss). While crop yields were lower for the aquaponic treatments compared to lettuce grown in a commercial nutrient solution, plant sap analysis demonstrated a contrasting picture with respect to internal nutrient concentrations. Lettuce grown in the commercial hydroponic solution were deficient in several mineral nutrients (Mg, Ca, Na, and Si) nor did they have higher iron concentrations despite the significantly higher EDTA-chelated aqueous iron (460 × greater than other treatments) in the nutrient solution. Nutrient uptake in the rhizosphere was not investigated on a molecular level, although stunted rhizosphere growth in the commercial nutrient solution control suggests a weakened capacity for nutrient uptake in comparison to other treatments. Alongside the remineralization of micronutrients, the solids treatment system addressed the common issue of excess carbon leading to biofouling via a total suspended solids reduction of 87.27% ± 9.95 during the coupled aquaponics cultivation period. Ultimately, these data lead to two important conclusions. Firstly, optimizing nutrient bioavailability is not synonymous to increasing the presence of a nutrient in the water column. Secondly, estimating ideal nutrient solution concentrations involves both preventing nutrient blocking and improving bioavailability.
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Affiliation(s)
- Victor P. Lobanov
- Department of Marine Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Doriane Combot
- PEIMA-INRAe, UE0937, Fish Farming Systems Experimental Facility, Sizun, France
| | - Pablo Pelissier
- PEIMA-INRAe, UE0937, Fish Farming Systems Experimental Facility, Sizun, France
| | - Laurent Labbé
- PEIMA-INRAe, UE0937, Fish Farming Systems Experimental Facility, Sizun, France
| | - Alyssa Joyce
- Department of Marine Sciences, University of Gothenburg, Gothenburg, Sweden
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21
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Methods for Root Exudate Collection and Analysis. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2021; 2232:291-303. [PMID: 33161555 DOI: 10.1007/978-1-0716-1040-4_22] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Plant root exudation has long been recognized as a vital communication system between plants and microbial communities populating the rhizosphere. Due to the high complexity of the collection process and analysis, a variety of techniques have been developed to mimic natural exudation conditions. In addition, significant progress improving existing techniques and developing new methodologies of root exudate collection and analysis have been made. However, optimal standard methods that compare closely with environmental soil conditions are not yet available. In this review, we provide an overview of all those topics and provide suggestions for improvement.
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22
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Zuzolo D, Guarino C, Tartaglia M, Sciarrillo R. Plant-Soil-Microbiota Combination for the Removal of Total Petroleum Hydrocarbons (TPH): An In-Field Experiment. Front Microbiol 2021; 11:621581. [PMID: 33584589 PMCID: PMC7873869 DOI: 10.3389/fmicb.2020.621581] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Accepted: 12/28/2020] [Indexed: 12/18/2022] Open
Abstract
The contamination of soil with total petroleum hydrocarbons (TPH) may result in dramatic consequences and needs great attention, as soil rehabilitation would need more effort from a sustainability perspective. However, there is still no known general method since the remediation technology is strictly site-specific. Adaptive biological system dynamics can play a key role in understanding and addressing the potential of situ-specific biological combinations for soil pollutants removal. The potential worst-case of TPH contamination reflects soil affected by heavy industrial activities, such as oil refineries. Therefore, the experimental trial was conducted on a 2,000 m2 area from a contaminated site located in northern Italy. We evaluated the remediation potential over time (270 days) assessing (i) the phytoremediation efficiency of two species of Poaceae (Festuca arundinacea Schreb. and Dactylis glomerata L.) and two species of Fabaceae (Medicago sativa L. and Lotus corniculatus L.) and (ii) the role of the indigenous bacteria flora and endo-mycorrhizae consortium addition in plant growth promotion. We also induced resistance to contamination stress in a field experiment. Thirty-three indigenous bacteria selected from the contaminated soils showed marked plant growth promotion. Moreover, functional metagenomics confirmed the metabolic capability of hydrocarbon-degrading microorganisms living in the polluted soil. Our data showed that soil enzymatic activities increased with hydrocarbon degradation rate after 60 days. Both Poaceae and Fabaceae resulted in remarkable remediation potential. Stress markers and antioxidant activity indicated that the selected plant species generally need some time to adapt to TPH stress. In conclusion, our evaluation implied both the rhizosphere effects and functional features of the plant and suggested that plants should (i) have marked tolerance to specific contaminants, (ii) be characterized by an extensive root system, and (iii) be susceptible to arbuscular mycorrhizal fungi (AMF) infection.
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Affiliation(s)
| | - Carmine Guarino
- Department of Science and Technology, University of Sannio, Benevento, Italy
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Chen T, Hu R, Zheng Z, Yang J, Fan H, Deng X, Yao W, Wang Q, Peng S, Li J. Soil Bacterial Community in the Multiple Cropping System Increased Grain Yield Within 40 Cultivation Years. FRONTIERS IN PLANT SCIENCE 2021; 12:804527. [PMID: 34987540 PMCID: PMC8721226 DOI: 10.3389/fpls.2021.804527] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 11/22/2021] [Indexed: 05/05/2023]
Abstract
The shortage of land resources restricts the sustainable development of agricultural production. Multiple cropping has been widely used in Southern China, but whether the continuous planting will cause a decline in soil quality and crop yield is unclear. To test whether multiple cropping could increase grain yield, we investigated the farmlands with different cultivation years (10-20 years, 20-40 years, and >40 years). Results showed that tobacco-rice multiple cropping rotation significantly increased soil pH, nitrogen nutrient content, and grain yield, and it increased the richness of the bacterial community. The farmland with 20-40 years of cultivation has the highest soil organic carbon (SOC), ammonium nitrogen, and grain yield, but there is no significant difference in the diversity and structure of the bacterial community in farmlands with different cultivation years. The molecular ecological network indicated that the stability of the bacterial community decreased across the cultivation years, which may result in a decline of farmland yields in multiple cropping system> 40 years. The Acidobacteria members as the keystone taxa (Zi ≥ 2.5 or Pi ≥ 0.62) appeared in the tobacco-rice multiple cropping rotation farmlands, and the highest abundance of Acidobacteria was found in the farmland with the highest SOC and ammonium nitrogen content, suggesting Acidobacteria Gp4, GP7, GP12, and GP17 are important taxa involved in the soil carbon and nitrogen cycle. Therefore, in this study, the multiple cropping systems for 20 years will not reduce the crop production potential, but they cannot last for more than 40 years. This study provides insights for ensuring soil quality and enhancing sustainable agricultural production capacity.
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Affiliation(s)
- Tao Chen
- College of Agronomy, Hunan Agricultural University, Changsha, China
- Hunan Tobacco Company Chenzhou Branch, Chenzhou, China
| | - Ruiwen Hu
- College of Agronomy, Hunan Agricultural University, Changsha, China
| | - Zhongyi Zheng
- College of Agronomy, Hunan Agricultural University, Changsha, China
| | - Jiayi Yang
- College of Agronomy, Hunan Agricultural University, Changsha, China
| | - Huan Fan
- College of Agronomy, Hunan Agricultural University, Changsha, China
| | | | - Wang Yao
- Hunan Tobacco Company Zhangjiajie Branch, Zhangjiajie, China
| | - Qiming Wang
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, China
| | - Shuguang Peng
- Hunan Tobacco Monopoly Bureau, Changsha, China
- *Correspondence: Shuguang Peng
| | - Juan Li
- College of Agronomy, Hunan Agricultural University, Changsha, China
- Juan Li
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24
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Dai HT, Zhu RB, Sun BW, Che CS, Hou LJ. Effects of Sea Animal Activities on Tundra Soil Denitrification and nirS- and nirK-Encoding Denitrifier Community in Maritime Antarctica. Front Microbiol 2020; 11:573302. [PMID: 33162954 PMCID: PMC7581892 DOI: 10.3389/fmicb.2020.573302] [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: 06/16/2020] [Accepted: 09/22/2020] [Indexed: 01/04/2023] Open
Abstract
In maritime Antarctica, sea animals, such as penguins or seals, provide a large amount of external nitrogen input into tundra soils, which greatly impact nitrogen cycle in tundra ecosystems. Denitrification, which is closely related with the denitrifiers, is a key step in nitrogen cycle. However, effects of sea animal activities on tundra soil denitrification and denitrifier community structures still have received little attention. Here, the abundance, activity, and diversity of nirS- and nirK-encoding denitrifiers were investigated in penguin and seal colonies, and animal-lacking tundra in maritime Antarctica. Sea animal activities increased the abundances of nirS and nirK genes, and the abundances of nirS genes were significantly higher than those of nirK genes (p < 0.05) in all tundra soils. Soil denitrification rates were significantly higher (p < 0.05) in animal colonies than in animal-lacking tundra, and they were significantly positively correlated (p < 0.05) with nirS gene abundances instead of nirK gene abundances, indicating that nirS-encoding denitrifiers dominated the denitrification in tundra soils. The diversity of nirS-encoding denitrifiers was higher in animal colonies than in animal-lacking tundra, but the diversity of nirK-encoding denitrifiers was lower. Both the compositions of nirS- and nirK-encoding denitrifiers were similar in penguin or seal colony soils. Canonical correspondence analysis indicated that the community structures of nirS- and nirK-encoding denitrifiers were closely related to tundra soil biogeochemical processes associated with penguin or seal activities: the supply of nitrate and ammonium from penguin guano or seal excreta, and low C:N ratios. In addition, the animal activity-induced vegetation presence or absence had an important effect on tundra soil denitrifier activities and nirK-encoding denitrifier diversities. This study significantly enhanced our understanding of the compositions and dynamics of denitrifier community in tundra ecosystems of maritime Antarctica.
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Affiliation(s)
- Hai-Tao Dai
- Anhui Province Key Laboratory of Polar Environment and Global Change, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, China
| | - Ren-Bin Zhu
- Anhui Province Key Laboratory of Polar Environment and Global Change, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, China
| | - Bo-Wen Sun
- Anhui Province Key Laboratory of Polar Environment and Global Change, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, China
| | - Chen-Shuai Che
- Anhui Province Key Laboratory of Polar Environment and Global Change, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, China
| | - Li-Jun Hou
- State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, China
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25
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Pongrac P, Castillo-Michel H, Reyes-Herrera J, Hancock RD, Fischer S, Kelemen M, Thompson JA, Wright G, Likar M, Broadley MR, Vavpetič P, Pelicon P, White PJ. Effect of phosphorus supply on root traits of two Brassica oleracea L. genotypes. BMC PLANT BIOLOGY 2020; 20:368. [PMID: 32758143 PMCID: PMC7404929 DOI: 10.1186/s12870-020-02558-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 07/19/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND Phosphorus (P) deficiency limits crop production worldwide. Crops differ in their ability to acquire and utilise the P available. The aim of this study was to determine root traits (root exudates, root system architecture (RSA), tissue-specific allocation of P, and gene expression in roots) that (a) play a role in P-use efficiency and (b) contribute to large shoot zinc (Zn) concentration in Brassica oleracea. RESULTS Two B. oleracea accessions (var. sabellica C6, a kale, and var. italica F103, a broccoli) were grown in a hydroponic system or in a high-throughput-root phenotyping (HTRP) system where they received Low P (0.025 mM) or High P (0.25 mM) supply for 2 weeks. In hydroponics, root and shoot P and Zn concentrations were measured, root exudates were profiled using both Fourier-Transform-Infrared spectroscopy and gas-chromatography-mass spectrometry and previously published RNAseq data from roots was re-examined. In HTRP experiments, RSA (main and lateral root number and lateral root length) was assessed and the tissue-specific distribution of P was determined using micro-particle-induced-X-ray emission. The C6 accession had greater root and shoot biomass than the F103 accession, but the latter had a larger shoot P concentration than the C6 accession, regardless of the P supply in the hydroponic system. The F103 accession had a larger shoot Zn concentration than the C6 accession in the High P treatment. Although the F103 accession had a larger number of lateral roots, which were also longer than in the C6 accession, the C6 accession released a larger quantity and number of polar compounds than the F103 accession. A larger number of P-responsive genes were found in the Low P treatment in roots of the F103 accession than in roots of the C6 accession. Expression of genes linked with "phosphate starvation" was up-regulated, while those linked with iron homeostasis were down-regulated in the Low P treatment. CONCLUSIONS The results illustrate large within-species variability in root acclimatory responses to P supply in the composition of root exudates, RSA and gene expression, but not in P distribution in root cross sections, enabling P sufficiency in the two B. oleracea accessions studied.
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Affiliation(s)
- Paula Pongrac
- Ecological Science Group, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK.
- Jožef Stefan Institute, Jamova 39, SI-1000, Ljubljana, Slovenia.
| | | | | | - Robert D Hancock
- Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - Sina Fischer
- Future Food Beacon of Excellence and the School of Biosciences, University of Nottingham, Nottingham, LE12 5RD, UK
| | - Mitja Kelemen
- Jožef Stefan Institute, Jamova 39, SI-1000, Ljubljana, Slovenia
- Jožef Stefan International Postgraduate School, Jamova 39, SI-1000, Ljubljana, Slovenia
| | - Jacqueline A Thompson
- Ecological Science Group, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - Gladys Wright
- Ecological Science Group, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - Matevž Likar
- Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, SI-1000, Ljubljana, Slovenia
| | - Martin R Broadley
- Plant and Crop Sciences Division, University of Nottingham, Loughborough, LE12 5RD, UK
| | - Primož Vavpetič
- Jožef Stefan Institute, Jamova 39, SI-1000, Ljubljana, Slovenia
| | - Primož Pelicon
- Jožef Stefan Institute, Jamova 39, SI-1000, Ljubljana, Slovenia
| | - Philip J White
- Ecological Science Group, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
- Distinguished Scientist Fellowship Program, King Saud University, Riyadh, 11451, Saudi Arabia
- College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
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Sasse J, Kosina SM, de Raad M, Jordan JS, Whiting K, Zhalnina K, Northen TR. Root morphology and exudate availability are shaped by particle size and chemistry in Brachypodium distachyon. PLANT DIRECT 2020; 4:e00207. [PMID: 32642632 PMCID: PMC7330624 DOI: 10.1002/pld3.207] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 02/04/2020] [Accepted: 02/11/2020] [Indexed: 05/26/2023]
Abstract
Root morphology and exudation define a plants' sphere of influence in soils. In turn, soil characteristics influence plant growth, morphology, root microbiome, and rhizosphere chemistry. Collectively, all these parameters have significant implications on the major biogeochemical cycles, crop yield, and ecosystem health. However, how plants are shaped by the physiochemistry of soil particles is still not well understood. We explored how particle size and chemistry of growth substrates affect root morphology and exudation of a model grass. We grew Brachypodium distachyon in glass beads with various sizes (0.5, 1, 2, 3 mm), as well as in sand (0.005, 0.25, 4 mm) and in clay (4 mm) particles and in particle-free hydroponic medium. Plant morphology, root weight, and shoot weight were measured. We found that particle size significantly influenced root fresh weight and root length, whereas root number and shoot weight remained constant. Next, plant exudation profiles were analyzed with mass spectrometry imaging and liquid chromatography-mass spectrometry. Mass spectrometry imaging suggested that both, root length and number shape root exudation. Exudate profiles were comparable for plants growing in glass beads or sand with various particles sizes, but distinct for plants growing in clay for in situ exudate collection. Clay particles were found to sorb 20% of compounds exuded by clay-grown plants, and 70% of compounds from a defined exudate medium. The sorbed compounds belonged to a range of chemical classes, among them nucleosides, organic acids, sugars, and amino acids. Some of the sorbed compounds could be desorbed by a rhizobacterium (Pseudomonas fluorescens WCS415), supporting its growth. This study demonstrates the effect of different characteristics of particles on root morphology, plant exudation and availability of nutrients to microorganisms. These findings further support the critical importance of the physiochemical properties of soils when investigating plant morphology, plant chemistry, and plant-microbe interactions.
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Affiliation(s)
- Joelle Sasse
- Environmental Genomics and Systems BiologyLawrence Berkeley National LaboratoryBerkeleyCAUSA
- Department of Plant and Microbial BiologyUniversity of ZurichZurichSwitzerland
| | - Suzanne M. Kosina
- Environmental Genomics and Systems BiologyLawrence Berkeley National LaboratoryBerkeleyCAUSA
| | - Markus de Raad
- Environmental Genomics and Systems BiologyLawrence Berkeley National LaboratoryBerkeleyCAUSA
| | - Jacob S. Jordan
- Environmental Genomics and Systems BiologyLawrence Berkeley National LaboratoryBerkeleyCAUSA
- Joint Genome InstituteLawrence Berkeley National LaboratoryBerkeleyCAUSA
| | - Katherine Whiting
- Environmental Genomics and Systems BiologyLawrence Berkeley National LaboratoryBerkeleyCAUSA
| | - Kateryna Zhalnina
- Environmental Genomics and Systems BiologyLawrence Berkeley National LaboratoryBerkeleyCAUSA
| | - Trent R. Northen
- Environmental Genomics and Systems BiologyLawrence Berkeley National LaboratoryBerkeleyCAUSA
- Joint Genome InstituteLawrence Berkeley National LaboratoryBerkeleyCAUSA
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27
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Saad MM, Eida AA, Hirt H. Tailoring plant-associated microbial inoculants in agriculture: a roadmap for successful application. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:3878-3901. [PMID: 32157287 PMCID: PMC7450670 DOI: 10.1093/jxb/eraa111] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 03/09/2020] [Indexed: 05/05/2023]
Abstract
Plants are now recognized as metaorganisms which are composed of a host plant associated with a multitude of microbes that provide the host plant with a variety of essential functions to adapt to the local environment. Recent research showed the remarkable importance and range of microbial partners for enhancing the growth and health of plants. However, plant-microbe holobionts are influenced by many different factors, generating complex interactive systems. In this review, we summarize insights from this emerging field, highlighting the factors that contribute to the recruitment, selection, enrichment, and dynamic interactions of plant-associated microbiota. We then propose a roadmap for synthetic community application with the aim of establishing sustainable agricultural systems that use microbial communities to enhance the productivity and health of plants independently of chemical fertilizers and pesticides. Considering global warming and climate change, we suggest that desert plants can serve as a suitable pool of potentially beneficial microbes to maintain plant growth under abiotic stress conditions. Finally, we propose a framework for advancing the application of microbial inoculants in agriculture.
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Affiliation(s)
- Maged M Saad
- DARWIN21, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Abdul Aziz Eida
- DARWIN21, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Heribert Hirt
- DARWIN21, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
- Institute of Plant Sciences Paris-Saclay (IPS2), Gif-sur-Yvette Cedex, France
- Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
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28
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Cavalieri A, Bak F, Garcia-Lemos AM, Weiner J, Nicolaisen MH, Nybroe O. Effects of Intra- and Interspecific Plant Density on Rhizosphere Bacterial Communities. Front Microbiol 2020; 11:1045. [PMID: 32528445 PMCID: PMC7264394 DOI: 10.3389/fmicb.2020.01045] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 04/27/2020] [Indexed: 11/13/2022] Open
Abstract
There have been very few studies on the effects of plant competition on the rhizosphere bacterial community. To investigate the impacts of intra- and interspecific plant competition, we analyzed the responses of rhizosphere bacterial communities to plant density as determined by 16S rRNA gene targeted sequencing. We included five weedy plant species growing in field soil in monocultures and mixed cultures at three densities in a greenhouse experiment. The rhizosphere bacterial community of each species changed more with density in a mixture of all five plant species than in monocultures, so intra- and interspecific plant competition had different effects on the bacterial community. For the dominant plant competitor, Centaurea cyanus, neither intra- nor interspecific competition had major effects on the composition of its rhizosphere bacterial communities. In contrast, the bacterial communities of the weakest competitor, Trifolium repens, were affected differently by intra- and interspecific competition. During increasing intraspecific competition T. repens maintained a highly specialized bacterial community dominated by Rhizobium; while during interspecific competition, the relative abundance of Rhizobium declined while other nitrogen fixing and potentially plant growth promoting taxa became more abundant. Contrary to previous observations made for soil microbial communities, the bacterial rhizosphere community of the weakest competitor did not become more similar to that of the dominant species. Thus, the process of competition, as well as the plant species themselves, determined the rhizosphere bacterial community. Our results emphasize the role of plant-plant interactions for rhizosphere bacterial communities. These effects may feedback to affect plant-plant interactions, and this is an important hypothesis for future research.
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Affiliation(s)
- Andrea Cavalieri
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Frederik Bak
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Adriana M Garcia-Lemos
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Jacob Weiner
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
| | | | - Ole Nybroe
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
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29
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Prudent M, Dequiedt S, Sorin C, Girodet S, Nowak V, Duc G, Salon C, Maron PA. The diversity of soil microbial communities matters when legumes face drought. PLANT, CELL & ENVIRONMENT 2020; 43:1023-1035. [PMID: 31884709 DOI: 10.1111/pce.13712] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 12/20/2019] [Accepted: 12/23/2019] [Indexed: 05/19/2023]
Abstract
The cultivation of legumes shows promise for the development of sustainable agriculture, but yield instability remains one of the main obstacles for its adoption. Here, we tested whether the yield stability (i.e., resistance and resilience) of pea plants subjected to drought could be enhanced by soil microbial diversity. We used a dilution approach to manipulate the microbial diversity, with a genotype approach to distinguish the effect of symbionts from that of microbial diversity as a whole. We investigated the physiology of plants in response to drought when grown on a soil containing high or low level of microbial diversity. Plants grown under high microbial diversity displayed higher productivity and greater resilience after drought. Yield losses were mitigated by 15% on average in the presence of high soil microbial diversity at sowing. Our study provides proof of concept that the soil microbial community as a whole plays a key role for yield stability after drought even in plant species living in relationships with microbial symbionts. These results emphasize the need to restore soil biodiversity for sustainable crop management and climate change adaptation.
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Affiliation(s)
- Marion Prudent
- Agroécologie, AgroSup Dijon, INRAE, University Bourgogne Franche-Comté, Dijon, France
| | - Samuel Dequiedt
- Agroécologie, AgroSup Dijon, INRAE, University Bourgogne Franche-Comté, Dijon, France
| | - Camille Sorin
- Agroécologie, AgroSup Dijon, INRAE, University Bourgogne Franche-Comté, Dijon, France
| | - Sylvie Girodet
- Agroécologie, AgroSup Dijon, INRAE, University Bourgogne Franche-Comté, Dijon, France
| | - Virginie Nowak
- Agroécologie, AgroSup Dijon, INRAE, University Bourgogne Franche-Comté, Dijon, France
| | - Gérard Duc
- Agroécologie, AgroSup Dijon, INRAE, University Bourgogne Franche-Comté, Dijon, France
| | - Christophe Salon
- Agroécologie, AgroSup Dijon, INRAE, University Bourgogne Franche-Comté, Dijon, France
| | - Pierre-Alain Maron
- Agroécologie, AgroSup Dijon, INRAE, University Bourgogne Franche-Comté, Dijon, France
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Wang J, Xiong Y, Zhang J, Lu X, Wei G. Naturally selected dominant weeds as heavy metal accumulators and excluders assisted by rhizosphere bacteria in a mining area. CHEMOSPHERE 2020; 243:125365. [PMID: 31759218 DOI: 10.1016/j.chemosphere.2019.125365] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 10/28/2019] [Accepted: 11/12/2019] [Indexed: 05/04/2023]
Abstract
Managers need more practical and promising plants for use in heavy metal phytoremediation. Although previous studies have identified the potential of some weeds and microbial strains in phytoremediation, the potential of dominant weeds and the relationship between weeds and their rhizosphere bacterial strains are still unknown. In our study, we examined dominant weeds in the Dabaoshan mine located in Guangdong province, China to test their abilities as heavy metal accumulators and excluders. Results suggest that Ludwigia prostrata exhibited the highest potential for accumulating Cu, Pb and Zn compared with the other plants. Specifically, L. prostrata accumulated 71.58, 130.76 and 454.72 mg kg-1 of Cu, Pb and Zn, respectively; the species' translocation factor of Zn was 2.04, indicating a high accumulation of Zn. In contrast, the Cd translocation factor (TF) of Digitaria sanguinalis was 0.18, significantly lower than that of other plant species examined. Our results suggest that Ludwigia prostrata hyperaccumulates Zn and may also serve as a potential candidate remediation plant for Cu and Pb due to its high absolute accumulation amount of Cu and Pb, while Digitaria sanguinalis may be a potential candidate as a Cd excluder. We also found that rhizosphere bacterial communities were shaped by individual dominant plant species. Chloroflexi was the most dominant phylum in accumulator plant such as Fimbristylis miliacea, while Cyanobacteria was the most dominant phylum in excluder plant such as Digitaria sanguinalis. Our study provides insights for selecting new weedy forbs and grasses, rhizosphere bacterial species and developing approaches for phytoremediation and phytostabilization.
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Affiliation(s)
- Jiaxin Wang
- Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Wushan Road, Tianhe District, Guangzhou, 510642, PR China
| | - Yue Xiong
- Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Wushan Road, Tianhe District, Guangzhou, 510642, PR China
| | - Jiaen Zhang
- Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Wushan Road, Tianhe District, Guangzhou, 510642, PR China; Guangdong Provincial Key Laboratory of Eco-Circular Agriculture, Guangzhou, 510642, PR China; Guangdong Engineering Research Center for Modern Eco-agriculture and Circular Agriculture, Guangzhou, PR China.
| | - Xuening Lu
- Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Wushan Road, Tianhe District, Guangzhou, 510642, PR China
| | - Guangchang Wei
- Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Wushan Road, Tianhe District, Guangzhou, 510642, PR China
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Chen C, Chen HYH, Chen X. Functional diversity enhances, but exploitative traits reduce tree mixture effects on microbial biomass. Funct Ecol 2019. [DOI: 10.1111/1365-2435.13459] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Chen Chen
- Faculty of Natural Resources Management Lakehead University Thunder Bay ON Canada
| | - Han Y. H. Chen
- Faculty of Natural Resources Management Lakehead University Thunder Bay ON Canada
- Key Laboratory for Humid Subtropical Eco‐geographical Processes of the Ministry of Education Fujian Normal University Fuzhou China
| | - Xinli Chen
- Faculty of Natural Resources Management Lakehead University Thunder Bay ON Canada
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Simon L, Haichar FEZ. Determination of Root Exudate Concentration in the Rhizosphere Using 13C Labeling. Bio Protoc 2019; 9:e3228. [PMID: 33655014 PMCID: PMC7854189 DOI: 10.21769/bioprotoc.3228] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 04/11/2019] [Accepted: 04/22/2019] [Indexed: 11/02/2022] Open
Abstract
One of the most remarkable metabolic features of plant roots is their ability to secrete a wide range of compounds into the rhizosphere, defined as the volume of soil around living roots. Around 5%-21% of total photosynthetically fixed carbon is transferred into the rhizosphere through root exudates. Until recently, studies on the quantity and quality of root exudates were conducted mostly under axenic or monoxenic in vitro conditions. Today, in situ assays are required to provide a better understanding of root exudates dynamics and role in plant-microbe interactions. By incubating plants with 13CO2 in situ for one week and quantifying 13C enrichment from the root-adhering soil using mass spectrometry, we were able to determine root exudate levels. Indeed, labeled substrate 13CO2 is converted into organic carbon via plant photosynthesis and transferred into the soil through root exudation. We assume that all 13C increases above natural abundance are mainly derived from exudates produced by 13C-labeled plants.
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Affiliation(s)
- Laurent Simon
- UMR5023 LEHNA, Université Lyon 1, CNRS, ENTPE, Univ Lyon, Université Claude Bernard Lyon 1, University of Lyon, Villeurbanne Cedex, France
| | - Feth el Zahar Haichar
- UMR CNR 5557, Laboratoire d’Ecologie Microbienne, UMR INRA 1418, Univ Lyon, Université Claude Bernard Lyon 1, University of Lyon, Villeurbanne Cedex, France
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