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Kerdsomboon K, Techo T, Mhuantong W, Limcharoensuk T, Luangkamchorn ST, Laoburin P, Auesukaree C. Genomic and transcriptomic analyses reveal insights into cadmium resistance mechanisms of Cupriavidus nantongensis strain E324. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 952:175915. [PMID: 39216765 DOI: 10.1016/j.scitotenv.2024.175915] [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: 06/22/2024] [Revised: 08/14/2024] [Accepted: 08/29/2024] [Indexed: 09/04/2024]
Abstract
The cadmium-resistant Cupriavidus sp. strain E324 has been previously shown to have a high potential for use in cadmium (Cd) remediation, due to its high capacity for cadmium bioaccumulation. According to the comparative genomic analysis, the strain E324 was most closely related to C. nantongensis X1T, indicating that the strain E324 should be re-identified as C. nantongensis. To unravel the Cd tolerance mechanisms of C. nantongensis strain E324, the transcriptional response of this strain to acute Cd exposure was assessed using RNA-seq-based transcriptome analysis, followed by validation through qRT-PCR. The results showed that the upregulated Differentially Expressed Genes (DEGs) were significantly enriched in categories related to metal binding and transport, phosphate transport, and oxidative stress response. Consistently, we observed significant increases in both the cell wall and intracellular contents of certain essential metals (Cu, Fe, Mn, and Zn) upon Cd exposure. Among these, only the Zn pretreatment resulting in high Zn accumulation in the cell walls could enhance bacterial growth under Cd stress conditions through its role in inhibiting Cd accumulation. Additionally, the promotion of catalase activity and glutathione metabolism upon Cd exposure to cope with Cd-induced oxidative stress was demonstrated. Meanwhile, the upregulation of phosphate transport-related genes upon Cd treatment seems to be the bacterial response to Cd-induced phosphate depletion. Altogether, our findings suggest that these adaptive responses are critical mechanisms contributing to increased Cd tolerance in C. nantongensis strain E324 via the enhancement of metal-chelating and antioxidant capacities of the cells.
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Affiliation(s)
- Kittikhun Kerdsomboon
- Chulabhorn International College of Medicine, Thammasat University, Pathum Thani 12120, Thailand; Mahidol University-Osaka University Collaborative Research Center for Bioscience and Biotechnology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | - Todsapol Techo
- Department of Biology, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand
| | - Wuttichai Mhuantong
- National Center for Genetic Engineering and Biotechnology (BIOTEC), Thailand Science Park, Pathum Thani 12120, Thailand
| | - Tossapol Limcharoensuk
- Mahidol University-Osaka University Collaborative Research Center for Bioscience and Biotechnology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | - Supinda Tatip Luangkamchorn
- Mahidol University-Osaka University Collaborative Research Center for Bioscience and Biotechnology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand; Analytical Sciences and National Doping Test Institute, Mahidol University, Bangkok 10400, Thailand
| | - Patcharee Laoburin
- Mahidol University-Osaka University Collaborative Research Center for Bioscience and Biotechnology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand; Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | - Choowong Auesukaree
- Mahidol University-Osaka University Collaborative Research Center for Bioscience and Biotechnology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand; Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
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Zhang X, Zhang L, Yu T, Gao Y, Zhai T, Zhao T, Xing Z. Genetic response analysis of Beauveria bassiana Z1 under high concentration Cd(II) stress. JOURNAL OF HAZARDOUS MATERIALS 2024; 464:132984. [PMID: 37995637 DOI: 10.1016/j.jhazmat.2023.132984] [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: 06/04/2023] [Revised: 10/27/2023] [Accepted: 11/08/2023] [Indexed: 11/25/2023]
Abstract
Cadmium (Cd(II)) has carcinogenic and teratogenic toxicity, which can be accumulated in the human body through the food chain, endangering human health and life. In this study, a highly Cd(II)-tolerant fungus named Beauveria bassiana Z1 was studied, and its Cd(Ⅱ) removal efficiency was 71.2% when the Cd(II) concentration was 10 mM. Through bioanalysis and experimental verification of the transcriptome data, it was found that cadmium entered the cells through calcium ion channels, and then complexed with intracellular glutathione (GSH) and stored in vacuoles or excluded extracellular by ABC transporters. Cytochrome P450 was significantly upregulated in many pathways and actively participated in detoxification related reactions. The addition of cytochrome inhibitor taxifolin reduced the removal efficiency of Cd(II) by 45%. In the analysis, it demonstrated that ACOX1 gene and OPR gene of jasmonic acid (JA) synthesis pathway were significantly up-regulated, and were correlated with bZIP family transcription factors cpc-1_0 and pa p1_0. The results showed that exogenous JA could improve the removal efficiency of Cd(II) by strain Z1.
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Affiliation(s)
- Xiaoping Zhang
- School of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400054, China
| | - Lijie Zhang
- School of Pharmacy and Bioengineering, Chongqing University of Technology, Chongqing 400054, China.
| | - Tiantian Yu
- School of Pharmacy and Bioengineering, Chongqing University of Technology, Chongqing 400054, China
| | - Yanhui Gao
- School of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400054, China
| | - Tianrui Zhai
- School of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400054, China
| | - Tiantao Zhao
- School of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400054, China
| | - Zhilin Xing
- School of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400054, China
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Verbeelen T, Fernandez CA, Nguyen TH, Gupta S, Aarts R, Tabury K, Leroy B, Wattiez R, Vlaeminck SE, Leys N, Ganigué R, Mastroleo F. Whole transcriptome analysis highlights nutrient limitation of nitrogen cycle bacteria in simulated microgravity. NPJ Microgravity 2024; 10:3. [PMID: 38200027 PMCID: PMC10781756 DOI: 10.1038/s41526-024-00345-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 01/01/2024] [Indexed: 01/12/2024] Open
Abstract
Regenerative life support systems (RLSS) will play a vital role in achieving self-sufficiency during long-distance space travel. Urine conversion into a liquid nitrate-based fertilizer is a key process in most RLSS. This study describes the effects of simulated microgravity (SMG) on Comamonas testosteroni, Nitrosomonas europaea, Nitrobacter winogradskyi and a tripartite culture of the three, in the context of nitrogen recovery for the Micro-Ecological Life Support System Alternative (MELiSSA). Rotary cell culture systems (RCCS) and random positioning machines (RPM) were used as SMG analogues. The transcriptional responses of the cultures were elucidated. For CO2-producing C. testosteroni and the tripartite culture, a PermaLifeTM PL-70 cell culture bag mounted on an in-house 3D-printed holder was applied to eliminate air bubble formation during SMG cultivation. Gene expression changes indicated that the fluid dynamics in SMG caused nutrient and O2 limitation. Genes involved in urea hydrolysis and nitrification were minimally affected, while denitrification-related gene expression was increased. The findings highlight potential challenges for nitrogen recovery in space.
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Affiliation(s)
- Tom Verbeelen
- Nuclear Medical Applications, Belgian Nuclear Research Centre (SCK CEN), Boeretang 200, 2400, Mol, Belgium
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, 9000, Ghent, Belgium
| | - Celia Alvarez Fernandez
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, 9000, Ghent, Belgium
| | - Thanh Huy Nguyen
- Department of Proteomics and Microbiology, University of Mons, Av. Du Champs de Mars 6, 7000, Mons, Belgium
| | - Surya Gupta
- Nuclear Medical Applications, Belgian Nuclear Research Centre (SCK CEN), Boeretang 200, 2400, Mol, Belgium
| | - Raf Aarts
- Nuclear Medical Applications, Belgian Nuclear Research Centre (SCK CEN), Boeretang 200, 2400, Mol, Belgium
| | - Kevin Tabury
- Nuclear Medical Applications, Belgian Nuclear Research Centre (SCK CEN), Boeretang 200, 2400, Mol, Belgium
| | - Baptiste Leroy
- Department of Proteomics and Microbiology, University of Mons, Av. Du Champs de Mars 6, 7000, Mons, Belgium
| | - Ruddy Wattiez
- Department of Proteomics and Microbiology, University of Mons, Av. Du Champs de Mars 6, 7000, Mons, Belgium
| | - Siegfried E Vlaeminck
- Research Group of Sustainable Energy, Air and Water Technology, Department of Bioscience Engineering, University of Antwerp, Groenenborgerlaan 171, 2020, Antwerp, Belgium
- Centre for Advanced Process Technology for Urban REsource Recovery (CAPTURE), Frieda Saeysstraat 1, 9052, Ghent, Belgium
| | - Natalie Leys
- Nuclear Medical Applications, Belgian Nuclear Research Centre (SCK CEN), Boeretang 200, 2400, Mol, Belgium
| | - Ramon Ganigué
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, 9000, Ghent, Belgium
- Centre for Advanced Process Technology for Urban REsource Recovery (CAPTURE), Frieda Saeysstraat 1, 9052, Ghent, Belgium
| | - Felice Mastroleo
- Nuclear Medical Applications, Belgian Nuclear Research Centre (SCK CEN), Boeretang 200, 2400, Mol, Belgium.
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Huang M, Shen S, Meng Z, Si G, Wu X, Feng T, Liu C, Chen J, Duan C. Mechanisms involved in the sequestration and resistance of cadmium for a plant-associated Pseudomonas strain. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2023; 266:115527. [PMID: 37806135 DOI: 10.1016/j.ecoenv.2023.115527] [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: 03/14/2023] [Revised: 09/07/2023] [Accepted: 09/24/2023] [Indexed: 10/10/2023]
Abstract
Understanding Cd-resistant bacterial cadmium (Cd) resistance systems is crucial for improving microremediation in Cd-contaminated environments. However, these mechanisms are not fully understood in plant-associated bacteria. In the present study, we investigated the mechanisms underlying Cd sequestration and resistance in the strain AN-B15. These results showed that extracellular Cd sequestration by complexation in strain AN-B15 was primarily responsible for the removal of Cd from the solution. Transcriptome analyses have shown that the mechanisms of Cd resistance at the transcriptional level involve collaborative processes involving multiple metabolic pathways. The AN-B15 strain upregulated the expression of genes related to exopolymeric substance synthesis, metal transport, Fe-S cluster biogenesis, iron recruitment, reactive oxygen species oxidative stress defense, and DNA and protein repair to resist Cd-induced stress. Furthermore, inoculation with AN-B15 alleviated Cd-induced toxicity and reduced Cd uptake in the shoots of wheat seedlings, indicating its potential for remediation. Overall, the results improve our understanding of the mechanisms involved in Cd resistance in bacteria and thus have important implications for improving microremediation.
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Affiliation(s)
- Mingyu Huang
- Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, School of Ecology and Environmental Science, Yunnan University, Kunming 650091, China
| | - Shili Shen
- Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, School of Ecology and Environmental Science, Yunnan University, Kunming 650091, China
| | - Zhuang Meng
- School of Agriculture, Yunnan University, Kunming 650091, China
| | - Guangzheng Si
- Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, School of Ecology and Environmental Science, Yunnan University, Kunming 650091, China
| | - Xinni Wu
- Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, School of Ecology and Environmental Science, Yunnan University, Kunming 650091, China
| | - Tingting Feng
- Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, School of Ecology and Environmental Science, Yunnan University, Kunming 650091, China
| | - Chang'e Liu
- Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, School of Ecology and Environmental Science, Yunnan University, Kunming 650091, China
| | - Jinquan Chen
- Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, School of Ecology and Environmental Science, Yunnan University, Kunming 650091, China.
| | - Changqun Duan
- Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, School of Ecology and Environmental Science, Yunnan University, Kunming 650091, China; School of Agriculture, Yunnan University, Kunming 650091, China.
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Huang Q, Liu Z, Guo Y, Li B, Yang Z, Liu X, Ni J, Li X, Zhang X, Zhou N, Yin H, Jiang C, Hao L. Coal-source acid mine drainage reduced the soil multidrug-dominated antibiotic resistome but increased the heavy metal(loid) resistome and energy production-related metabolism. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 873:162330. [PMID: 36813198 DOI: 10.1016/j.scitotenv.2023.162330] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 02/07/2023] [Accepted: 02/15/2023] [Indexed: 06/18/2023]
Abstract
A recent global scale study found that mining-impacted environments have multi-antibiotic resistance gene (ARG)-dominated resistomes with an abundance similar to urban sewage but much higher than freshwater sediment. These findings raised concern that mining may increase the risk of ARG environmental proliferation. The current study assessed how typical multimetal(loid)-enriched coal-source acid mine drainage (AMD) contamination affects soil resistomes by comparing with background soils unaffected by AMD. Both contaminated and background soils have multidrug-dominated antibiotic resistomes attributed to the acidic environment. AMD-contaminated soils had a lower relative abundance of ARGs (47.45 ± 23.34 ×/Gb) than background soils (85.47 ± 19.71 ×/Gb) but held high-level heavy metal(loid) resistance genes (MRGs, 133.29 ± 29.36 ×/Gb) and transposase- and insertion sequence-dominated mobile genetic elements (MGEs, 188.51 ± 21.81 ×/Gb), which was 56.26 % and 412.12 % higher than background soils, respectively. Procrustes analysis showed that the microbial community and MGEs exerted more influence on driving heavy metal(loid) resistome variation than antibiotic resistome. The microbial community increased energy production-related metabolism to fulfill the increasing energy needs required by acid and heavy metal(loid) resistance. Horizontal gene transfer (HGT) events primarily exchanged energy- and information-related genes to adapt to the harsh AMD environment. These findings provide new insight into the risk of ARG proliferation in mining environments.
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Affiliation(s)
- Qiang Huang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, PR China
| | - Zhenghua Liu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, PR China; School of Minerals Processing and Bioengineering, Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha 410083, PR China
| | - Yuan Guo
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, PR China
| | - Bao Li
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Zhenni Yang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, PR China
| | - Xiaoling Liu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, PR China
| | - Jianmei Ni
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, PR China
| | - Xiutong Li
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Xi Zhang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Nan Zhou
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, PR China
| | - Huaqun Yin
- School of Minerals Processing and Bioengineering, Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha 410083, PR China
| | - Chengying Jiang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Likai Hao
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an 710061, PR China.
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He Z, Shen J, Li Q, Yang Y, Zhang D, Pan X. Bacterial metal(loid) resistance genes (MRGs) and their variation and application in environment: A review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 871:162148. [PMID: 36758696 DOI: 10.1016/j.scitotenv.2023.162148] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 02/01/2023] [Accepted: 02/06/2023] [Indexed: 06/18/2023]
Abstract
Toxic metal(loid)s are widespread and permanent in the biosphere, and bacteria have evolved a wide variety of metal(loid) resistance genes (MRGs) to resist the stress of excess metal(loid)s. Via active efflux, permeability barriers, extracellular/intracellular sequestration, enzymatic detoxification and reduction in metal(loid)s sensitivity of cellular targets, the key components of bacterial cells are protected from toxic metal(loid)s to maintain their normal physiological functions. Exploiting bacterial metal(loid) resistance mechanisms, MRGs have been applied in many environmental fields. Based on the specific binding ability of MRGs-encoded regulators to metal(loid)s, MRGs-dependent biosensors for monitoring environmental metal(loid)s are developed. MRGs-related biotechnologies have been applied to environmental remediation of metal(loid)s by using the metal(loid) tolerance, biotransformation, and biopassivation abilities of MRGs-carrying microorganisms. In this work, we review the historical evolution, resistance mechanisms, environmental variation, and environmental applications of bacterial MRGs. The potential hazards, unresolved problems, and future research directions are also discussed.
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Affiliation(s)
- Zhanfei He
- Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou, China
| | - Jiaquan Shen
- Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou, China
| | - Qunqun Li
- Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou, China
| | - Yingli Yang
- Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou, China
| | - Daoyong Zhang
- Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou, China
| | - Xiangliang Pan
- Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou, China.
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Lekired A, Cherif-Silini H, Silini A, Ben Yahia H, Ouzari HI. Comparative genomics reveals the acquisition of mobile genetic elements by the plant growth-promoting Pantoea eucrina OB49 in polluted environments. Genomics 2023; 115:110579. [PMID: 36792019 DOI: 10.1016/j.ygeno.2023.110579] [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: 06/17/2022] [Revised: 02/08/2023] [Accepted: 02/09/2023] [Indexed: 02/15/2023]
Abstract
Heavy metal-tolerant plant growth-promoting bacteria (PGPB) have gained popularity in bioremediation in recent years. A genome-assisted study of a heavy metal-tolerant PGPB Pantoea eucrina OB49 isolated from the rhizosphere of wheat grown on a heavy metal-contaminated site is presented. Comparative pan-genome analysis indicated that OB49 acquired heavy metal resistance genes through horizontal gene transfer. On contigs S10 and S12, OB49 has two arsRBCH operons that give arsenic resistance. On the S12 contig, an arsRBCH operon was discovered in conjunction with the merRTPCADE operon, which provides mercury resistance. P. eucrina OB49 may be involved in an ecological alternative for heavy metal remediation and growth promotion of wheat grown in metal-polluted soils. Our results suggested the detection of mobile genetic elements that harbour the ars operon and the fluoride resistance genes adjacent to the mer operon.
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Affiliation(s)
- Abdelmalek Lekired
- Laboratory of Microorganisms and Active Biomolecules, MBA-LR03ES03, Faculty of Sciences of Tunis, University of Tunis El Manar, Tunis, Tunisia
| | - Hafsa Cherif-Silini
- Laboratory of Applied Microbiology, Department of Microbiology, Faculty of Natural and Life Sciences, Ferhat Abbas University, 19000, Setif, Algeria
| | - Allaoua Silini
- Laboratory of Applied Microbiology, Department of Microbiology, Faculty of Natural and Life Sciences, Ferhat Abbas University, 19000, Setif, Algeria
| | - Hamza Ben Yahia
- Laboratory of Microorganisms and Active Biomolecules, MBA-LR03ES03, Faculty of Sciences of Tunis, University of Tunis El Manar, Tunis, Tunisia
| | - Hadda-Imene Ouzari
- Laboratory of Microorganisms and Active Biomolecules, MBA-LR03ES03, Faculty of Sciences of Tunis, University of Tunis El Manar, Tunis, Tunisia.
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Uraguchi S, Ohshiro Y, Okuda M, Kawakami S, Yoneyama N, Tsuchiya Y, Nakamura R, Takanezawa Y, Kiyono M. Mesophyll specific expression of a bacterial mercury transporter-based vacuolar sequestration machinery sufficiently enhances mercury tolerance of Arabidopsis. FRONTIERS IN PLANT SCIENCE 2022; 13:986600. [PMID: 36035696 PMCID: PMC9412105 DOI: 10.3389/fpls.2022.986600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 07/26/2022] [Indexed: 06/15/2023]
Abstract
We aimed to efficiently enhance plant Hg(II) tolerance by the transgenic approach utilizing a bacterial mercury transporter MerC, an Arabidopsis mesophyll specific promoter pRBCS1A, and a vacuolar membrane targeting syntaxin AtVAM3/SYP22. We generated two independent homozygous Arabidopsis pRBCS1A-TCV lines expressing mT-Sapphire-MerC-AtVAM3 under the control of pRBCS1A. Quantitative RT-PCR showed that the transgene was expressed specifically in shoots of pRBCS1A-TCV lines. Confocal analyses further demonstrated the leaf mesophyll specific expression of mT-Sapphire-MerC-AtVAM3. Confocal observation of the protoplast derived from the F1 plants of the pRBCS1A-TCV line and the tonoplast marker line p35S-GFP-δTIP showed the tonoplast colocalization of mT-Sapphire-MerC-AtVAM3 and GFP-δTIP. These results clearly demonstrated that mT-Sapphire-MerC-AtVAM3 expression in Arabidopsis is spatially regulated as designed at the transcript and the membrane trafficking levels. We then examined the Hg(II) tolerance of the pRBCS1A-TCV lines as well as the p35S-driven MerC-AtVAM3 expressing line p35S-CV under the various Hg(II) stress conditions. Short-term (12 d) Hg(II) treatment indicated the enhanced Hg(II) tolerance of both pRBCS1A-TCV and p35S-CV lines. The longer (3 weeks) Hg(II) treatment highlighted the better shoot growth of the transgenic plants compared to the wild-type Col-0 and the pRBCS1A-TCV lines were more tolerant to Hg(II) stress than the p35S-CV line. These results suggest that mesophyll-specific expression of MerC-AtVAM3 is sufficient or even better to enhance the Arabidopsis Hg(II) tolerance. The Hg accumulation in roots and shoots did not differ between the wild-type Col-0 and the MerC-AtVAM3 expressing plants, suggesting that the boosted Hg(II) tolerance of the transgenic lines would be attributed to vacuolar Hg-sequestration by the tonoplast-localized MerC. Further perspectives of the MerC-based plant engineering are also discussed.
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