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Afridi MS, Schulman P, Lacerda VNC, Guimaraes RA, Vasconcelos de Medeiros FH. Long-term benefit contribution of chemical and biological nematicide in coffee nematode management in soil microbial diversity and crop yield perspectives. Microbiol Res 2024; 282:127638. [PMID: 38422858 DOI: 10.1016/j.micres.2024.127638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2023] [Revised: 01/04/2024] [Accepted: 02/05/2024] [Indexed: 03/02/2024]
Abstract
The plant-parasitic root-knot nematode Meloidogyne exigua causes significant damage and is an important threat in Coffea arabica plantations. The utilization of plant-beneficial microbes as biological control agents against sedentary endoparasitic nematodes has been a longstanding strategy. However, their application in field conditions to control root-knot nematodes and their interaction with the rhizospheric microbiota of coffee plants remain largely unexplored. This study aimed to investigate the effects of biological control agent-based bioproducts and a chemical nematicide, used in various combinations, on the control of root-knot nematodes and the profiling of the coffee plant rhizomicrobiome in a field trial. The commercially available biological products, including Trichoderma asperellum URM 5911 (Quality), Bacillus subtilis UFPEDA 764 (Rizos), Bacillus methylotrophicus UFPEDA 20 (Onix), and nematicide Cadusafos (Rugby), were applied to adult coffee plants. The population of second-stage juveniles (J2) and eggs, as well as plant yield, were evaluated over three consecutive years. However, no significant differences were observed between the control group and the groups treated with bioproducts and the nematicide. Furthermore, the diversity and community composition of bacteria, fungi, and eukaryotes in the rhizosphere soil of bioproduct-treated plants were evaluated. The dominant phyla identified in the 16 S, ITS2, and 18 S communities included Proteobacteria, Acidobacteria, Actinobacteria, Ascomycota, Mortierellomycota, and Cercozoa in both consecutive years. There were no significant differences detected in the Shannon diversity of 16 S, ITS2, and 18 S communities between the years of data. The application of a combination of T. asperellum, B. subtilis, and B. methylotrophicus, as well as the use of Cadusafos alone and in combination with T. asperellum, B. subtilis, and B. methylotrophicus, resulted in a significant reduction (26.08%, 39.13%, and 21.73%, respectively) in the relative abundance of Fusarium spp. Moreover, the relative abundance of Trichoderma spp. significantly increased by 500%, 200%, and 100% at the genus level, respectively, compared to the control treatment. By constructing a co-occurrence network, we discovered a complex network structure among the species in all the bioproduct-treated groups. However, our findings indicate that the introduction of exogenous beneficial microbes into field conditions was unable to modulate the existing microbiota significantly. These findings suggest that the applied bioproducts had no significant impact on the reshaping of the overall microbial diversity in the rhizosphere microbiome but rather recruited selected microrganisms and assured net return to the grower. The results underscore the intricate nature of the rhizosphere microbiome and suggest the necessity for alternate biocontrol strategies and a re-evaluation of agricultural practices to improve nematode control by aligning with the complex ecological interactions in the rhizosphere.
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Affiliation(s)
- Muhammad Siddique Afridi
- Department of Phytopathology, Federal University of Lavras, PO Box 3037, Lavras, MG 37200-900, Brazil
| | - Pablo Schulman
- Embrapa Rice and Beans, Rodovia GO-462, PO Box 179, Santo Antônio de Goiás, GO 75375-000, Brazil
| | | | - Rafaela Araújo Guimaraes
- Department of Phytopathology, Federal University of Lavras, PO Box 3037, Lavras, MG 37200-900, Brazil
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Andrade PHM, Machado PC, Paula AF, Paganin ACL, Rezende GS, Matheucci E, Carvalho LM, Freire CCM, Cunha AF, Lacava PT. 16S metabarcoding analysis reveals the influence of organic and conventional farming practices on bacterial communities from the rhizospheric of Coffea arabica L. BRAZ J BIOL 2023; 83:e274070. [PMID: 37937628 DOI: 10.1590/1519-6984.274070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 09/18/2023] [Indexed: 11/09/2023] Open
Abstract
Coffea sp. is cultivated in many tropical countries. Brazil has always adopted intensive agricultural practices, but organic coffee farming is an alternative system based on the non-use of agrochemicals and the rational management of soils. Metabarcoding 16S analysis using next-generation sequencing has been developed to identify and compare the diversity of the Coffea arabica L. rhizospheric bacterial community in two farming areas in São Paulo, Brazil. Dourado uses conventional farming, while Ribeirão Corrente uses organic. We found broad taxonomic composition, with sequences from 24 phyla, 55 classes, 61 orders, 146 families, and 337genus. The three most abundant phyla were Proteobacteria (38.27%), Actinobacteria (15.56%), and Acidobacteria (16.10%). In organic farming, the top 3 were the family Sphingomonadaceae, order Rhizobiales, genus Nocardioides, and Gp6. The genus Gp2 and the phylum Candidatus Saccharibacteria were the most abundant OTUs exclusively present in conventional farming. In the organic farming practice, Proteobacteria, Actinobacteria, and Acidobacteria were also present among the exclusive OTUs; we also found OTUs belonging to Bacteroidetes, Firmicutes, and Verrucomicrobia. Our study indicates a positive effect of organic farming on microbial communities. Fertilization may directly affect soil microbiota, suggesting that a large and active microbial community low in functional diversity might not adapt to new climatic conditions. A diverse community could provide better resilience to environmental changes, improving the productivity of this important crop.
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Affiliation(s)
- P H M Andrade
- Universidade Federal de São Carlos - UFSCar, Programa de Pós-graduação em Genética Evolutiva e Biologia Molecular, São Carlos, SP, Brasil
- Universidade Federal de São Carlos - UFSCar, Centro de Ciências Biológicas e da Saúde, Departamento de Morfologia e Patologia, Laboratório de Microbiologia e Biomoléculas, São Carlos, SP, Brasil
| | - P C Machado
- Universidade Federal de São Carlos - UFSCar, Centro de Ciências Biológicas e da Saúde, Departamento de Morfologia e Patologia, Laboratório de Microbiologia e Biomoléculas, São Carlos, SP, Brasil
- Universidade Federal de São Carlos - UFSCar, Programa de Pós-graduação em Biotecnologia, São Carlos, São Paulo, Brasil
| | - A F Paula
- Universidade Federal de São Carlos - UFSCar, Programa de Pós-graduação em Genética Evolutiva e Biologia Molecular, São Carlos, SP, Brasil
- Universidade Federal de São Carlos - UFSCar, Centro de Ciências Biológicas e da Saúde, Departamento de Morfologia e Patologia, Laboratório de Microbiologia e Biomoléculas, São Carlos, SP, Brasil
| | - A C L Paganin
- Universidade Federal de São Carlos - UFSCar, Departamento de Genética e Evolução, Laboratório de Bioquímica e Genética Aplicada, São Carlos, SP, Brasil
| | - G S Rezende
- Universidade Federal de São Carlos - UFSCar, Departamento de Genética e Evolução, Laboratório de Bioquímica e Genética Aplicada, São Carlos, SP, Brasil
| | - E Matheucci
- Universidade Federal de São Carlos - UFSCar, Programa de Pós-graduação em Biotecnologia, São Carlos, São Paulo, Brasil
- DNA Consult, São Carlos, SP, Brasil
| | - L M Carvalho
- Universidade Estadual de Campinas - Unicamp, Instituto de Biologia, Departamento de Genética e Evolução, Laboratório de Genômica e Expressão, Campinas, SP, Brasil
| | - C C M Freire
- Universidade Federal de São Carlos - UFSCar, Departamento de Genética e Evolução, Laboratório de Bioinformática Evolutiva, São Carlos, SP, Brasil
| | - A F Cunha
- Universidade Federal de São Carlos - UFSCar, Programa de Pós-graduação em Biotecnologia, São Carlos, São Paulo, Brasil
- Universidade Federal de São Carlos - UFSCar, Departamento de Genética e Evolução, Laboratório de Bioquímica e Genética Aplicada, São Carlos, SP, Brasil
| | - P T Lacava
- Universidade Federal de São Carlos - UFSCar, Centro de Ciências Biológicas e da Saúde, Departamento de Morfologia e Patologia, Laboratório de Microbiologia e Biomoléculas, São Carlos, SP, Brasil
- Universidade Federal de São Carlos - UFSCar, Programa de Pós-graduação em Biotecnologia, São Carlos, São Paulo, Brasil
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Dimopoulou A, Theologidis I, Varympopi A, Papafotis D, Mermigka G, Tzima A, Panopoulos NJ, Skandalis N. Shifting Perspectives of Translational Research in Bio-Bactericides: Reviewing the Bacillus amyloliquefaciens Paradigm. BIOLOGY 2021; 10:biology10111202. [PMID: 34827195 PMCID: PMC8614995 DOI: 10.3390/biology10111202] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 11/11/2021] [Accepted: 11/15/2021] [Indexed: 11/16/2022]
Abstract
Simple Summary The continuous reduction of approved conventional microbicides, due to health concerns and the development of plant-pathogen resistance, has been urged for the use of safe alternatives in crop protection. Several beneficial bacterial species, termed biological control agents, are currently used in lieu of chemical pesticides. The approach to select such bacterial species and manufacture commercial products has been based on their biocontrol effect under optimal growth conditions, which is far from the real nutrient-limited field conditions of plant niches. It’s important to determine the complex interactions that occur among BCAs, plant host and niche microbiome to fully understand and exploit the potential of biological control agents. Furthermore, it’s crucial to acknowledge the environmental impact of their long-term use. Abstract Bacterial biological control agents (BCAs) have been increasingly used against plant diseases. The traditional approach to manufacturing such commercial products was based on the selection of bacterial species able to produce secondary metabolites that inhibit mainly fungal growth in optimal media. Such species are required to be massively produced and sustain long-term self-storage. The endpoint of this pipeline is large-scale field tests in which BCAs are handled as any other pesticide. Despite recent knowledge of the importance of BCA-host-microbiome interactions to trigger plant defenses and allow colonization, holistic approaches to maximize their potential are still in their infancy. There is a gap in scientific knowledge between experiments in controlled conditions for optimal BCA and pathogen growth and the nutrient-limited field conditions in which they face niche microbiota competition. Moreover, BCAs are considered to be safe by competent authorities and the public, with no side effects to the environment; the OneHealth impact of their application is understudied. This review summarizes the state of the art in BCA research and how current knowledge and new biotechnological tools have impacted BCA development and application. Future challenges, such as their combinational use and ability to ameliorate plant stress are also discussed. Addressing such challenges would establish their long-term use as centerfold agricultural pesticides and plant growth promoters.
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Affiliation(s)
- Anastasia Dimopoulou
- Institute of Molecular Biology and Biotechnology, FORTH, 70013 Heraklion, Greece; (A.D.); (G.M.)
| | - Ioannis Theologidis
- Laboratory of Pesticides’ Toxicology, Benaki Phytopathological Institute, 14561 Athens, Greece;
| | - Adamantia Varympopi
- Enzyme and Microbial Biotechnology Unit, Department of Biology, National and Kapodistrian University of Athens, 15784 Athens, Greece; (A.V.); (D.P.)
| | - Dimitris Papafotis
- Enzyme and Microbial Biotechnology Unit, Department of Biology, National and Kapodistrian University of Athens, 15784 Athens, Greece; (A.V.); (D.P.)
| | - Glykeria Mermigka
- Institute of Molecular Biology and Biotechnology, FORTH, 70013 Heraklion, Greece; (A.D.); (G.M.)
| | - Aliki Tzima
- Laboratory of Plant Pathology, Department of Crop Production, School of Agricultural Production Infrastructure and Environment, Faculty of Crop Science, Agricultural University of Athens, 11855 Athens, Greece;
| | - Nick J. Panopoulos
- Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720, USA;
| | - Nicholas Skandalis
- Health Sciences Campus, Keck School of Medicine, University of Southern California, 1441 Eastlake Ave, Los Angeles, CA 90033, USA
- Correspondence:
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Streptomyces strains modulate dynamics of soil bacterial communities and their efficacy in disease suppression caused by Phytophthora capsici. Sci Rep 2021; 11:9317. [PMID: 33927238 PMCID: PMC8085009 DOI: 10.1038/s41598-021-88495-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 04/13/2021] [Indexed: 11/16/2022] Open
Abstract
The responses of rhizosphere bacterial communities of Streptomyces (SS14 and IT20 stains) treated-pepper plants following inoculation by Phytophthora capsici (PC) was investigated using Illumina MiSeq sequencing. Distinct modulation of the bacteriome composition was found for PC samples with the highest relative abundance (RA) of Chitinophaga (22 ± 0.03%). The RA of several bacterial operational taxonomic units (OTUs) was affected and caused changes in alpha and beta-diversity measures. In IT20, the RA of Cyanobacteria was enriched compared to SS14 (72%) and control samples (47%). Phylotypes belonging to Devosia, Promicromonospora, Kribbella, Microbacterium, Amylocolatopsis, and Pseudomonas genera in the rhizosphere were positively responding against the pathogen. Our findings show that the phosphate solubilizing strain IT20 has higher microbial community responders than the melanin-producing strain SS14. Also, positive interactions were identified by comparing bacterial community profiles between treatments that might allow designing synthetic bio-inoculants to solve agronomic problems in an eco-friendly way.
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Berg G, Kusstatscher P, Abdelfattah A, Cernava T, Smalla K. Microbiome Modulation-Toward a Better Understanding of Plant Microbiome Response to Microbial Inoculants. Front Microbiol 2021; 12:650610. [PMID: 33897663 PMCID: PMC8060476 DOI: 10.3389/fmicb.2021.650610] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 03/19/2021] [Indexed: 12/31/2022] Open
Abstract
Plant-associated microorganisms are involved in important functions related to growth, performance and health of their hosts. Understanding their modes of action is important for the design of promising microbial inoculants for sustainable agriculture. Plant-associated microorganisms are able to interact with their hosts and often exert specific functions toward potential pathogens; the underlying in vitro interactions are well studied. In contrast, in situ effects of inoculants, and especially their impact on the plant indigenous microbiome was mostly neglected so far. Recently, microbiome research has revolutionized our understanding of plants as coevolved holobionts but also of indigenous microbiome-inoculant interactions. Here we disentangle the effects of microbial inoculants on the indigenous plant microbiome and point out the following types of plant microbiome modulations: (i) transient microbiome shifts, (ii) stabilization or increase of microbial diversity, (iii) stabilization or increase of plant microbiome evenness, (iv) restoration of a dysbiosis/compensation or reduction of a pathogen-induced shift, (v) targeted shifts toward plant beneficial members of the indigenous microbiota, and (vi) suppression of potential pathogens. Therefore, we suggest microbiome modulations as novel and efficient mode of action for microbial inoculants that can also be mediated via the plant.
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Affiliation(s)
- Gabriele Berg
- Institute of Environmental Biotechnology, Graz University of Technology, Graz, Austria
| | - Peter Kusstatscher
- Institute of Environmental Biotechnology, Graz University of Technology, Graz, Austria
| | - Ahmed Abdelfattah
- Institute of Environmental Biotechnology, Graz University of Technology, Graz, Austria
| | - Tomislav Cernava
- Institute of Environmental Biotechnology, Graz University of Technology, Graz, Austria
| | - Kornelia Smalla
- Julius Kühn Institute (JKI) Federal Research Centre for Cultivated Plants, Institute for Epidemiology and Pathogen Diagnostics, Braunschweig, Germany
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Vischetti C, Casucci C, De Bernardi A, Monaci E, Tiano L, Marcheggiani F, Ciani M, Comitini F, Marini E, Taskin E, Puglisi E. Sub-Lethal Effects of Pesticides on the DNA of Soil Organisms as Early Ecotoxicological Biomarkers. Front Microbiol 2020; 11:1892. [PMID: 33013727 PMCID: PMC7461845 DOI: 10.3389/fmicb.2020.01892] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 07/20/2020] [Indexed: 01/13/2023] Open
Abstract
This review describes the researches performed in the last years to assess the impact of pesticide sub-lethal doses on soil microorganisms and non-target organisms in agricultural soil ecosystems. The overview was developed through the careful description and a critical analysis of three methodologies based on culture-independent approaches involving DNA extraction and sequencing (denaturing gradient gel electrophoresis, DGGE; next-generation sequencing, NGS) to characterize the microbial population and DNA damage assessment (comet assay) to determine the effect on soil invertebrates. The examination of the related published articles showed a continuous improvement of the possibility to detect the detrimental effect of the pesticides on soil microorganisms and non-target organisms at sub-lethal doses, i.e., doses which have no lethal effect on the organisms. Considering the overall critical discussion on microbial soil monitoring in the function of pesticide treatments, we can confirm the usefulness of PCR-DGGE as a screening technique to assess the genetic diversity of microbial communities. Nowadays, DGGE remains a preliminary technique to highlight rapidly the main differences in microbial community composition, which is able to give further information if coupled with culture-dependent microbiological approaches, while thorough assessments must be gained by high-throughput techniques such as NGS. The comet assay represents an elective technique for assessing genotoxicity in environmental biomonitoring, being mature after decades of implementation and widely used worldwide for its direct, simple, and affordable implementation. Nonetheless, in order to promote the consistency and reliability of results, regulatory bodies should provide guidelines on the optimal use of this tool, strongly indicating the most reliable indicators of DNA damage. This review may help the European Regulation Authority in deriving new ecotoxicological endpoints to be included in the Registration Procedure of new pesticides.
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Affiliation(s)
- Costantino Vischetti
- Department of Agricultural, Food and Environmental Sciences, Marche Polytechnic University, Ancona, Italy
| | - Cristiano Casucci
- Department of Agricultural, Food and Environmental Sciences, Marche Polytechnic University, Ancona, Italy
| | - Arianna De Bernardi
- Department of Agricultural, Food and Environmental Sciences, Marche Polytechnic University, Ancona, Italy
| | - Elga Monaci
- Department of Agricultural, Food and Environmental Sciences, Marche Polytechnic University, Ancona, Italy
| | - Luca Tiano
- Department of Life and Environmental Sciences, Marche Polytechnic University, Ancona, Italy
| | - Fabio Marcheggiani
- Department of Life and Environmental Sciences, Marche Polytechnic University, Ancona, Italy
| | - Maurizio Ciani
- Department of Life and Environmental Sciences, Marche Polytechnic University, Ancona, Italy
| | - Francesca Comitini
- Department of Life and Environmental Sciences, Marche Polytechnic University, Ancona, Italy
| | - Enrica Marini
- Department of Life and Environmental Sciences, Marche Polytechnic University, Ancona, Italy
| | - Eren Taskin
- Department for Sustainable Food Process, Faculty of Agriculture, Food and Environmental Sciences, Catholic University of Sacred Heart, Piacenza, Italy
| | - Edoardo Puglisi
- Department for Sustainable Food Process, Faculty of Agriculture, Food and Environmental Sciences, Catholic University of Sacred Heart, Piacenza, Italy
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Xia X, Ran C, Ye X, Li G, Kan J, Zheng J. Monitoring of the bacterial communities of bamboo shoots (Dendrocalamus latiflorus) during pickling process. Int J Food Sci Technol 2017. [DOI: 10.1111/ijfs.13374] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Xuejuan Xia
- College of Food Science; Southwest University; Chongqing 400715 China
| | - Chunxia Ran
- Department of Medical Technology; Chongqing Three Gorges Medical College; Chongqing 404120 China
| | - Xiujuan Ye
- College of Food Science; Southwest University; Chongqing 400715 China
| | - Guannan Li
- College of Biotechnology; Southwest University; Chongqing 400715 China
| | - Jianquan Kan
- College of Food Science; Southwest University; Chongqing 400715 China
| | - Jiong Zheng
- College of Food Science; Southwest University; Chongqing 400715 China
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Zheng Y, Jiao X, Chen F, Wang X, Wang M. Expiration Date Prediction of Biocontrol Agent Prepared with Bacillus subtilis B579 Using the Accelerated Aging Method. Pol J Microbiol 2017; 65:461-464. [PMID: 28735330 DOI: 10.5604/17331331.1227672] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The expiration date of biopesticidal products is an essential feature of their use and storage. In the present work, the expiration date of biocontrol agent was predicted using the accelerated aging method. The available bacteria in Bacillus subtilis B579 biocontrol agent were 3.7 ± 0.2 × 1011 CFU/g. It is calculated that the expiration date of the agent was about 17 months at 25°C. During this period, the available bacteria retained more than 90% of the value in the initial product. Thus, this work suggests the expiration date of biocontrol agents composed with spores could be estimated using the accelerated aging method.
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Affiliation(s)
- Yu Zheng
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Xiaoyang Jiao
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Fang Chen
- School of Pharmaceutical, Liaocheng University, Liaocheng, Shandong, China
| | - Xuelian Wang
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Min Wang
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China
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Liu A, Peng Z, Zou L, Zhou K, Ao X, He L, Chen S, Liu S. The effects of lactic acid-based spray washing on bacterial profile and quality of chicken carcasses. Food Control 2016. [DOI: 10.1016/j.foodcont.2015.09.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Szoboszlay M, White-Monsant A, Moe LA. The Effect of Root Exudate 7,4'-Dihydroxyflavone and Naringenin on Soil Bacterial Community Structure. PLoS One 2016; 11:e0146555. [PMID: 26752410 PMCID: PMC4709137 DOI: 10.1371/journal.pone.0146555] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2015] [Accepted: 12/19/2015] [Indexed: 12/14/2022] Open
Abstract
Our goal was to investigate how root exudate flavonoids influence the soil bacterial community structure and to identify members of the community that change their relative abundance in response to flavonoid exudation. Using a model system that approximates flavonoid exudation of Medicago sativa roots, we treated a soil with 7,4'-dihydroxyflavone and naringenin in two separate experiments using three different rates: medium (equivalent to the exudation rate of 7,4'-dihydroxyflavone from M. sativa seedlings), high (10× the medium rate), and low (0.1× the medium rate). Controls received no flavonoid. Soil samples were subjected to ATP assays and 16S rRNA gene amplicon sequencing. The flavonoid treatments caused no significant change in the soil ATP content. With the high 7,4'-dihydroxyflavone treatment rate, operational taxonomic units (OTUs) classified as Acidobacteria subdivision 4 increased in relative abundance compared with the control samples, whereas OTUs classified as Gaiellales, Nocardioidaceae, and Thermomonosporaceae were more prevalent in the control. The naringenin treatments did not cause significant changes in the soil bacterial community structure. Our results suggest that the root exudate flavonoid 7,4'-dihydroxyflavone can interact with a diverse range of soil bacteria and may have other functions in the rhizosphere in addition to nod gene induction in legume-rhizobia symbiosis.
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Affiliation(s)
- Márton Szoboszlay
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, Kentucky, United States of America
| | - Alison White-Monsant
- Department of Animal, Plant and Soil Science, Centre for AgriBioscience, La Trobe University, Melbourne, Australia
| | - Luke A. Moe
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, Kentucky, United States of America
- * E-mail:
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