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Ali R, Chaluvadi SR, Wang X, Hazzouri KM, Sudalaimuthuasari N, Rafi M, Al-Nuaimi M, Sasi S, Antepenko E, Bennetzen JL, Amiri KMA. Microbiome properties in the root nodules of Prosopis cineraria, a leguminous desert tree. Microbiol Spectr 2024:e0361723. [PMID: 38624222 DOI: 10.1128/spectrum.03617-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 03/14/2024] [Indexed: 04/17/2024] Open
Abstract
We conducted a comprehensive analysis of the total microbiome and transcriptionally active microbiome communities in the roots and root nodules of Prosopis cineraria, an important leguminous tree in arid regions of many Asian countries. Mature P. cineraria trees growing in the desert did not exhibit any detected root nodules. However, we observed root nodules on the roots of P. cineraria growing on a desert farm and on young plants growing in a growth chamber, when inoculated with rhizosphere soil, including with rhizosphere soil from near desert tree roots that had no nodules. Compared to nearby soil, non-nodulated roots were enriched with Actinobacteria (e.g., Actinophytocola sp.), whereas root nodules sampled from the desert farm and growth chamber had abundant Alphaproteobacteria (e.g., Ensifer sp.). These nodules yielded many microbes in addition to such nitrogen-fixing bacteria as Ensifer and Sinorhizobium species. Significant differences exist in the composition and abundance of microbial isolates between the nodule surface and the nodule endosphere. Shotgun metagenome analysis of nodule endospheres revealed that the root nodules comprised over 90% bacterial DNA, whereas metatranscriptome analysis showed that the plant produces vastly more transcripts than the microbes in these nodules. Control inoculations demonstrated that four out of six Rhizobium, Agrobacterium, or Ensifer isolates purified from P. cineraria nodules produced nodules in the roots of P. cineraria seedlings under greenhouse conditions. The best nodulation was achieved when seedlings were inoculated with a mixture of those bacterial strains. Though root nodulation could be achieved under water stress conditions, nodule number and nodule biomass increased with copious water availability. .IMPORTANCEMicrobial communities were investigated in roots and root nodules of Prosopis cineraria, a leguminous tree species in arid Asian regions that is responsible for exceptionally important contributions to soil fertility in these dramatically dry locations. Soil removed from regions near nodule-free roots on these mature plants contained an abundance of bacteria with the genetic ability to generate nodules and fix nitrogen but did not normally nodulate in their native rhizosphere environment, suggesting a very different co-evolved relationship than that observed for herbaceous legumes. The relative over-expression of the low-gene-density plant DNA compared to the bacterial DNA in the nodules was also unexpected, indicating a very powerful induction of host genetic contributions within the nodule. Finally, the water dependence of nodulation in inoculated seedlings suggested a possible link between early seedling growth (before a deep root system can be developed) and the early development of nitrogen-fixing capability.
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Affiliation(s)
- Rashid Ali
- Mitrix Bio., Inc., Farmington, Connecticut, USA
| | | | - Xuewen Wang
- Department of Genetics, University of Georgia, Athens, Georgia, USA
| | - Khaled M Hazzouri
- Khalifa Center for Genetic Engineering and Biotechnology, United Arab Emirates University, Al-Ain, UAE
| | | | - Mohammed Rafi
- Khalifa Center for Genetic Engineering and Biotechnology, United Arab Emirates University, Al-Ain, UAE
| | - Mariam Al-Nuaimi
- Khalifa Center for Genetic Engineering and Biotechnology, United Arab Emirates University, Al-Ain, UAE
| | - Shina Sasi
- Khalifa Center for Genetic Engineering and Biotechnology, United Arab Emirates University, Al-Ain, UAE
| | - Eric Antepenko
- Department of Genetics, University of Georgia, Athens, Georgia, USA
| | | | - Khaled M A Amiri
- Khalifa Center for Genetic Engineering and Biotechnology, United Arab Emirates University, Al-Ain, UAE
- Department of Biology, College of Science, United Arab Emirates University, Al-Ain, UAE
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Hnini M, El Attar I, Taha K, Aurag J. Genetic diversity, symbiotic efficiency, stress tolerance, and plant growth promotion traits of rhizobia nodulating Vachellia tortilis subsp. raddiana growing in dryland soils in southern Morocco. Syst Appl Microbiol 2023; 46:126434. [PMID: 37210974 DOI: 10.1016/j.syapm.2023.126434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 05/08/2023] [Accepted: 05/11/2023] [Indexed: 05/23/2023]
Abstract
In the present study, we analyzed the genetic diversity, phylogenetic relationships, stress tolerance, phytobeneficial traits, and symbiotic characteristics of rhizobial strains isolated from root nodules of Vachellia tortilis subsp. raddiana grown in soils collected in the extreme Southwest of the Anti-Atlas Mountains in Morocco. Subsequent to Rep-PCR fingerprinting, 16S rDNA gene sequencing of 15 representative strains showed that all of them belong to the genus Ensifer. Phylogenetic analysis and concatenation of the housekeeping genes gyrB, rpoB, recA, and dnaK revealed that the entire collection (except strain LMR678) shared 99.08 % to 99.92% similarity with Ensifer sp. USDA 257 and 96.92% to 98.79% with Sinorhizobium BJ1. Phylogenetic analysis of nodC and nodA sequences showed that all strains but one (LMR678) formed a phylogenetic group with the type strain "E. aridi" LMR001T (similarity over 98%). Moreover, it was relevant that most strains belong to the symbiovar vachelliae. In vitro tests revealed that five strains produced IAA, four solubilized inorganic phosphate, and one produced siderophores. All strains showed tolerance to NaCl concentrations ranging from 2 to 12% and grew at up to 10% of PEG6000. A greenhouse plant inoculation test conducted during five months demonstrated that most rhizobial strains were infective and efficient. Strains LMR688, LMR692, and LMR687 exhibited high relative symbiotic efficiency values (respectively 231.6 %, 171.96 %, and 140.84 %). These strains could be considered as the most suitable candidates for inoculation of V. t. subsp. raddiana, to be used as a pioneer plant for restoring arid soils threatened with desertification.
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Affiliation(s)
- Mohamed Hnini
- Microbiology and Molecular Biology Team, Center of Plant and Microbial Biotechnology, Biodiversity and Environment, Faculty of Sciences, Mohammed V University in Rabat, Avenue Ibn Battouta, BP 1014, 10000 Rabat, Morocco
| | - Imane El Attar
- Microbiology and Molecular Biology Team, Center of Plant and Microbial Biotechnology, Biodiversity and Environment, Faculty of Sciences, Mohammed V University in Rabat, Avenue Ibn Battouta, BP 1014, 10000 Rabat, Morocco
| | - Kaoutar Taha
- Microbiology and Molecular Biology Team, Center of Plant and Microbial Biotechnology, Biodiversity and Environment, Faculty of Sciences, Mohammed V University in Rabat, Avenue Ibn Battouta, BP 1014, 10000 Rabat, Morocco
| | - Jamal Aurag
- Microbiology and Molecular Biology Team, Center of Plant and Microbial Biotechnology, Biodiversity and Environment, Faculty of Sciences, Mohammed V University in Rabat, Avenue Ibn Battouta, BP 1014, 10000 Rabat, Morocco.
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Ramírez V, Baez A, López P, Bustillos R, Villalobos MÁ, Carreño R, Contreras JL, Muñoz-Rojas J, Fuentes LE, Martínez J, Munive JA. Chromium Hyper-Tolerant Bacillus sp. MH778713 Assists Phytoremediation of Heavy Metals by Mesquite Trees ( Prosopis laevigata). Front Microbiol 2019; 10:1833. [PMID: 31456770 PMCID: PMC6700308 DOI: 10.3389/fmicb.2019.01833] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 07/25/2019] [Indexed: 12/04/2022] Open
Abstract
Heavy metal accumulation in mesquite trees (Prosopis laevigata) growing in aluminum, titanium, chromium and zirconium-polluted soils of a semi-arid region in Mexico was investigated using wavelength dispersive X-ray fluorescence analysis. The results showed that P. laevigata trees can hyper accumulate up to 4100 mg/kg of Al, 14000 mg/kg of Fe, 1600 mg/kg of Ti, 2500 mg/kg of Zn, but not chromium, regarding high chromium concentrations found in soils (435 mg/kg). Since plant-associated microorganism can modulate phytoremediation efficiency, the biodiversity of P. laevigata associated bacteria was studied. Eighty-eight isolates from P. laevigata nodules were obtained; all isolates tolerated high concentrations of Al, Fe, Zn and Cr in vitro. The top-six chromium tolerant strains were identified by 16S rRNA sequence analysis as belonging to genus Bacillus. Bacillus sp. MH778713, close to Bacillus cereus group, showed to be the most resistant strain, tolerating up to 15000 mg/L Cr (VI) and 10000 mg/L of Al. Regarding the bioaccumulation traits, Bacillus sp. MH778713 accumulated up to 100 mg Cr(VI)/g of cells when it was exposed to 1474 mg/L of Cr VI. To assess Bacillus sp. MH778713 ability to assist Prosopis laevigata phytoremediation; twenty plants were inoculated or non-inoculated with Bacillus sp. MH778713 and grown in nitrogen-free Jensen's medium added with 0, 10 and 25 mg/L of Cr(VI). Only plants inoculated with Bacillus sp. grew in the presence of chromium showing the ability of this strain to assist chromium phytoremediation. P. laevigata and Bacillus spp. may be considered as good candidates for soil restoration of arid and semiarid sites contaminated with heavy metals.
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Affiliation(s)
- Verónica Ramírez
- Centro de Investigaciones en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Antonino Baez
- Centro de Investigaciones en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Primavera López
- Centro de Investigaciones en Dispositivos Semiconductores, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Rocío Bustillos
- Centro de Investigaciones en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Miguel Ángel Villalobos
- Centro de Investigación en Biotecnología Aplicada, Instituto Politécnico Nacional, Tlaxcala, Mexico
| | - Ricardo Carreño
- Centro de Investigaciones en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - José Luis Contreras
- Facultad de Arquitectura, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Jesús Muñoz-Rojas
- Centro de Investigaciones en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Luis Ernesto Fuentes
- Centro de Investigaciones en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Javier Martínez
- Centro de Investigaciones en Dispositivos Semiconductores, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - José Antonio Munive
- Centro de Investigaciones en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
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Mahdhi M, Houidheg N, Mahmoudi N, Msaadek A, Rejili M, Mars M. Characterization of Rhizobial Bacteria Nodulating Astragalus corrugatus and Hippocrepis areolata in Tunisian Arid Soils. Pol J Microbiol 2018; 65:331-339. [PMID: 29334057 DOI: 10.5604/17331331.1215612] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Fifty seven bacterial isolates from root nodules of two spontaneous legumes (Astragalus corrugatus and Hippocrepis areolata) growing in the arid areas of Tunisia were characterized by phenotypic features, 16S rDNA PCR-RFLP and 16S rRNA gene sequencing. Phenotypically, our results indicate that A. corrugatus and H. areolata isolates showed heterogenic responses to the different phenotypic features. All isolates were acid producers, fast growers and all of them used different compounds as sole carbon and nitrogen source. The majority of isolate grew at pHs between 6 and 9, at temperatures up to 40°C and tolerated 3% NaCl concentrations. Phylogenetically, the new isolates were affiliated to four genera Sinorhizobium, Rhizobium, Mesorhizobium and Agrobacterium. About 73% of the isolates were species within the genera Sinorhizobium and Rhizobium. The isolates which failed to nodulate their host plants of origin were associated to Agrobacterium genus (three isolates).
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Affiliation(s)
- Mosbah Mahdhi
- Center for Environmental Research and Studies, Jazan University, Jazan, Kingdom of Saudi Arabia
| | - Nadia Houidheg
- Research Unit Biodiversity and Valorization of Arid Areas, Bioressources (BVBAA), Faculty of Sciences, Gabès University, Erriadh-Zrig, Gabès, Tunisia
| | - Neji Mahmoudi
- Research Unit Biodiversity and Valorization of Arid Areas, Bioressources (BVBAA), Faculty of Sciences, Gabès University, Erriadh-Zrig, Gabès, Tunisia
| | - Abdelhakim Msaadek
- Research Unit Biodiversity and Valorization of Arid Areas, Bioressources (BVBAA), Faculty of Sciences, Gabès University, Erriadh-Zrig, Gabès, Tunisia
| | - Mokhtar Rejili
- Research Unit Biodiversity and Valorization of Arid Areas, Bioressources (BVBAA), Faculty of Sciences, Gabès University, Erriadh-Zrig, Gabès, Tunisia
| | - Mohamed Mars
- Research Unit Biodiversity and Valorization of Arid Areas, Bioressources (BVBAA), Faculty of Sciences, Gabès University, Erriadh-Zrig, Gabès, Tunisia
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Carro L, Nouioui I. Taxonomy and systematics of plant probiotic bacteria in the genomic era. AIMS Microbiol 2017; 3:383-412. [PMID: 31294168 PMCID: PMC6604993 DOI: 10.3934/microbiol.2017.3.383] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 05/22/2017] [Indexed: 12/20/2022] Open
Abstract
Recent decades have predicted significant changes within our concept of plant endophytes, from only a small number specific microorganisms being able to colonize plant tissues, to whole communities that live and interact with their hosts and each other. Many of these microorganisms are responsible for health status of the plant, and have become known in recent years as plant probiotics. Contrary to human probiotics, they belong to many different phyla and have usually had each genus analysed independently, which has resulted in lack of a complete taxonomic analysis as a group. This review scrutinizes the plant probiotic concept, and the taxonomic status of plant probiotic bacteria, based on both traditional and more recent approaches. Phylogenomic studies and genes with implications in plant-beneficial effects are discussed. This report covers some representative probiotic bacteria of the phylum Proteobacteria, Actinobacteria, Firmicutes and Bacteroidetes, but also includes minor representatives and less studied groups within these phyla which have been identified as plant probiotics.
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Affiliation(s)
- Lorena Carro
- School of Biology, Newcastle University, Newcastle upon Tyne, UK
| | - Imen Nouioui
- School of Biology, Newcastle University, Newcastle upon Tyne, UK
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Andrews M, Andrews ME. Specificity in Legume-Rhizobia Symbioses. Int J Mol Sci 2017; 18:E705. [PMID: 28346361 PMCID: PMC5412291 DOI: 10.3390/ijms18040705] [Citation(s) in RCA: 134] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2017] [Revised: 03/19/2017] [Accepted: 03/21/2017] [Indexed: 11/24/2022] Open
Abstract
Most species in the Leguminosae (legume family) can fix atmospheric nitrogen (N₂) via symbiotic bacteria (rhizobia) in root nodules. Here, the literature on legume-rhizobia symbioses in field soils was reviewed and genotypically characterised rhizobia related to the taxonomy of the legumes from which they were isolated. The Leguminosae was divided into three sub-families, the Caesalpinioideae, Mimosoideae and Papilionoideae. Bradyrhizobium spp. were the exclusive rhizobial symbionts of species in the Caesalpinioideae, but data are limited. Generally, a range of rhizobia genera nodulated legume species across the two Mimosoideae tribes Ingeae and Mimoseae, but Mimosa spp. show specificity towards Burkholderia in central and southern Brazil, Rhizobium/Ensifer in central Mexico and Cupriavidus in southern Uruguay. These specific symbioses are likely to be at least in part related to the relative occurrence of the potential symbionts in soils of the different regions. Generally, Papilionoideae species were promiscuous in relation to rhizobial symbionts, but specificity for rhizobial genus appears to hold at the tribe level for the Fabeae (Rhizobium), the genus level for Cytisus (Bradyrhizobium), Lupinus (Bradyrhizobium) and the New Zealand native Sophora spp. (Mesorhizobium) and species level for Cicer arietinum (Mesorhizobium), Listia bainesii (Methylobacterium) and Listia angolensis (Microvirga). Specificity for rhizobial species/symbiovar appears to hold for Galega officinalis (Neorhizobium galegeae sv. officinalis), Galega orientalis (Neorhizobium galegeae sv. orientalis), Hedysarum coronarium (Rhizobium sullae), Medicago laciniata (Ensifer meliloti sv. medicaginis), Medicago rigiduloides (Ensifer meliloti sv. rigiduloides) and Trifolium ambiguum (Rhizobium leguminosarum sv. trifolii). Lateral gene transfer of specific symbiosis genes within rhizobial genera is an important mechanism allowing legumes to form symbioses with rhizobia adapted to particular soils. Strain-specific legume rhizobia symbioses can develop in particular habitats.
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Affiliation(s)
- Mitchell Andrews
- Faculty of Agriculture and Life Sciences, Lincoln University, PO Box 84, Lincoln 7647, New Zealand.
| | - Morag E Andrews
- Faculty of Agriculture and Life Sciences, Lincoln University, PO Box 84, Lincoln 7647, New Zealand.
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Mhamdi R, Ardley J, Tian R, Seshadri R, Reddy T, Pati A, Woyke T, Markowitz V, Ivanova N, Kyrpides N, Reeve W. High-quality permanent draft genome sequence of Ensifer meliloti strain 4H41, an effective salt- and drought-tolerant microsymbiont of Phaseolus vulgaris. Stand Genomic Sci 2015; 10:34. [PMID: 26380038 PMCID: PMC4571125 DOI: 10.1186/s40793-015-0005-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 04/15/2015] [Indexed: 11/10/2022] Open
Abstract
Ensifer meliloti 4H41 is an aerobic, motile, Gram-negative, non-spore-forming rod that can exist as a soil saprophyte or as a legume microsymbiont of common bean (Phaseolus vulgaris). Strain 4H41 was isolated in 2002 from root nodules of P. vulgaris grown in South Tunisia from the oasis of Rjim-Maatoug. Strain 4H41 is salt- and drought-tolerant and highly effective at fixing nitrogen with P. vulgaris. Here we describe the features of E. meliloti 4H41, together with genome sequence information and its annotation. The 6,795,637 bp high-quality permanent draft genome is arranged into 47 scaffolds of 47 contigs containing 6,350 protein-coding genes and 72 RNA-only encoding genes, and is one of the rhizobial genomes sequenced as part of the DOE Joint Genome Institute 2010 Genomic Encyclopedia for Bacteria and Archaea-Root Nodule Bacteria (GEBA-RNB) project proposal.
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Affiliation(s)
- Ridha Mhamdi
- Laboratory of Legumes, Centre of Biotechnology of Borj-Cedria, BP 901, Hammam-Lif, 2050 Tunisia
| | - Julie Ardley
- Centre for Rhizobium Studies, Murdoch University, Murdoch, WA Australia
| | - Rui Tian
- Centre for Rhizobium Studies, Murdoch University, Murdoch, WA Australia
| | | | - T.B.K. Reddy
- DOE Joint Genome Institute, Walnut Creek, CA USA
| | - Amrita Pati
- DOE Joint Genome Institute, Walnut Creek, CA USA
| | - Tanja Woyke
- DOE Joint Genome Institute, Walnut Creek, CA USA
| | - Victor Markowitz
- Biological Data Management and Technology Center, Lawrence Berkeley National Laboratory, Berkeley, CA USA
| | | | - Nikos Kyrpides
- DOE Joint Genome Institute, Walnut Creek, CA USA
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Wayne Reeve
- Centre for Rhizobium Studies, Murdoch University, Murdoch, WA Australia
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Lajnef HB, Mejri H, Feriani A, Khemiri S, Saadaoui E, Nasri N, Tlili N. Prosopis farcta Seeds: Potential Source of Protein and Unsaturated Fatty Acids? J AM OIL CHEM SOC 2015. [DOI: 10.1007/s11746-015-2660-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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El Aafi N, Saidi N, Maltouf AF, Perez-Palacios P, Dary M, Brhada F, Pajuelo E. Prospecting metal-tolerant rhizobia for phytoremediation of mining soils from Morocco using Anthyllis vulneraria L. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2015; 22:4500-4512. [PMID: 25315928 DOI: 10.1007/s11356-014-3596-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2014] [Accepted: 09/11/2014] [Indexed: 06/04/2023]
Abstract
The aim of this work was using the legume plant Anthyllis vulneraria L. (ecotype metallicolous) as a trap plant, in order to isolate metal-tolerant rhizobial strains from metal-contaminated soils from Morocco, with pollution indexes spanning three orders of magnitude. As bioindicator, soil bacterial density was inversely correlated to the pollution index. Forty-three bulk soil bacteria and sixty two bacteria from nodules were isolated. The resistance of bacteria from nodules to heavy metals was four to ten times higher than that of bulk soil bacteria, reaching high maximum tolerable concentrations for Cd (2 mM), Cu (2 mM), Pb (7 mM), and Zn (3 mM). Besides, some strains show multiple metal-tolerant abilities and great metal biosorption onto the bacterial surface. Amplification and restriction analysis of ribosomal 16S rDNA (ARDRA) and 16S ribosomal DNA (rDNA) sequencing were used to assess biodiversity and phylogenetic position among bacteria present in nodules. Our results suggest that a great diversity of non-rhizobial bacteria (alpha- and gamma-proteobacteria) colonize nodules of Anthyllis plants in contaminated soils. Taking together, our results evidence that, in polluted soils, rhizobia can be displaced by non-rhizobial (and hence, non-fixing) strains from nodules. Thus, the selection of metal-resistant rhizobia is a key step for using A. vulneraria symbioses for in situ phytoremediation.
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Affiliation(s)
- N El Aafi
- Laboratory of Microbiology and Molecular Biology, Faculty of Sciences, University Mohamed V at Agdal, Rabat, Morocco,
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Ardley JK, Reeve WG, O'Hara GW, Yates RJ, Dilworth MJ, Howieson JG. Nodule morphology, symbiotic specificity and association with unusual rhizobia are distinguishing features of the genus Listia within the Southern African crotalarioid clade Lotononis s.l. ANNALS OF BOTANY 2013; 112:1-15. [PMID: 23712451 PMCID: PMC3690986 DOI: 10.1093/aob/mct095] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 03/25/2013] [Indexed: 05/02/2023]
Abstract
BACKGROUND AND AIMS The legume clade Lotononis sensu lato (s.l.; tribe Crotalarieae) comprises three genera: Listia, Leobordea and Lotononis sensu stricto (s.s.). Listia species are symbiotically specific and form lupinoid nodules with rhizobial species of Methylobacterium and Microvirga. This work investigated whether these symbiotic traits were confined to Listia by determining the ability of rhizobial strains isolated from species of Lotononis s.l. to nodulate Listia, Leobordea and Lotononis s.s. hosts and by examining the morphology and structure of the resulting nodules. METHODS Rhizobia were characterized by sequencing their 16S rRNA and nodA genes. Nodulation and N2 fixation on eight taxonomically diverse Lotononis s.l. species were determined in glasshouse trials. Nodules of all hosts, and the process of infection and nodule initiation in Listia angolensis and Listia bainesii, were examined by light microscopy. KEY RESULTS Rhizobia associated with Lotononis s.l. were phylogenetically diverse. Leobordea and Lotononis s.s. isolates were most closely related to Bradyrhizobium spp., Ensifer meliloti, Mesorhizobium tianshanense and Methylobacterium nodulans. Listia angolensis formed effective nodules only with species of Microvirga. Listia bainesii nodulated only with pigmented Methylobacterium. Five lineages of nodA were found. Listia angolensis and L. bainesii formed lupinoid nodules, whereas nodules of Leobordea and Lotononis s.s. species were indeterminate. All effective nodules contained uniformly infected central tissue. Listia angolensis and L. bainesii nodule initials occurred on the border of the hypocotyl and along the tap root, and nodule primordia developed in the outer cortical layer. Neither root hair curling nor infection threads were seen. CONCLUSIONS Two specificity groups occur within Lotononis s.l.: Listia species are symbiotically specific, while species of Leobordea and Lotononis s.s. are generally promiscuous and interact with rhizobia of diverse chromosomal and symbiotic lineages. The seasonally waterlogged habitat of Listia species may favour the development of symbiotic specificity.
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Affiliation(s)
- Julie K Ardley
- Centre for Rhizobium Studies, Murdoch University, Murdoch WA 6150, Australia.
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