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Graziosi S, Puliga F, Iotti M, Amicucci A, Zambonelli A. In vitro interactions between Bradyrhizobium spp. and Tuber magnatum mycelium. ENVIRONMENTAL MICROBIOLOGY REPORTS 2024; 16:e13271. [PMID: 38692852 PMCID: PMC11062863 DOI: 10.1111/1758-2229.13271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 04/06/2024] [Indexed: 05/03/2024]
Abstract
Tuber magnatum is the most expensive truffle, but its large-scale cultivation is still a challenge compared to other valuable Tuber species. T. magnatum mycelium has never been grown profitably until now, which has led to difficulties to studying it in vitro. This study describes beneficial interactions between T. magnatum mycelium and never before described bradyrhizobia, which allows the in vitro growth of T. magnatum mycelium. Three T. magnatum strains were co-isolated on modified Woody Plant Medium (mWPM) with aerobic bacteria and characterised through microscopic observations. The difficulties of growing alone both partners, bacteria and T. magnatum mycelium, on mWPM demonstrated the reciprocal dependency. Three bacterial isolates for each T. magnatum strain were obtained and molecularly characterised by sequencing the 16S rRNA, glnII, recA and nifH genes. Phylogenetic analyses showed that all nine bacterial strains were distributed among five subclades included in a new monophyletic lineage belonging to the Bradyrhizobium genus within the Bradyrhizobium jicamae supergroup. The nifH genes were detected in all bacterial isolates, suggesting nitrogen-fixing capacities. This is the first report of consistent T. magnatum mycelium growth in vitro conditions. It has important implications for the development of new technologies in white truffle cultivation and for further studies on T. magnatum biology and genetics.
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Affiliation(s)
- Simone Graziosi
- Department of Agricultural and Food SciencesUniversity of BolognaBolognaItaly
| | - Federico Puliga
- Department of Agricultural and Food SciencesUniversity of BolognaBolognaItaly
| | - Mirco Iotti
- Department of Life, Health and Environmental ScienceUniversity of L'AquilaL'AquilaItaly
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Fan Y, Sun S, He S. Iron plaque formation and its effect on key elements cycling in constructed wetlands: Functions and outlooks. WATER RESEARCH 2023; 235:119837. [PMID: 36905735 DOI: 10.1016/j.watres.2023.119837] [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: 11/14/2022] [Revised: 02/13/2023] [Accepted: 03/05/2023] [Indexed: 06/18/2023]
Abstract
Ecological restoration of wetland plants has emerged as an environmentally-friendly and less carbon footprint method for treating secondary effluent wastewater. Root iron plaque (IP) is located at the important ecological niches in constructed wetlands (CWs) ecosystem and is the critical micro-zone for pollutants migration and transformation. Root IP can affect the chemical behaviors and bioavailability of key elements (C, N, P) since its formation/dissolution is a dynamic equilibrium process jointly influenced by rhizosphere habitats. However, as an efficient approach to further explore the mechanism of pollutant removal in CWs, the dynamic formation of root IP and its function have not been fully studied, especially in substrate-enhanced CWs. This article concentrates on the biogeochemical processes between Fe cycling involved in root IP with carbon turnover, nitrogen transformation, and phosphorus availability in CWs rhizosphere. As IP has the potential to enhance pollutant removal by being regulated and managed, we summarized the critical factors affecting the IP formation from the perspective of wetland design and operation, as well as emphasizing the heterogeneity of rhizosphere redox and the role of key microbes in nutrient cycling. Subsequently, interactions between redox-controlled root IP and biogeochemical elements (C, N, P) are emphatically discussed. Additionally, the effects of IP on emerging contaminants and heavy metals in CWs rhizosphere are assessed. Finally, major challenges and outlooks for future research in regards to root IP are proposed. It is expected that this review can provide a new perspective for the efficient removal of target pollutants in CWs.
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Affiliation(s)
- Yuanyuan Fan
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Shanshan Sun
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Shengbing He
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; Shanghai Engineering Research Center of Landscape Water Environment, Shanghai 200031, China.
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Zhao Y, Guan D, Liu X, Gao GF, Meng F, Liu B, Xing P, Jiang X, Ma M, Cao F, Li L, Li J. Profound Change in Soil Microbial Assembly Process and Co-occurrence Pattern in Co-inoculation of Bradyrhizobium japonicum 5038 and Bacillus aryabhattai MB35-5 on Soybean. Front Microbiol 2022; 13:846359. [PMID: 35369449 PMCID: PMC8972127 DOI: 10.3389/fmicb.2022.846359] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Accepted: 02/18/2022] [Indexed: 12/04/2022] Open
Abstract
Rhizosphere microbial communities are vital for plant growth and soil sustainability; however, the composition of rhizobacterial communities, especially the assembly process and co-occurrence pattern among microbiota after the inoculation of some beneficial bacteria, remains considerably unclear. In this study, we investigated the structure of rhizomicrobial communities, their assembly process, and interactions contrasting when Bradyrhizobium japonicum 5038 and Bacillus aryabhattai MB35-5 are co-inoculated or Bradyrhizobium japonicum 5038 mono-inoculated in black and cinnamon soils of soybean fields. The obtained results indicated that the Chao and Shannon indices were all higher in cinnamon soil than that in black soil. In black soil, the co-inoculation increased the Shannon indices of bacteria comparing with that of the mono-inoculation. In cinnamon soil, the co-inoculation decreased the Chao indices of fungi comparing with that of mono-inoculation. Compared with the mono-inoculation, the interactions of microorganisms of co-inoculation in the co-occurrence pattern increased in complexity, and the nodes and edges of co-inoculation increased by 10.94, 40.18 and 4.82, 16.91% for bacteria and fungi, respectively. The co-inoculation of Bradyrhizobium japonicum 5038 and Bacillus aryabhattai MB35-5 increased the contribution of stochastic processes comparing with Bradyrhizobium japonicum 5038 inoculation in the assembly process of soil microorganisms, and owing to the limitation of species diffusion might restrict the direction of pathogenic microorganism movement. These findings support the feasibility of rebuilding the rhizosphere microbial system via specific microbial strain inoculation and provide evidence that the co-inoculation of Bradyrhizobium japonicum 5038 and Bacillus aryabhattai MB35-5 can be adopted as an excellent compound rhizobia agent resource for the sustainable development of agriculture.
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Affiliation(s)
- Yubin Zhao
- Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Dawei Guan
- Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Xu Liu
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China
| | - Gui-Feng Gao
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China
| | - Fangang Meng
- Soybean Research Institute, Jilin Academy of Agricultural Sciences, Jilin, China
| | - Bingqiang Liu
- Institute of Cereal and Oil Crops, Hebei Academy of Agricultural and Forestry Sciences, Hebei, China
| | - Pengfei Xing
- Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Xin Jiang
- Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Mingchao Ma
- Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Fengming Cao
- Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Li Li
- Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Jun Li
- Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, China
- *Correspondence: Jun Li,
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Pérez-Giménez J, Iturralde ET, Torres Tejerizo G, Quelas JI, Krol E, Borassi C, Becker A, Estevez JM, Lodeiro AR. A Stringent-Response-Defective Bradyrhizobium diazoefficiens Strain Does Not Activate the Type 3 Secretion System, Elicits an Early Plant Defense Response, and Circumvents NH 4NO 3-Induced Inhibition of Nodulation. Appl Environ Microbiol 2021; 87:e02989-20. [PMID: 33608284 PMCID: PMC8091029 DOI: 10.1128/aem.02989-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 02/08/2021] [Indexed: 12/30/2022] Open
Abstract
When subjected to nutritional stress, bacteria modify their amino acid metabolism and cell division activities by means of the stringent response, which is controlled by the Rsh protein in alphaproteobacteria. An important group of alphaproteobacteria are the rhizobia, which fix atmospheric N2 in symbiosis with legume plants. Although nutritional stress is common for rhizobia while infecting legume roots, the stringent response has scarcely been studied in this group of soil bacteria. In this report, we obtained a mutant with a kanamycin resistance insertion in the rsh gene of Bradyrhizobium diazoefficiens, the N2-fixing symbiont of soybean. This mutant was defective for type 3 secretion system induction, plant defense suppression at early root infection, and nodulation competition. Furthermore, the mutant produced smaller nodules, although with normal morphology, which led to lower plant biomass production. Soybean (Glycine max) genes GmRIC1 and GmRIC2, involved in autoregulation of nodulation, were upregulated in plants inoculated with the mutant under the N-free condition. In addition, when plants were inoculated in the presence of 10 mM NH4NO3, the mutant produced nodules containing bacteroids, and GmRIC1 and GmRIC2 were downregulated. The rsh mutant released more auxin to the culture supernatant than the wild type, which might in part explain its symbiotic behavior in the presence of combined N. These results indicate that the B. diazoefficiens stringent response integrates into the plant defense suppression and regulation of nodulation circuits in soybean, perhaps mediated by the type 3 secretion system.IMPORTANCE The symbiotic N2 fixation carried out between prokaryotic rhizobia and legume plants performs a substantial contribution to the N cycle in the biosphere. This symbiotic association is initiated when rhizobia infect and penetrate the root hairs, which is followed by the growth and development of root nodules, within which the infective rhizobia are established and protected. Thus, the nodule environment allows the expression and function of the enzyme complex that catalyzes N2 fixation. However, during early infection, the rhizobia find a harsh environment while penetrating the root hairs. To cope with this nuisance, the rhizobia mount a stress response known as the stringent response. In turn, the plant regulates nodulation in response to the presence of alternative sources of combined N in the surrounding medium. Control of these processes is crucial for a successful symbiosis, and here we show how the rhizobial stringent response may modulate plant defense suppression and the networks of regulation of nodulation.
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Affiliation(s)
- Julieta Pérez-Giménez
- IBBM, Facultad de Ciencias Exactas, CCT-La Plata CONICET, Universidad Nacional de La Plata, La Plata, Argentina
| | - Esteban T Iturralde
- IBBM, Facultad de Ciencias Exactas, CCT-La Plata CONICET, Universidad Nacional de La Plata, La Plata, Argentina
| | - Gonzalo Torres Tejerizo
- IBBM, Facultad de Ciencias Exactas, CCT-La Plata CONICET, Universidad Nacional de La Plata, La Plata, Argentina
| | - Juan Ignacio Quelas
- IBBM, Facultad de Ciencias Exactas, CCT-La Plata CONICET, Universidad Nacional de La Plata, La Plata, Argentina
| | - Elizaveta Krol
- Center for Synthetic Microbiology (SYNMIKRO), Department of Biology, Philipps-Universität Marburg, Marburg, Germany
| | - Cecilia Borassi
- Fundación Instituto Leloir, Instituto de Investigaciones Bioquímicas de Buenos Aires-CONICET, Buenos Aires, Argentina
| | - Anke Becker
- Center for Synthetic Microbiology (SYNMIKRO), Department of Biology, Philipps-Universität Marburg, Marburg, Germany
| | - José M Estevez
- Fundación Instituto Leloir, Instituto de Investigaciones Bioquímicas de Buenos Aires-CONICET, Buenos Aires, Argentina
- Centro de Biotecnología Vegetal, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
- Millennium Institute for Integrative Biology (iBio), Santiago, Chile
| | - Aníbal R Lodeiro
- IBBM, Facultad de Ciencias Exactas, CCT-La Plata CONICET, Universidad Nacional de La Plata, La Plata, Argentina
- Laboratorio de Genética, Facultad de Ciencias Agrarias y Forestales, Universidad Nacional de La Plata, La Plata, Argentina
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