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Timofeeva AM, Galyamova MR, Sedykh SE. How Do Plant Growth-Promoting Bacteria Use Plant Hormones to Regulate Stress Reactions? PLANTS (BASEL, SWITZERLAND) 2024; 13:2371. [PMID: 39273855 PMCID: PMC11397614 DOI: 10.3390/plants13172371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2024] [Revised: 08/19/2024] [Accepted: 08/24/2024] [Indexed: 09/15/2024]
Abstract
Phytohormones play a crucial role in regulating growth, productivity, and development while also aiding in the response to diverse environmental changes, encompassing both biotic and abiotic factors. Phytohormone levels in soil and plant tissues are influenced by specific soil bacteria, leading to direct effects on plant growth, development, and stress tolerance. Specific plant growth-promoting bacteria can either synthesize or degrade specific plant phytohormones. Moreover, a wide range of volatile organic compounds synthesized by plant growth-promoting bacteria have been found to influence the expression of phytohormones. Bacteria-plant interactions become more significant under conditions of abiotic stress such as saline soils, drought, and heavy metal pollution. Phytohormones function in a synergistic or antagonistic manner rather than in isolation. The study of plant growth-promoting bacteria involves a range of approaches, such as identifying singular substances or hormones, comparing mutant and non-mutant bacterial strains, screening for individual gene presence, and utilizing omics approaches for analysis. Each approach uncovers the concealed aspects concerning the effects of plant growth-promoting bacteria on plants. Publications that prioritize the comprehensive examination of the private aspects of PGPB and cultivated plant interactions are of utmost significance and crucial for advancing the practical application of microbial biofertilizers. This review explores the potential of PGPB-plant interactions in promoting sustainable agriculture. We summarize the interactions, focusing on the mechanisms through which plant growth-promoting bacteria have a beneficial effect on plant growth and development via phytohormones, with particular emphasis on detecting the synthesis of phytohormones by plant growth-promoting bacteria.
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Affiliation(s)
- Anna M Timofeeva
- SB RAS Institute of Chemical Biology and Fundamental Medicine, 630090 Novosibirsk, Russia
- Faculty of Natural Sciences, Novosibirsk State University, 630090 Novosibirsk, Russia
| | - Maria R Galyamova
- Faculty of Natural Sciences, Novosibirsk State University, 630090 Novosibirsk, Russia
| | - Sergey E Sedykh
- SB RAS Institute of Chemical Biology and Fundamental Medicine, 630090 Novosibirsk, Russia
- Faculty of Natural Sciences, Novosibirsk State University, 630090 Novosibirsk, Russia
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2
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Fang M, Sun Y, Zhu Y, Chen Q, Chen Q, Liu Y, Zhang B, Chen T, Jin J, Yang T, Zhuang L. The potential of ferrihydrite-synthetic humic-like acid composite as a soil amendment for metal-contaminated agricultural soil: Immobilization mechanisms by combining abiotic and biotic perspectives. ENVIRONMENTAL RESEARCH 2024; 250:118470. [PMID: 38373548 DOI: 10.1016/j.envres.2024.118470] [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: 12/14/2023] [Revised: 02/02/2024] [Accepted: 02/10/2024] [Indexed: 02/21/2024]
Abstract
In-situ passivation technique has attracted increasing attention for metal-contaminated agricultural soil remediation. However, metal immobilization mechanisms are mostly illustrated based on metal speciation changes and alterations in soil physicochemical properties from a macroscopic and abiotic perspective. In this study, a ferrihydrite-synthetic humic-like acid composite (FH-SHLA) was fabricated and applied as a passivator for a 90-day soil incubation. The heavy metals immobilization mechanisms of FH-SHLA were investigated by combining both abiotic and biotic perspectives. Effects of FH-SHLA application on soil micro-ecology were also evaluated. The results showed that the 5%FH-SHLA treatment significantly decreased the DTPA-extractable Pb, Cd and Zn by 80.75%, 46.82% and 63.63% after 90 days of incubation (P < 0.05), respectively. Besides, 5% FH-SHLA addition significantly increased soil pH, soil organic matter content and cation exchange capacity (P < 0.05). The SEM, FTIR, and XPS characterizations revealed that the abiotic metal immobilization mechanisms by FH-SHLA included surface complexation, precipitation, electrostatic attraction, and cation-π interactions. For biotic perspective, in-situ microorganisms synergistically participated in the immobilization process via sulfide precipitation and Fe mineral production. FH-SHLA significantly altered the diversity and composition of the soil microbial community, and enhanced the intensity and complexity of the microbial co-occurrence network. Both metal bioavailability and soil physiochemical parameters played a vital role in shaping microbial communities, while the former contributed more. Overall, this study provides new insight into the heavy metal passivation mechanism and demonstrates that FH-SHLA is a promising and environmentally friendly amendment for metal-contaminated soil remediation.
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Affiliation(s)
- Mingzhi Fang
- College of Life and Environmental Sciences, Minzu University of China, Beijing, 100081, China
| | - Yucan Sun
- College of Life and Environmental Sciences, Minzu University of China, Beijing, 100081, China
| | - Yi Zhu
- College of Life and Environmental Sciences, Minzu University of China, Beijing, 100081, China
| | - Qi Chen
- College of Life and Environmental Sciences, Minzu University of China, Beijing, 100081, China
| | - Qianhui Chen
- College of Life and Environmental Sciences, Minzu University of China, Beijing, 100081, China
| | - Yifei Liu
- Technical Centre for Soil, Agriculture and Rural Ecology and Environment, Ministry of Ecology and Environment, Beijing, 100012, China
| | - Bing Zhang
- College of Life and Environmental Sciences, Minzu University of China, Beijing, 100081, China
| | - Tan Chen
- College of Life and Environmental Sciences, Minzu University of China, Beijing, 100081, China
| | - Jun Jin
- College of Life and Environmental Sciences, Minzu University of China, Beijing, 100081, China
| | - Ting Yang
- College of Life and Environmental Sciences, Minzu University of China, Beijing, 100081, China.
| | - Linlan Zhuang
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science & Engineering, Shandong University, Qingdao, 266237, China
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Hnamte L, Vanlallawmzuali, Kumar A, Yadav MK, Zothanpuia, Singh PK. An updated view of bacterial endophytes as antimicrobial agents against plant and human pathogens. CURRENT RESEARCH IN MICROBIAL SCIENCES 2024; 7:100241. [PMID: 39091295 PMCID: PMC11292266 DOI: 10.1016/j.crmicr.2024.100241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/04/2024] Open
Abstract
Bacterial endophytes are a crucial component of the phytomicrobiome, playing an essential role in agriculture and industries. Endophytes are a rich source of bioactive compounds, serving as natural antibiotics that can be effective in combating antibiotic resistance in pathogens. These bacteria interact with host plants through various processes such as quorum sensing, chemotaxis, antibiosis, and enzymatic activity. The current paper focuses on how plants benefit extensively from endophytic bacteria and their symbiotic relationship in which the microbes enhance plant growth, nitrogen fixation, increase nutrient uptake, improve defense mechanisms, and act as antimicrobial agents against pathogens. Moreover, it highlights some of the bioactive compounds produced by endophytes.
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Affiliation(s)
- Lalhmangaihmawia Hnamte
- Department of Biotechnology/Life Sciences, Pachhunga University College (A Constituent College of Mizoram University), Aizawl-796001, Mizoram, India
| | - Vanlallawmzuali
- Department of Biotechnology/Life Sciences, Pachhunga University College (A Constituent College of Mizoram University), Aizawl-796001, Mizoram, India
| | - Ajay Kumar
- Amity institute of Biotechnology, Amity University, Noida-201313, India
| | - Mukesh Kumar Yadav
- Department of Microbiology, Central University of Punjab, Bathinda, Punjab, India
| | - Zothanpuia
- Department of Biotechnology/Life Sciences, Pachhunga University College (A Constituent College of Mizoram University), Aizawl-796001, Mizoram, India
| | - Prashant Kumar Singh
- Department of Biotechnology/Life Sciences, Pachhunga University College (A Constituent College of Mizoram University), Aizawl-796001, Mizoram, India
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Xiao Y, Ma J, Chen R, Xiang S, Yang B, Chen L, Fang J, Liu S. Two microbes assisting Miscanthus floridulus in remediating multi-metal(loid)s-contaminated soil. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2024; 31:28922-28938. [PMID: 38565816 DOI: 10.1007/s11356-024-33032-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 03/18/2024] [Indexed: 04/04/2024]
Abstract
Miscanthus has good tolerance to multi-metal(loid)s and has received increasing attention in remediated studies of metal(loid)s-contaminated soil. In this study, we conducted phytoextraction techniques to investigate the synergic effects of remediation of multi-metal(loid)s-contaminated soil by Miscanthus floridulus (Lab.) and two plant growth-promoting bacteria (PGPB), TS8 and MR2, affiliated to Enterobacteriaceae. The results exhibited a decrease of arsenic (15.27-21.50%), cadmium (8.64-15.52%), plumbum (5.92-12.76%), and zinc (12.84-24.20%) except for copper contents in the soil in bacterial inoculation groups, indicating that MR2 and TS8 could enhance the remediation of metal(loid)s. Moreover, increased fresh/dry weight and height indicated that inoculated bacteria could promote Miscanthus growth. Although the activities of antioxidant enzymes and the content of chlorophyll in the overground tissues showed no significant increase or even decrease, the activities of antioxidant enzymes in the underground tissues and soil were elevated by 48.95-354.17%, available P by 19.07-23.02%, and available K by 15.34-17.79% (p < 0.05). Bacterial inoculants could also decrease the soil pH. High-throughput sequencing analysis showed that the bacterial inoculant affected the rhizosphere bacterial community and reduced community diversity, but the relative abundance of some PGPB was found to increase. Phylogenetic molecular ecological networks indicated that bacterial inoculants reduced interactions between rhizosphere bacteria and thereby led to a simpler network structure but increased the proportion of positive-correlation links and enhanced the metabiosis and symbiosis of those bacteria. Spearman's test showed that OTUs affiliated with Enterobacteriaceae and soil nutrients were critical for metal(loid) remediation and Miscanthus growth. The results of this study provide a basis for the synergic remediation of multi-metal(loid)s-contaminated soils by Miscanthus and PGPB and provide a reference for the subsequent regulation of Miscanthus remediation efficiency by the other PGPB or critical bacteria.
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Affiliation(s)
- Yunhua Xiao
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, 410128, China
| | - Jingjing Ma
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, 410128, China
| | - Rui Chen
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, 410128, China
| | - Sha Xiang
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, 410128, China
| | - Bo Yang
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, 410128, China
| | - Liang Chen
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, 410128, China
| | - Jun Fang
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, 410128, China
| | - Shuming Liu
- School of Resources and Environment, Yili Normal University, Yining, 835000, China.
- Key Laboratory of Pollutant Chemistry and Environmental Treatment, Yili Normal University, Yining, 835000, China.
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Fu X, Ma Y, Wang D, Zhan L, Guo Z, Fan K, Yang T, Chu H. Long-term chemical fertilization results in a loss of temporal dynamics of diazotrophic communities in the wheat rhizosphere. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 875:162663. [PMID: 36894087 DOI: 10.1016/j.scitotenv.2023.162663] [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: 12/21/2022] [Revised: 03/01/2023] [Accepted: 03/02/2023] [Indexed: 06/18/2023]
Abstract
Diazotrophs are potential bacterial biofertilizers with efficacy for plant nutrition, which convert atmospheric N2 into plant available nitrogen. Although they are known to respond strongly to fertilization, little is known about the temporal dynamics of diazotrophic communities throughout plant developmental under different fertilization regimes. In this study, we investigated diazotrophic communities in the wheat rhizosphere at four developmental stages under three long-term fertilization regimes: no fertilizer (Control), chemical NPK fertilizer only (NPK), and NPK fertilizer plus cow manure (NPKM). Fertilization regime had greater effect (explained of 54.9 %) on diazotrophic community structure than developmental stage (explained of 4.8 %). NPK fertilization decreased the diazotrophic diversity and abundance to one-third of the Control, although this was largely recovered by the addition of manure. Meanwhile, Control treatment resulted in significant variation in diazotrophic abundance, diversity, and community structure (P = 0.001) depending on the developmental stage, while the NPK fertilization resulted in the loss of temporal dynamics of the diazotrophic community (P = 0.330), which could be largely recovered by the addition of manure (P = 0.011). Keystone species identified in this study were quite different among the four developmental stages under Control and NPKM treatment but were similar among stages under NPK treatment. These findings suggest that long-term chemical fertilization not only reduces diazotrophic diversity and abundance, but also results in a loss of temporal dynamics of rhizosphere diazotrophic communities.
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Affiliation(s)
- Xiao Fu
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, 71 East Beijing Road, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuying Ma
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, 71 East Beijing Road, Nanjing 210008, China
| | - Daozhong Wang
- Key Laboratory of Nutrient Cycling and Resources Environment of Anhui Province, Soil and Fertilizer Research Institute, Anhui Academy of Agricultural Sciences, 40 South Nongke Road, Hefei 230001, China
| | - Linchuan Zhan
- Key Laboratory of Nutrient Cycling and Resources Environment of Anhui Province, Soil and Fertilizer Research Institute, Anhui Academy of Agricultural Sciences, 40 South Nongke Road, Hefei 230001, China
| | - Zhibin Guo
- Key Laboratory of Nutrient Cycling and Resources Environment of Anhui Province, Soil and Fertilizer Research Institute, Anhui Academy of Agricultural Sciences, 40 South Nongke Road, Hefei 230001, China
| | - Kunkun Fan
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, 71 East Beijing Road, Nanjing 210008, China
| | - Teng Yang
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, 71 East Beijing Road, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Haiyan Chu
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, 71 East Beijing Road, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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6
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Jin X, Rahman MKU, Ma C, Zheng X, Wu F, Zhou X. Silicon modification improves biochar's ability to mitigate cadmium toxicity in tomato by enhancing root colonization of plant-beneficial bacteria. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2023; 249:114407. [PMID: 36508786 DOI: 10.1016/j.ecoenv.2022.114407] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 11/16/2022] [Accepted: 12/07/2022] [Indexed: 06/17/2023]
Abstract
Modification of biochar, such as impregnation with minerals, can improve biochar's efficacy to mitigate heavy metal toxicity in plants. Biochar amendments can alter plant rhizosphere microbiome, which has profound effects on plant growth and fitness. Here, we tested whether rhizosphere microbiome is involved in the ability of silicon (Si)-modified biochar to mitigate cadmium toxicity in tomato (Solanum lycopersicum L.). We demonstrated that Si modification altered biochar's physico-chemical properties and enhanced its ability to mitigate cadmium toxicity in tomato. Particularly, the Si-modified biochar contained higher content of Si and increased plant-available Si content in the soil. The rhizosphere microbiome transplant experiment showed that changes in rhizosphere microbiome contributed to the mitigation of cadmium toxicity by biochar amendments. The raw biochar and Si-modified biochar differently altered tomato rhizosphere bacterial community composition. Both biochars, especially the Si-modified biochar, promoted specific bacterial taxa (e.g., Sphingomonas, Lysobacter and Pseudomonas spp.). Subsequent culturing found these promoted bacteria could mitigate cadmium toxicity in tomato. Moreover, both biochars stimulated tomato to recruit plant-beneficial bacteria with Si-modified biochar having stronger stimulatory effects, indicating that the positive effects of biochar on plant-beneficial bacteria was partially mediated via the host plant. Overall, Si modification enhanced biochar's ability to mitigate cadmium toxicity, which was linked to the stimulatory effects on plant-beneficial bacteria.
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Affiliation(s)
- Xue Jin
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Northeast Region), Ministry of Agriculture and Rural Affairs, Department of Horticulture, Northeast Agricultural University, Harbin 150030, China
| | - Muhammad Khashi U Rahman
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Northeast Region), Ministry of Agriculture and Rural Affairs, Department of Horticulture, Northeast Agricultural University, Harbin 150030, China
| | - Changli Ma
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Northeast Region), Ministry of Agriculture and Rural Affairs, Department of Horticulture, Northeast Agricultural University, Harbin 150030, China
| | - Xianqing Zheng
- Institute of Eco-Environment and Plant Protection, Shanghai Academy of Agricultural Sciences, Shanghai 201403, China
| | - Fengzhi Wu
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Northeast Region), Ministry of Agriculture and Rural Affairs, Department of Horticulture, Northeast Agricultural University, Harbin 150030, China
| | - Xingang Zhou
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Northeast Region), Ministry of Agriculture and Rural Affairs, Department of Horticulture, Northeast Agricultural University, Harbin 150030, China.
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7
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Alonso‐Fernandes E, Fernández‐Llamosas H, Cano I, Serrano‐Pelejero C, Castro L, Díaz E, Carmona M. Enhancing tellurite and selenite bioconversions by overexpressing a methyltransferase from
Aromatoleum
sp. CIB. Microb Biotechnol 2022; 16:915-930. [PMID: 36366868 PMCID: PMC10128142 DOI: 10.1111/1751-7915.14162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 09/21/2022] [Accepted: 10/09/2022] [Indexed: 11/13/2022] Open
Abstract
Pollution by metalloids, e.g., tellurite and selenite, is of serious environmental concern and, therefore, there is an increasing interest in searching for ecologically friendly solutions for their elimination. Some microorganisms are able to reduce toxic tellurite/selenite into less toxic elemental tellurium (Te) and selenium (Se). Here, we describe the use of the environmentally relevant β-proteobacterium Aromatoleum sp. CIB as a platform for tellurite elimination. Aromatoleum sp. CIB was shown to tolerate 0.2 and 0.5 mM tellurite at aerobic and anaerobic conditions, respectively. Furthermore, the CIB strain was able to reduce tellurite into elemental Te producing rod-shaped Te nanoparticles (TeNPs) of around 200 nm length. A search in the genome of Aromatoleum sp. CIB revealed the presence of a gene, AzCIB_0135, which encodes a new methyltransferase that methylates tellurite and also selenite. AzCIB_0135 orthologs are widely distributed in bacterial genomes. The overexpression of the AzCIB_0135 gene both in Escherichia coli and Aromatoleum sp. CIB speeds up tellurite and selenite removal, and it enhances the production of rod-shaped TeNPs and spherical Se nanoparticles (SeNPs), respectively. Thus, the overexpression of a methylase becomes a new genetic strategy to optimize bacterial catalysts for tellurite/selenite bioremediation and for the programmed biosynthesis of metallic nanoparticles of biotechnological interest.
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Affiliation(s)
- Elena Alonso‐Fernandes
- Microbial and Plant Biotechnology Department Centro de Investigaciones Biológicas Margarita Salas‐CSIC Madrid Spain
| | - Helga Fernández‐Llamosas
- Microbial and Plant Biotechnology Department Centro de Investigaciones Biológicas Margarita Salas‐CSIC Madrid Spain
| | - Irene Cano
- Microbial and Plant Biotechnology Department Centro de Investigaciones Biológicas Margarita Salas‐CSIC Madrid Spain
| | - Cristina Serrano‐Pelejero
- Microbial and Plant Biotechnology Department Centro de Investigaciones Biológicas Margarita Salas‐CSIC Madrid Spain
| | - Laura Castro
- Department of Material Science and Metallurgical Engineering, Facultad de Químicas Universidad Complutense de Madrid Madrid Spain
| | - Eduardo Díaz
- Microbial and Plant Biotechnology Department Centro de Investigaciones Biológicas Margarita Salas‐CSIC Madrid Spain
| | - Manuel Carmona
- Microbial and Plant Biotechnology Department Centro de Investigaciones Biológicas Margarita Salas‐CSIC Madrid Spain
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Tian Z, Chen Y, Chen S, Yan D, Wang X, Guo Y. AcdS gene of Bacillus cereus enhances salt tolerance of seedlings in tobacco ( Nicotiana tabacum L.). BIOTECHNOL BIOTEC EQ 2022. [DOI: 10.1080/13102818.2022.2144450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- Zengyuan Tian
- School of Agricultural Sciences, Zhengzhou University, Zhengzhou, Henan, PR China
| | - Yange Chen
- School of Agricultural Sciences, Zhengzhou University, Zhengzhou, Henan, PR China
| | - Shuai Chen
- School of Life Sciences, Zhengzhou University, Zhengzhou, Henan, PR China
| | - Daoliang Yan
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou, PR China
| | - Xiaoming Wang
- School of Life Sciences, Zhengzhou University, Zhengzhou, Henan, PR China
| | - Yuqi Guo
- School of Life Sciences, Zhengzhou University, Zhengzhou, Henan, PR China
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9
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Ganie SA, Bhat JA, Devoto A. The influence of endophytes on rice fitness under environmental stresses. PLANT MOLECULAR BIOLOGY 2022; 109:447-467. [PMID: 34859329 PMCID: PMC9213282 DOI: 10.1007/s11103-021-01219-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 11/08/2021] [Indexed: 05/26/2023]
Abstract
KEY MESSAGE Endophytes are crucial for the promotion of rice growth and stress tolerance and can be used to increase rice crop yield. Endophytes can thus be exploited in biotechnology and genetic engineering as eco-friendly and cost-effective means for the development of high-yielding and stress-tolerant rice plants. Rice (Oryza sativa) crop is continuously subjected to biotic and abiotic stresses, compromising growth and consequently yield. The situation is exacerbated by climate change impacting on ecosystems and biodiversity. Genetic engineering has been used to develop stress-tolerant rice, alongside physical and chemical methods to mitigate the effect of these stresses. However, the success of these strategies has been hindered by short-lived field success and public concern on adverse effects associated. The limited success in the field of stress-tolerant cultivars developed through breeding or transgenic approaches is due to the complex nature of stress tolerance as well as to the resistance breakdown caused by accelerated evolution of pathogens. It is therefore necessary to develop novel and acceptable strategies to enhance rice stress tolerance and durable resistance and consequently improve yield. In the last decade, plant growth promoting (PGP) microbes, especially endophytes, have drawn the attention of agricultural scientists worldwide, due to their ability to mitigate environmental stresses in crops, without causing adverse effects. Increasing evidence indicates that endophytes effectively confer fitness benefits also to rice under biotic and abiotic stress conditions. Endophyte-produced metabolites can control the expression of stress-responsive genes and improve the physiological performance and growth of rice plants. This review highlights the current evidence available for PGP microbe-promoted tolerance of rice to abiotic stresses such as salinity and drought and to biotic ones, with special emphasis on endophytes. Associated molecular mechanisms are illustrated, and prospects for sustainable rice production also in the light of the impending climate change, discussed.
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Affiliation(s)
- Showkat Ahmad Ganie
- Plant Molecular Science and Centre of Systems and Synthetic Biology, Department of Biological Sciences, Royal Holloway University of London, Egham, Surrey, TW20 0EX, UK
| | - Javaid Akhter Bhat
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, College of Agriculture, Nanjing Agricultural University, Nanjing, 210095, China.
| | - Alessandra Devoto
- Plant Molecular Science and Centre of Systems and Synthetic Biology, Department of Biological Sciences, Royal Holloway University of London, Egham, Surrey, TW20 0EX, UK.
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10
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Rabêlo FHS, Vangronsveld J, Baker AJM, van der Ent A, Alleoni LRF. Are Grasses Really Useful for the Phytoremediation of Potentially Toxic Trace Elements? A Review. FRONTIERS IN PLANT SCIENCE 2021; 12:778275. [PMID: 34917111 PMCID: PMC8670575 DOI: 10.3389/fpls.2021.778275] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 10/19/2021] [Indexed: 05/27/2023]
Abstract
The pollution of soil, water, and air by potentially toxic trace elements poses risks to environmental and human health. For this reason, many chemical, physical, and biological processes of remediation have been developed to reduce the (available) trace element concentrations in the environment. Among those technologies, phytoremediation is an environmentally friendly in situ and cost-effective approach to remediate sites with low-to-moderate pollution with trace elements. However, not all species have the potential to be used for phytoremediation of trace element-polluted sites due to their morpho-physiological characteristics and low tolerance to toxicity induced by the trace elements. Grasses are prospective candidates due to their high biomass yields, fast growth, adaptations to infertile soils, and successive shoot regrowth after harvest. A large number of studies evaluating the processes related to the uptake, transport, accumulation, and toxicity of trace elements in grasses assessed for phytoremediation have been conducted. The aim of this review is (i) to synthesize the available information on the mechanisms involved in uptake, transport, accumulation, toxicity, and tolerance to trace elements in grasses; (ii) to identify suitable grasses for trace element phytoextraction, phytostabilization, and phytofiltration; (iii) to describe the main strategies used to improve trace element phytoremediation efficiency by grasses; and (iv) to point out the advantages, disadvantages, and perspectives for the use of grasses for phytoremediation of trace element-polluted soils.
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Affiliation(s)
| | - Jaco Vangronsveld
- Centre for Environmental Sciences, Hasselt University, Diepenbeek, Belgium
- Department of Plant Physiology and Biophysics, Maria Curie-Skłodowska University, Lublin, Poland
| | - Alan J. M. Baker
- Centre for Mined Land Rehabilitation, Sustainable Minerals Institute, The University of Queensland, Brisbane, QLD, Australia
- School of BioSciences, The University of Melbourne, Parkville, VIC, Australia
- Laboratoire Sols et Environnement, Université de Lorraine – INRAE, Nancy, France
| | - Antony van der Ent
- Centre for Mined Land Rehabilitation, Sustainable Minerals Institute, The University of Queensland, Brisbane, QLD, Australia
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11
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Fernández-Llamosas H, Díaz E, Carmona M. Motility, Adhesion and c-di-GMP Influence the Endophytic Colonization of Rice by Azoarcus sp. CIB. Microorganisms 2021; 9:microorganisms9030554. [PMID: 33800326 PMCID: PMC7998248 DOI: 10.3390/microorganisms9030554] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 02/18/2021] [Accepted: 03/05/2021] [Indexed: 01/26/2023] Open
Abstract
Proficient crop production is needed to ensure the feeding of a growing global population. The association of bacteria with plants plays an important role in the health state of the plants contributing to the increase of agricultural production. Endophytic bacteria are ubiquitous in most plant species providing, in most cases, plant promotion properties. However, the knowledge on the genetic determinants involved in the colonization of plants by endophytic bacteria is still poorly understood. In this work we have used a genetic approach based on the construction of fliM, pilX and eps knockout mutants to show that the motility mediated by a functional flagellum and the pili type IV, and the adhesion modulated by exopolysaccarides are required for the efficient colonization of rice roots by the endophyte Azoarcus sp. CIB. Moreover, we have demonstrated that expression of an exogenous diguanylate cyclase or phophodiesterase, which causes either an increase or decrease of the intracellular levels of the second messenger cyclic di-GMP (c-di-GMP), respectively, leads to a reduction of the ability of Azoarcus sp. CIB to colonize rice plants. Here we present results demonstrating the unprecedented role of the universal second messenger cyclic-di-GMP in plant colonization by an endophytic bacterium, Azoarcus sp. CIB. These studies pave the way to further strategies to modulate the interaction of endophytes with their target plant hosts.
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Comparative Genomics Provides Insights into the Taxonomy of Azoarcus and Reveals Separate Origins of Nif Genes in the Proposed Azoarcus and Aromatoleum Genera. Genes (Basel) 2021; 12:genes12010071. [PMID: 33430351 PMCID: PMC7825797 DOI: 10.3390/genes12010071] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 12/30/2020] [Accepted: 01/05/2021] [Indexed: 01/19/2023] Open
Abstract
Among other attributes, the Betaproteobacterial genus Azoarcus has biotechnological importance for plant growth-promotion and remediation of petroleum waste-polluted water and soils. It comprises at least two phylogenetically distinct groups. The "plant-associated" group includes strains that are isolated from the rhizosphere or root interior of the C4 plant Kallar Grass, but also strains from soil and/or water; all are considered to be obligate aerobes and all are diazotrophic. The other group (now partly incorporated into the new genus Aromatoleum) comprises a diverse range of species and strains that live in water or soil that is contaminated with petroleum and/or aromatic compounds; all are facultative or obligate anaerobes. Some are diazotrophs. A comparative genome analysis of 32 genomes from 30 Azoarcus-Aromatoleum strains was performed in order to delineate generic boundaries more precisely than the single gene, 16S rRNA, that has been commonly used in bacterial taxonomy. The origin of diazotrophy in Azoarcus-Aromatoleum was also investigated by comparing full-length sequences of nif genes, and by physiological measurements of nitrogenase activity using the acetylene reduction assay. Based on average nucleotide identity (ANI) and whole genome analyses, three major groups could be discerned: (i) Azoarcus comprising Az. communis, Az. indigens and Az. olearius, and two unnamed species complexes, (ii) Aromatoleum Group 1 comprising Ar. anaerobium, Ar. aromaticum, Ar. bremense, and Ar. buckelii, and (iii) Aromatoleum Group 2 comprising Ar. diolicum, Ar. evansii, Ar. petrolei, Ar. toluclasticum, Ar. tolulyticum, Ar. toluolicum, and Ar. toluvorans. Single strain lineages such as Azoarcus sp. KH32C, Az. pumilus, and Az. taiwanensis were also revealed. Full length sequences of nif-cluster genes revealed two groups of diazotrophs in Azoarcus-Aromatoleum with nif being derived from Dechloromonas in Azoarcus sensu stricto (and two Thauera strains) and from Azospira in Aromatoleum Group 2. Diazotrophy was confirmed in several strains, and for the first time in Az. communis LMG5514, Azoarcus sp. TTM-91 and Ar. toluolicum TT. In terms of ecology, with the exception of a few plant-associated strains in Azoarcus (s.s.), across the group, most strains/species are found in soil and water (often contaminated with petroleum or related aromatic compounds), sewage sludge, and seawater. The possession of nar, nap, nir, nor, and nos genes by most Azoarcus-Aromatoleum strains suggests that they have the potential to derive energy through anaerobic nitrate respiration, so this ability cannot be usefully used as a phenotypic marker to distinguish genera. However, the possession of bzd genes indicating the ability to degrade benzoate anaerobically plus the type of diazotrophy (aerobic vs. anaerobic) could, after confirmation of their functionality, be considered as distinguishing phenotypes in any new generic delineations. The taxonomy of the Azoarcus-Aromatoleum group should be revisited; retaining the generic name Azoarcus for its entirety, or creating additional genera are both possible outcomes.
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