1
|
Dávalos A, García-de los Santos A. Five copper homeostasis gene clusters encode the Cu-efflux resistome of the highly copper-tolerant Methylorubrum extorquens AM1. PeerJ 2023; 11:e14925. [PMID: 36846457 PMCID: PMC9948745 DOI: 10.7717/peerj.14925] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 01/30/2023] [Indexed: 02/22/2023] Open
Abstract
Background In the last decade, the use of copper has reemerged as a potential strategy to limit healthcare-associated infections and to control the spread of multidrug-resistant pathogens. Numerous environmental studies have proposed that most opportunistic pathogens have acquired antimicrobial resistance in their nonclinical primary habitat. Thus, it can be presumed that copper-resistant bacteria inhabiting a primary commensal niche might potentially colonize clinical environments and negatively affect the bactericidal efficacy of Cu-based treatments. The use of copper in agricultural fields is one of the most important sources of Cu pollution that may exert selection pressure for the increase of copper resistance in soil and plant-associated bacteria. To assess the emergence of copper-resistant bacteria in natural habitats, we surveyed a laboratory collection of bacterial strains belonging to the order Rhizobiales. This study proposes that Methylorubrum extorquens AM1 is an environmental isolate well adapted to thrive in copper-rich environments that could act as a reservoir of copper resistance genes. Methods The minimal inhibitory concentrations (MICs) of CuCl2 were used to estimate the copper tolerance of eight plant-associated facultative diazotrophs (PAFD) and five pink-pigmented facultative methylotrophs (PPFM) belonging to the order Rhizobiales presumed to come from nonclinical and nonmetal-polluted natural habitats based on their reported source of isolation. Their sequenced genomes were used to infer the occurrence and diversity of Cu-ATPases and the copper efflux resistome of Mr. extorquens AM1. Results These bacteria exhibited minimal inhibitory concentrations (MICs) of CuCl2 ranging between 0.020 and 1.9 mM. The presence of multiple and quite divergent Cu-ATPases per genome was a prevalent characteristic. The highest copper tolerance exhibited by Mr. extorquens AM1 (highest MIC of 1.9 mM) was similar to that found in the multimetal-resistant model bacterium Cupriavidus metallidurans CH34 and in clinical isolates of Acinetobacter baumannii. The genome-predicted copper efflux resistome of Mr. extorquens AM1 consists of five large (6.7 to 25.7 kb) Cu homeostasis gene clusters, three clusters share genes encoding Cu-ATPases, CusAB transporters, numerous CopZ chaperones, and enzymes involved in DNA transfer and persistence. The high copper tolerance and the presence of a complex Cu efflux resistome suggest the presence of relatively high copper tolerance in environmental isolates of Mr. extorquens.
Collapse
|
2
|
Jócsák I, Knolmajer B, Szarvas M, Rabnecz G, Pál-Fám F. Literature Review on the Effects of Heavy Metal Stress and Alleviating Possibilities through Exogenously Applied Agents in Alfalfa ( Medicago sativa L.). PLANTS (BASEL, SWITZERLAND) 2022; 11:2161. [PMID: 36015464 PMCID: PMC9414348 DOI: 10.3390/plants11162161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 08/17/2022] [Accepted: 08/18/2022] [Indexed: 06/15/2023]
Abstract
Heavy metals (HMs) are among the most important toxic agents since they reach the soil through various routes and accumulate in the food chain. Therefore, HMs induce problems in soil integrity and in plant, animal, and human health. Alfalfa (Medicago sativa L.) is a significant crop worldwide, utilized in animal production. Furthermore, because of its nitrogen-absorbing ability via symbiotic strains of bacteria, it increases soil productivity. However, there are relatively few studies investigating the effects of HMs and their alleviation possibilities on alfalfa plants. Therefore, the goal of this review is to clarify the current state of research into HM-induced alterations in alfalfa and to determine the extent to which externally applied microorganisms and chemical compounds can mitigate the negative effects. The aim is to indicate areas of development towards further understanding of HM detoxification in alfalfa and to identify future research directions.
Collapse
Affiliation(s)
- Ildikó Jócsák
- Institute of Agronomy, Kaposvár Campus, Hungarian University of Agriculture and Life Sciences, Guba Sándor Street 40, H-7400 Kaposvár, Hungary
| | - Bence Knolmajer
- Institute of Plant Protection, Georgikon Campus, Hungarian University of Agriculture and Life Sciences, Deák Ferenc Street 16, H-8360 Keszthely, Hungary
| | - Miklós Szarvas
- Institute of Agronomy, Kaposvár Campus, Hungarian University of Agriculture and Life Sciences, Guba Sándor Street 40, H-7400 Kaposvár, Hungary
| | - Gyula Rabnecz
- Zorvet Ltd., Wlassics Gyula Street 58, H-1181 Budapest, Hungary
| | - Ferenc Pál-Fám
- Institute of Agronomy, Kaposvár Campus, Hungarian University of Agriculture and Life Sciences, Guba Sándor Street 40, H-7400 Kaposvár, Hungary
| |
Collapse
|
3
|
Pirhanov GG. Sinorhizobium meliloti AS A PERSPECTIVE OBJECT FOR MODERN BIOTECHNOLOGY. BIOTECHNOLOGIA ACTA 2021. [DOI: 10.15407/biotech14.06.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Sinorhizobium meliloti is a Gram-negative soil nitrogen-fixing bacterium that increases the yield of legumes. There is information in the literature about the complete genome sequence of this bacterium, in addition, the polysaccharide composition of the biofilm, which is actively involved in nitrogen fixation, has been studied. The well-known nucleotide sequence, as well as the genetic and biochemical features of S. meliloti make this organism an ideal model for biotechnological research. The purpose of this work was to analyze the current data provided in the literature on the symbiotic interaction of Sinorhizobium meliloti with the host plant, and to characterize the main directions of the use of this bacterium in agriculture, bioremediation and medicine.
Collapse
|
4
|
Yang Y, Liu L, Singh RP, Meng C, Ma S, Jing C, Li Y, Zhang C. Nodule and Root Zone Microbiota of Salt-Tolerant Wild Soybean in Coastal Sand and Saline-Alkali Soil. Front Microbiol 2020; 11:2178. [PMID: 33071999 PMCID: PMC7536311 DOI: 10.3389/fmicb.2020.523142] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Accepted: 08/17/2020] [Indexed: 11/13/2022] Open
Abstract
Soil salinization limits crop growth and yield in agro-ecosystems worldwide by reducing soil health and altering the structure of microbial communities. Salt-tolerant plant growth-promoting rhizobacteria (PGPR) alleviate plant salinity stress. Wild soybean (Glycine soja Sieb. and Zucc.) is unique in agricultural ecosystems owing to its ability to grow in saline-alkali soils and fix atmospheric nitrogen via symbiotic interactions with diverse soil microbes. However, this rhizosphere microbiome and the nodule endosymbionts have not been investigated to identify PGPR. In this study, we investigated the structural and functional rhizosphere microbial communities in saline-alkali soil from the Yellow River Delta and coastal soil in China, as well as wild soybean root nodule endosymbionts. To reveal the composition of the microbial ecosystem, we performed 16S rRNA and nifH gene amplicon sequencing on root nodules and root zones under different environmental conditions. In addition, we used culture-independent methods to examine the root bacterial microbiome of wild soybean. For functional characterization of individual members of the microbiome and their impact on plant growth, we inoculated isolates from the root microbiome with wild soybean and observed nodulation. Sinorhizobium/Ensifer accounted for 97% of the root nodule microbiome, with other enriched members belonging to the phyla Actinobacteria, Bacteroidetes, Chloroflexi, Acidobacteria, and Gemmatimonadetes; the genera Sphingomonas, Microbacterium, Arthrobacter, Nocardioides, Streptomyces, Flavobacterium, Flavisolibacter, and Pseudomonas; and the family Enterobacteriaceae. Compared to saline-alkali soil from the Yellow River Delta, coastal soil was highly enriched for soybean nodules and displayed significant differences in the abundance and diversity of β-proteobacteria, δ-proteobacteria, Actinobacteria, and Bacteroidetes. Overall, the wild soybean root nodule microbiome was dominated by nutrient-providing Sinorhizobium/Ensifer and was enriched for bacterial genera that may provide salt resistance. Thus, this reductionist experimental approach provides an avenue for future systematic and functional studies of the plant root microbiome.
Collapse
Affiliation(s)
- Yingjie Yang
- Marine Agriculture Research Center, Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao, China
| | - Lei Liu
- Bureau of Agriculture and Rural Affairs of Laoshan District, Qingdao, China
| | - Raghvendra Pratap Singh
- Department of Research and Development, Biotechnology, Uttaranchal University, Dehradun, India
| | - Chen Meng
- Marine Agriculture Research Center, Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao, China
| | - Siqi Ma
- Marine Agriculture Research Center, Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao, China
| | - Changliang Jing
- Marine Agriculture Research Center, Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao, China
| | - Yiqiang Li
- Marine Agriculture Research Center, Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao, China
| | - Chengsheng Zhang
- Marine Agriculture Research Center, Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao, China
| |
Collapse
|
5
|
Dubey A, Malla MA, Kumar A, Dayanandan S, Khan ML. Plants endophytes: unveiling hidden agenda for bioprospecting toward sustainable agriculture. Crit Rev Biotechnol 2020; 40:1210-1231. [PMID: 32862700 DOI: 10.1080/07388551.2020.1808584] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Endophytic microbes are present in nearly all of the plant species known to date but how they enter and flourish inside a host plant and display multiple benefits like plant growth promotion (PGP), biodegradation, and stress alleviation are still unexplored. Until now, the majority of the research has been conducted assuming that the host-endophyte interaction is analogous to the PGP microbes, although, studies related to the mechanisms of their infection, colonization as well as conferring important traits to the plants are limited. It would be fascinating to explore the role of these endophytic microbes in host gene expression, metabolism, and the modulation of phenotypic traits, under abiotic and biotic stress conditions. In this review, we critically focused on the following areas: (i) endophytic lifestyle and the mechanism of their entry into plant tissues, (ii) how endophytes modulate the immune system of plants and affect the genotypic and phenotypic expression of host plants under abiotic and biotic stress condition, and (iii) the role of omics and other integrated genomic approaches in unraveling complex host-endophyte signaling crosstalk. Furthermore, we discussed their role in phytoremediation of heavy metal stress and whole genomic analysis based on an understanding of different metabolic pathways these endophytes utilize to combat stress.
Collapse
Affiliation(s)
- Anamika Dubey
- Department of Botany, Metagenomics and Secretomics Research Laboratory, Dr. Harisingh Gour University (A Central University), Sagar, India
| | - Muneer Ahmad Malla
- Department of Zoology, Dr. Harisingh Gour University (A Central University), Sagar, India
| | - Ashwani Kumar
- Department of Botany, Metagenomics and Secretomics Research Laboratory, Dr. Harisingh Gour University (A Central University), Sagar, India
| | - Selvadurai Dayanandan
- Department of Zoology, Dr. Harisingh Gour University (A Central University), Sagar, India.,Biology Department, Centre for Structural and Functional Genomics, Concordia University, Montreal, QC, Canada
| | - Mohammad Latif Khan
- Department of Botany, Metagenomics and Secretomics Research Laboratory, Dr. Harisingh Gour University (A Central University), Sagar, India
| |
Collapse
|
6
|
Jian L, Bai X, Zhang H, Song X, Li Z. Promotion of growth and metal accumulation of alfalfa by coinoculation with Sinorhizobium and Agrobacterium under copper and zinc stress. PeerJ 2019; 7:e6875. [PMID: 31119081 PMCID: PMC6510217 DOI: 10.7717/peerj.6875] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 03/28/2019] [Indexed: 12/31/2022] Open
Abstract
The Legume-Rhizobium symbiosis has been proposed as a promising technique for the phytoremediation of contaminated soils due to its beneficial activity in symbiotic nitrogen fixation. However, numerous studies have shown that excessive heavy metals reduce the efficiency of symbiotic nodulation with Rhizobium and inhibit plant growth. In this study, we aimed to evaluate the synergistic effects of IAA-producing bacteria and Rhizobium on Medicago lupulina growth under Cu and Zn stress. Pot experiments showed that 400 mg kg-1 Cu2 + and Zn2 + greatly inhibited plant growth, but dual inoculation of Medicago lupulina with Sinorhizobium meliloti CCNWSX0020 and Agrobacterium tumefaciens CCNWGS0286 significantly increased the number of nodules and plant biomass by enhancing antioxidant activities. Under double stress of 400 mg kg-1 Cu2 + and Zn2 +, the nodule number and nitrogenase activities of dual-inoculated plants were 48.5% and 154.4% higher, respectively, than those of plants inoculated with Sinorhizobium meliloti. The root and above-ground portion lengths of the dual-inoculated plants were 32.6% and 14.1% greater, respectively, than those of the control, while the root and above-ground portion dry weights were 34.3% and 32.2% greater, respectively, than those of the control. Compared with S. meliloti and A. tumefaciens single inoculation, coinoculation increased total Cu uptake by 39.1% and 47.5% and increased total Zn uptake by 35.4% and 44.2%, respectively, under double metal stress conditions. Therefore, coinoculation with Sinorhizobium meliloti and Agrobacterium tumefaciens enhances metal phytoextraction by increasing plant growth and antioxidant activities under Cu/Zn stress, which provides a new approach for bioremediation in heavy metal-contaminated soil.
Collapse
Affiliation(s)
- Liru Jian
- State Key Laboratory of Crop Stress Biology in Arid Areas, Northwest A&F University, Yangling, Shaanxi, China
| | - Xiaoli Bai
- Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Science, Northwest A&F University, Yangling, Shaanxi, China
| | - Hui Zhang
- Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Science, Northwest A&F University, Yangling, Shaanxi, China
| | - Xiuyong Song
- Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Science, Northwest A&F University, Yangling, Shaanxi, China
| | - Zhefei Li
- Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Science, Northwest A&F University, Yangling, Shaanxi, China
| |
Collapse
|
7
|
Chou M, Sun Y, Yang J, Wang Y, Li Y, Yuan G, Zhang D, Wang J, Wei G. Comprehensive analysis of phenotype, microstructure and global transcriptional profiling to unravel the effect of excess copper on the symbiosis between nitrogen-fixing bacteria and Medicago lupulina. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 656:1346-1357. [PMID: 30625663 DOI: 10.1016/j.scitotenv.2018.12.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 12/01/2018] [Accepted: 12/01/2018] [Indexed: 06/09/2023]
Abstract
Legume-rhizobial symbiosis plays an important role in agriculture and ecological restoration. However, knowledge of the molecular mechanisms, especially the microstructure and global transcriptional profiling, of the symbiosis process under heavy metal contamination is limited. In this study, a heavy metal-tolerant legume, Medicago lupulina, was treated with different concentrations of copper (Cu). The results showed that the early infection process was inhibited and the nodule ultrastructure was changed under 200 mg kg-1 Cu stress. Most infection threads (ITs) were prevented from entering the nodule cells, and few rhizobia were released into the host cells, in which thickening of the plant cell wall and IT wall was observed, demonstrating that rhizobial invasion was inhibited under Cu stress. RNA-seq analysis indicated that a strong shift in gene expression occurred (3257 differentially expressed genes, DEGs). The most pronounced effect was the upregulation of a set of 71 of 73 DEGs for nodule-specific cysteine-rich peptides, which have been shown to control the terminal differentiation of rhizobia in the nodules and to have antimicrobial activity. Various genes for metal transport, chelation binding and antioxidant defence were regulated. In particular, the DEGs for Cu trafficking and detoxification were induced during nodule formation. The DEGs for ethylene (ET) biosynthesis and signalling were also differentially expressed during nodulation, suggesting that the inhibition of nodulation by Cu occurred partially through ET signalling. Furthermore, the genes related to the cell wall were mostly upregulated and most likely involved in cell wall thickening. These findings provide an integrated understanding of the effects of Cu on legume nodule symbiosis at the molecular and phenotypic levels.
Collapse
Affiliation(s)
- Minxia Chou
- State Key Laboratory of Crop Stress Biology in Arid Areas and College of Life Sciences, Northwest A&F University, Yangling 712100, China
| | - Yali Sun
- State Key Laboratory of Crop Stress Biology in Arid Areas and College of Life Sciences, Northwest A&F University, Yangling 712100, China
| | - Jieyu Yang
- State Key Laboratory of Crop Stress Biology in Arid Areas and College of Life Sciences, Northwest A&F University, Yangling 712100, China
| | - Yujie Wang
- State Key Laboratory of Crop Stress Biology in Arid Areas and College of Life Sciences, Northwest A&F University, Yangling 712100, China
| | - Yajuan Li
- State Key Laboratory of Crop Stress Biology in Arid Areas and College of Life Sciences, Northwest A&F University, Yangling 712100, China
| | - Guijie Yuan
- State Key Laboratory of Crop Stress Biology in Arid Areas and College of Life Sciences, Northwest A&F University, Yangling 712100, China
| | - Dehui Zhang
- State Key Laboratory of Crop Stress Biology in Arid Areas and College of Life Sciences, Northwest A&F University, Yangling 712100, China
| | - Jiamei Wang
- State Key Laboratory of Crop Stress Biology in Arid Areas and College of Life Sciences, Northwest A&F University, Yangling 712100, China
| | - Gehong Wei
- State Key Laboratory of Crop Stress Biology in Arid Areas and College of Life Sciences, Northwest A&F University, Yangling 712100, China.
| |
Collapse
|
8
|
Fagorzi C, Checcucci A, diCenzo GC, Debiec-Andrzejewska K, Dziewit L, Pini F, Mengoni A. Harnessing Rhizobia to Improve Heavy-Metal Phytoremediation by Legumes. Genes (Basel) 2018; 9:genes9110542. [PMID: 30413093 PMCID: PMC6266702 DOI: 10.3390/genes9110542] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 11/05/2018] [Accepted: 11/06/2018] [Indexed: 12/15/2022] Open
Abstract
Rhizobia are bacteria that can form symbiotic associations with plants of the Fabaceae family, during which they reduce atmospheric di-nitrogen to ammonia. The symbiosis between rhizobia and leguminous plants is a fundamental contributor to nitrogen cycling in natural and agricultural ecosystems. Rhizobial microsymbionts are a major reason why legumes can colonize marginal lands and nitrogen-deficient soils. Several leguminous species have been found in metal-contaminated areas, and they often harbor metal-tolerant rhizobia. In recent years, there have been numerous efforts and discoveries related to the genetic determinants of metal resistance by rhizobia, and on the effectiveness of such rhizobia to increase the metal tolerance of host plants. Here, we review the main findings on the metal resistance of rhizobia: the physiological role, evolution, and genetic determinants, and the potential to use native and genetically-manipulated rhizobia as inoculants for legumes in phytoremediation practices.
Collapse
Affiliation(s)
- Camilla Fagorzi
- Department of Biology, University of Florence, Via Madonna del Piano 6, 50019 Sesto Fiorentino, Italy.
| | - Alice Checcucci
- Department of Biology, University of Florence, Via Madonna del Piano 6, 50019 Sesto Fiorentino, Italy.
| | - George C diCenzo
- Department of Biology, University of Florence, Via Madonna del Piano 6, 50019 Sesto Fiorentino, Italy.
| | - Klaudia Debiec-Andrzejewska
- Laboratory of Environmental Pollution Analysis, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland.
| | - Lukasz Dziewit
- Department of Bacterial Genetics, Institute of Microbiology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland.
| | - Francesco Pini
- Department of Agri-food Production and Environmental Science, University of Florence, 50144 Florence, Italy.
| | - Alessio Mengoni
- Department of Biology, University of Florence, Via Madonna del Piano 6, 50019 Sesto Fiorentino, Italy.
| |
Collapse
|
9
|
Transcriptome Response to Heavy Metals in Sinorhizobium meliloti CCNWSX0020 Reveals New Metal Resistance Determinants That Also Promote Bioremediation by Medicago lupulina in Metal-Contaminated Soil. Appl Environ Microbiol 2017; 83:AEM.01244-17. [PMID: 28778889 DOI: 10.1128/aem.01244-17] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2017] [Accepted: 07/26/2017] [Indexed: 01/16/2023] Open
Abstract
The symbiosis of the highly metal-resistant Sinorhizobium meliloti CCNWSX0020 and Medicago lupulina has been considered an efficient tool for bioremediation of heavy metal-polluted soils. However, the metal resistance mechanisms of S. meliloti CCNWSX00200 have not been elucidated in detail. Here we employed a comparative transcriptome approach to analyze the defense mechanisms of S. meliloti CCNWSX00200 against Cu or Zn exposure. Six highly upregulated transcripts involved in Cu and Zn resistance were identified through deletion mutagenesis, including genes encoding a multicopper oxidase (CueO), an outer membrane protein (Omp), sulfite oxidoreductases (YedYZ), and three hypothetical proteins (a CusA-like protein, a FixH-like protein, and an unknown protein), and the corresponding mutant strains showed various degrees of sensitivity to multiple metals. The Cu-sensitive mutant (ΔcueO) and three mutants that were both Cu and Zn sensitive (ΔyedYZ, ΔcusA-like, and ΔfixH-like) were selected for further study of the effects of these metal resistance determinants on bioremediation. The results showed that inoculation with the ΔcueO mutant severely inhibited infection establishment and nodulation of M. lupulina under Cu stress, while inoculation with the ΔyedYZ and ΔfixH-like mutants decreased just the early infection frequency and nodulation under Cu and Zn stresses. In contrast, inoculation with the ΔcusA-like mutant almost led to loss of the symbiotic capacity of M. lupulina to even grow in uncontaminated soil. Moreover, the antioxidant enzyme activity and metal accumulation in roots of M. lupulina inoculated with all mutants were lower than those with the wild-type strain. These results suggest that heavy metal resistance determinants may promote bioremediation by directly or indirectly influencing formation of the rhizobium-legume symbiosis.IMPORTANCE Rhizobium-legume symbiosis has been promoted as an appropriate tool for bioremediation of heavy metal-contaminated soils. Considering the plant-growth-promoting traits and survival advantage of metal-resistant rhizobia in contaminated environments, more heavy metal-resistant rhizobia and genetically manipulated strains were investigated. In view of the genetic diversity of metal resistance determinants in rhizobia, their effects on phytoremediation by the rhizobium-legume symbiosis must be different and depend on their specific assigned functions. Our work provides a better understanding of the mechanism of heavy metal resistance determinants involved in the rhizobium-legume symbiosis, and in further studies, genetically modified rhizobia harboring effective heavy metal resistance determinants may be engineered for the practical application of rhizobium-legume symbiosis for bioremediation in metal-contaminated soils.
Collapse
|
10
|
Pérez-Palacios P, Romero-Aguilar A, Delgadillo J, Doukkali B, Caviedes MA, Rodríguez-Llorente ID, Pajuelo E. Double genetically modified symbiotic system for improved Cu phytostabilization in legume roots. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2017; 24:14910-14923. [PMID: 28480491 DOI: 10.1007/s11356-017-9092-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 04/24/2017] [Indexed: 06/07/2023]
Abstract
Excess copper (Cu) in soils has deleterious effects on plant growth and can pose a risk to human health. In the last decade, legume-rhizobium symbioses became attractive biotechnological tools for metal phytostabilization. For this technique being useful, metal-tolerant symbionts are required, which can be generated through genetic manipulation.In this work, a double symbiotic system was engineered for Cu phytostabilization: On the one hand, composite Medicago truncatula plants expressing the metallothionein gene mt4a from Arabidopsis thaliana in roots were obtained to improve plant Cu tolerance. On the other hand, a genetically modified Ensifer medicae strain, expressing copper resistance genes copAB from Pseudomonas fluorescens driven by a nodulation promoter, nifHp, was used for plant inoculation. Our results indicated that expression of mt4a in composite plants ameliorated plant growth and nodulation and enhanced Cu tolerance. Lower levels of ROS-scavenging enzymes and of thiobarbituric acid reactive substances (TBARS), such as malondialdehyde (a marker of lipid peroxidation), suggested reduced oxidative stress. Furthermore, inoculation with the genetically modified Ensifer further improved root Cu accumulation without altering metal loading to shoots, leading to diminished values of metal translocation from roots to shoots. The double modified partnership is proposed as a suitable tool for Cu rhizo-phytostabilization.
Collapse
Affiliation(s)
- Patricia Pérez-Palacios
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad de Sevilla, c/ Profesor García González, 2, 41012, Sevilla, Spain
| | - Asunción Romero-Aguilar
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad de Sevilla, c/ Profesor García González, 2, 41012, Sevilla, Spain
| | - Julián Delgadillo
- Área de Microbiología, Colegio de Post-Graduados, Campus de Montecillo, Carretera Federal México-Texcoco, 56230, Montecillo, Mexico
| | - Bouchra Doukkali
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad de Sevilla, c/ Profesor García González, 2, 41012, Sevilla, Spain
| | - Miguel A Caviedes
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad de Sevilla, c/ Profesor García González, 2, 41012, Sevilla, Spain
| | - Ignacio D Rodríguez-Llorente
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad de Sevilla, c/ Profesor García González, 2, 41012, Sevilla, Spain
| | - Eloísa Pajuelo
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad de Sevilla, c/ Profesor García González, 2, 41012, Sevilla, Spain.
| |
Collapse
|
11
|
Liang J, Zhang M, Lu M, Li Z, Shen X, Chou M, Wei G. Functional characterization of a csoR-cueA divergon in Bradyrhizobium liaoningense CCNWSX0360, involved in copper, zinc and cadmium cotolerance. Sci Rep 2016; 6:35155. [PMID: 27725778 PMCID: PMC5057107 DOI: 10.1038/srep35155] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 09/26/2016] [Indexed: 12/14/2022] Open
Abstract
Random mutagenesis in a symbiotic nitrogen-fixing Bradyrhizobium liaoningense CCNWSX0360 (Bln0360) using Tn5 identified five copper (Cu) resistance-related genes. They were functionally sorted into three groups: transmembrane transport (cueA and tolC); oxidation (copA); and protection of the membrane barrier (lptE and ctpA). The gene cueA, together with the upstream csoR (Cu-sensitive operon repressor), constituted a csoR-cueA divergon which plays a crucial role in Cu homeostasis. Deletion of cueA decreased the Cu tolerance of cells, and complementation of this mutant restored comparable Cu resistance to that of the wild-type. Transcriptional and fusion expression analysis demonstrated that csoR-cueA divergon was up-regulated by both the monovalent Cu+ and divalent Zn2+/Cd2+, and negatively regulated by transcriptional repressor CsoR, via a bidirectional promoter. Deletion of csoR renders the cell hyper-resistant to Cu, Zn and Cd. Although predicted to encode a Cu transporting P-type ATPase (CueA), cueA also conferred resistance to zinc and cadmium; two putative N-MBDs (N-terminal metal binding domains) of CueA were required for the Cu/Zn/Cd tolerance. Moreover, cueA is needed for nodulation competitiveness of B. liaoningense in Cu rich conditions. Together, the results demonstrated a crucial role for the csoR-cueA divergon as a component of the multiple-metal resistance machinery in B. liaoningense.
Collapse
Affiliation(s)
- Jianqiang Liang
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
| | - Mingzhe Zhang
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
| | - Mingmei Lu
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
| | - Zhefei Li
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
| | - Xihui Shen
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
| | - Minxia Chou
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
| | - Gehong Wei
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
| |
Collapse
|
12
|
Lu M, Li Z, Liang J, Wei Y, Rensing C, Wei G. Zinc Resistance Mechanisms of P1B-type ATPases in Sinorhizobium meliloti CCNWSX0020. Sci Rep 2016; 6:29355. [PMID: 27378600 PMCID: PMC4932525 DOI: 10.1038/srep29355] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 06/10/2016] [Indexed: 12/12/2022] Open
Abstract
The Sinorhizobium meliloti (S. meliloti) strain CCNWSX0020 displayed tolerance to high levels exposures of multiple metals and growth promotion of legume plants grown in metal-contaminated soil. However, the mechanism of metal-resistant strain remains unknown. We used five P1B-ATPases deletions by designating as ∆copA1b, ∆fixI1, ∆copA3, ∆zntA and ∆nia, respectively to investigate the role of P1B-ATPases in heavy metal resistance of S. meliloti. The ∆copA1b and ∆zntA mutants were sensitive to zinc (Zn), cadmium (Cd) and lead (Pb) in different degree, whereas the other mutants had no significant influence on the metal resistance. Moreover, the expression of zntA was induced by Zn, Cd and Pb whereas copA1b was induced by copper (Cu) and silver (Ag). This two deletions could led to the increased intracellular concentrations of Zn, Pb and Cd, but not of Cu. Complementation of ∆copA1b and ∆zntA mutants showed a restoration of tolerance to Zn, Cd and Pb to a certain extent. Taken together, the results suggest an important role of copA1b and zntA in Zn homeostasis and Cd and Pb detoxification in S. meliloti CCNWSX0020.
Collapse
Affiliation(s)
- Mingmei Lu
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A and F University, Yangling, Shaanxi, China
| | - Zhefei Li
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A and F University, Yangling, Shaanxi, China
| | - Jianqiang Liang
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A and F University, Yangling, Shaanxi, China
| | - Yibing Wei
- College of Life Sciences, Nankai University, Tianjin, China
| | | | - Gehong Wei
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A and F University, Yangling, Shaanxi, China
| |
Collapse
|
13
|
Nocelli N, Bogino PC, Banchio E, Giordano W. Roles of Extracellular Polysaccharides and Biofilm Formation in Heavy Metal Resistance of Rhizobia. MATERIALS 2016; 9:ma9060418. [PMID: 28773540 PMCID: PMC5456807 DOI: 10.3390/ma9060418] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Revised: 05/09/2016] [Accepted: 05/17/2016] [Indexed: 12/04/2022]
Abstract
Bacterial surface components and extracellular compounds, particularly flagella, lipopolysaccharides (LPSs), and exopolysaccharides (EPSs), in combination with environmental signals and quorum-sensing signals, play crucial roles in bacterial autoaggregation, biofilm development, survival, and host colonization. The nitrogen-fixing species Sinorhizobium meliloti (S. meliloti) produces two symbiosis-promoting EPSs: succinoglycan (or EPS I) and galactoglucan (or EPS II). Studies of the S.meliloti/alfalfa symbiosis model system have revealed numerous biological functions of EPSs, including host specificity, participation in early stages of host plant infection, signaling molecule during plant development, and (most importantly) protection from environmental stresses. We evaluated functions of EPSs in bacterial resistance to heavy metals and metalloids, which are known to affect various biological processes. Heavy metal resistance, biofilm production, and co-culture were tested in the context of previous studies by our group. A range of mercury (Hg II) and arsenic (As III) concentrations were applied to S. meliloti wild type strain and to mutant strains defective in EPS I and EPS II. The EPS production mutants were generally most sensitive to the metals. Our findings suggest that EPSs are necessary for the protection of bacteria from either Hg (II) or As (III) stress. Previous studies have described a pump in S. meliloti that causes efflux of arsenic from cells to surrounding culture medium, thereby protecting them from this type of chemical stress. The presence of heavy metals or metalloids in culture medium had no apparent effect on formation of biofilm, in contrast to previous reports that biofilm formation helps protect various microorganism species from adverse environmental conditions. In co-culture experiments, EPS-producing heavy metal resistant strains exerted a protective effect on AEPS-non-producing, heavy metal-sensitive strains; a phenomenon termed “rescuing” of the non-resistant strain.
Collapse
Affiliation(s)
- Natalia Nocelli
- Departamento de Biología Molecular, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba X5804BYA, Argentina.
| | - Pablo C Bogino
- Departamento de Biología Molecular, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba X5804BYA, Argentina.
| | - Erika Banchio
- Departamento de Biología Molecular, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba X5804BYA, Argentina.
| | - Walter Giordano
- Departamento de Biología Molecular, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba X5804BYA, Argentina.
| |
Collapse
|
14
|
Hao X, Xie P, Zhu YG, Taghavi S, Wei G, Rensing C. Copper tolerance mechanisms of Mesorhizobium amorphae and its role in aiding phytostabilization by Robinia pseudoacacia in copper contaminated soil. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:2328-2340. [PMID: 25594414 DOI: 10.1021/es504956a] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The legume-rhizobium symbiosis has been proposed as an important system for phytoremediation of heavy metal contaminated soils due to its beneficial activity of symbiotic nitrogen fixation. However, little is known about metal resistant mechanism of rhizobia and the role of metal resistance determinants in phytoremediation. In this study, copper resistance mechanisms were investigated for a multiple metal resistant plant growth promoting rhizobium, Mesorhizobium amorphae 186. Three categories of determinants involved in copper resistance were identified through transposon mutagenesis, including genes encoding a P-type ATPase (CopA), hypothetical proteins, and other proteins (a GTP-binding protein and a ribosomal protein). Among these determinants, copA played the dominant role in copper homeostasis of M. amorphae 186. Mutagenesis of a hypothetical gene lipA in mutant MlipA exhibited pleiotropic phenotypes including sensitivity to copper, blocked symbiotic capacity and inhibited growth. In addition, the expression of cusB encoding part of an RND-type efflux system was induced by copper. To explore the possible role of copper resistance mechanism in phytoremediation of copper contaminated soil, the symbiotic nodulation and nitrogen fixation abilities were compared using a wild-type strain, a copA-defective mutant, and a lipA-defective mutant. Results showed that a copA deletion did not affect the symbiotic capacity of rhizobia under uncontaminated condition, but the protective role of copA in symbiotic processes at high copper concentration is likely concentration-dependent. In contrast, inoculation of a lipA-defective strain led to significant decreases in the functional nodule numbers, total N content, plant biomass and leghemoglobin expression level of Robinia pseudoacacia even under conditions of uncontaminated soil. Moreover, plants inoculated with lipA-defective strain accumulated much less copper than both the wild-type strain and the copA-defective strain, suggesting an important role of a healthy symbiotic relationship between legume and rhizobia in phytostabilization.
Collapse
Affiliation(s)
- Xiuli Hao
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, College of Life Sciences, Northwest A&F University , Yangling, Shaanxi 712100, China
| | | | | | | | | | | |
Collapse
|
15
|
Xie P, Hao X, Herzberg M, Luo Y, Nies DH, Wei G. Genomic analyses of metal resistance genes in three plant growth promoting bacteria of legume plants in Northwest mine tailings, China. J Environ Sci (China) 2015; 27:179-187. [PMID: 25597676 DOI: 10.1016/j.jes.2014.07.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Revised: 06/11/2014] [Accepted: 07/31/2014] [Indexed: 06/04/2023]
Abstract
To better understand the diversity of metal resistance genetic determinant from microbes that survived at metal tailings in northwest of China, a highly elevated level of heavy metal containing region, genomic analyses was conducted using genome sequence of three native metal-resistant plant growth promoting bacteria (PGPB). It shows that: Mesorhizobium amorphae CCNWGS0123 contains metal transporters from P-type ATPase, CDF (Cation Diffusion Facilitator), HupE/UreJ and CHR (chromate ion transporter) family involved in copper, zinc, nickel as well as chromate resistance and homeostasis. Meanwhile, the putative CopA/CueO system is expected to mediate copper resistance in Sinorhizobium meliloti CCNWSX0020 while ZntA transporter, assisted with putative CzcD, determines zinc tolerance in Agrobacterium tumefaciens CCNWGS0286. The greenhouse experiment provides the consistent evidence of the plant growth promoting effects of these microbes on their hosts by nitrogen fixation and/or indoleacetic acid (IAA) secretion, indicating a potential in-site phytoremediation usage in the mining tailing regions of China.
Collapse
Affiliation(s)
- Pin Xie
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, College of Life Science, Northwest A&F University, Yangling, Shaanxi 712100, China; Molecular Microbiology, Institute for Biochemistry and Biotechnology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), 06120, Germany.
| | - Xiuli Hao
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, College of Life Science, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Martin Herzberg
- Molecular Microbiology, Institute for Biochemistry and Biotechnology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), 06120, Germany
| | - Yantao Luo
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, College of Life Science, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Dietrich H Nies
- Molecular Microbiology, Institute for Biochemistry and Biotechnology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), 06120, Germany
| | - Gehong Wei
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, College of Life Science, Northwest A&F University, Yangling, Shaanxi 712100, China.
| |
Collapse
|