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Zhang Y, Ku YS, Cheung TY, Cheng SS, Xin D, Gombeau K, Cai Y, Lam HM, Chan TF. Challenges to rhizobial adaptability in a changing climate: Genetic engineering solutions for stress tolerance. Microbiol Res 2024; 288:127886. [PMID: 39232483 DOI: 10.1016/j.micres.2024.127886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2024] [Revised: 08/12/2024] [Accepted: 08/26/2024] [Indexed: 09/06/2024]
Abstract
Rhizobia interact with leguminous plants in the soil to form nitrogen fixing nodules in which rhizobia and plant cells coexist. Although there are emerging studies on rhizobium-associated nitrogen fixation in cereals, the legume-rhizobium interaction is more well-studied and usually serves as the model to study rhizobium-mediated nitrogen fixation in plants. Rhizobia play a crucial role in the nitrogen cycle in many ecosystems. However, rhizobia are highly sensitive to variations in soil conditions and physicochemical properties (i.e. moisture, temperature, salinity, pH, and oxygen availability). Such variations directly caused by global climate change are challenging the adaptive capabilities of rhizobia in both natural and agricultural environments. Although a few studies have identified rhizobial genes that confer adaptation to different environmental conditions, the genetic basis of rhizobial stress tolerance remains poorly understood. In this review, we highlight the importance of improving the survival of rhizobia in soil to enhance their symbiosis with plants, which can increase crop yields and facilitate the establishment of sustainable agricultural systems. To achieve this goal, we summarize the key challenges imposed by global climate change on rhizobium-plant symbiosis and collate current knowledge of stress tolerance-related genes and pathways in rhizobia. And finally, we present the latest genetic engineering approaches, such as synthetic biology, implemented to improve the adaptability of rhizobia to changing environmental conditions.
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Affiliation(s)
- Yunjia Zhang
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China; Centre for Soybean Research of the State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| | - Yee-Shan Ku
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China; Centre for Soybean Research of the State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| | - Tsz-Yan Cheung
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China; Centre for Soybean Research of the State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| | - Sau-Shan Cheng
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China; Centre for Soybean Research of the State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| | - Dawei Xin
- College of Agriculture, Northeast Agricultural University, Changjiang Road 600, Harbin 150030, China
| | - Kewin Gombeau
- Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Yizhi Cai
- Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Hon-Ming Lam
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China; Centre for Soybean Research of the State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China; Institute of Environment, Energy and Sustainability, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.
| | - Ting-Fung Chan
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China; Centre for Soybean Research of the State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China; Institute of Environment, Energy and Sustainability, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.
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Lundell S, Biligetu B. Differential gene expression of salt-tolerant alfalfa in response to salinity and inoculation by Ensifer meliloti. BMC PLANT BIOLOGY 2024; 24:633. [PMID: 38971752 PMCID: PMC11227210 DOI: 10.1186/s12870-024-05337-5] [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: 03/07/2024] [Accepted: 06/25/2024] [Indexed: 07/08/2024]
Abstract
BACKGROUND Alfalfa (Medicago sativa L.) experiences many negative effects under salinity stress, which may be mediated by recurrent selection. Salt-tolerant alfalfa may display unique adaptations in association with rhizobium under salt stress. RESULTS To elucidate inoculation effects on salt-tolerant alfalfa under salt stress, this study leveraged a salt-tolerant alfalfa population selected through two cycles of recurrent selection under high salt stress. After experiencing 120-day salt stress, mRNA was extracted from 8 random genotypes either grown in 0 or 8 dS/m salt stress with or without inoculation by Ensifer meliloti. Results showed 320 and 176 differentially expressed genes (DEGs) modulated in response to salinity stress or inoculation x salinity stress, respectively. Notable results in plants under 8 dS/m stress included upregulation of a key gene involved in the Target of Rapamycin (TOR) signaling pathway with a concomitant decrease in expression of the SNrK pathway. Inoculation of salt-stressed plants stimulated increased transcription of a sulfate-uptake gene as well as upregulation of the Lysine-27-trimethyltransferase (EZH2), Histone 3 (H3), and argonaute (AGO, a component of miRISC silencing complexes) genes related to epigenetic and post-transcriptional gene control. CONCLUSIONS Salt-tolerant alfalfa may benefit from improved activity of TOR and decreased activity of SNrK1 in salt stress, while inoculation by rhizobiumstimulates production of sulfate uptake- and other unique genes.
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Affiliation(s)
- Seth Lundell
- Department of Plant Sciences, College of Agriculture and Bio-Resources, University of Saskatchewan, 51 Campus Dr., Saskatoon, SK, S7N5A8, Canada
| | - Bill Biligetu
- Department of Plant Sciences, College of Agriculture and Bio-Resources, University of Saskatchewan, 51 Campus Dr., Saskatoon, SK, S7N5A8, Canada.
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Ben Gaied R, Sbissi I, Tarhouni M, Brígido C. Bacterial Endophytes from Legumes Native to Arid Environments Are Promising Tools to Improve Mesorhizobium-Chickpea Symbiosis under Salinity. BIOLOGY 2024; 13:96. [PMID: 38392314 PMCID: PMC10886315 DOI: 10.3390/biology13020096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 01/26/2024] [Accepted: 02/01/2024] [Indexed: 02/24/2024]
Abstract
Symbiotic nitrogen fixation is a major contributor of N in agricultural ecosystems, but the establishment of legume-rhizobium symbiosis is highly affected by soil salinity. Our interest is focused on the use of non-rhizobial endophytes to assist the symbiosis between chickpea and its microsymbiont under salinity to avoid loss of production and fertility. Our aims were (1) to investigate the impact of salinity on both symbiotic partners; including on early events of the Mesorhizobium-chickpea symbiosis, and (2) to evaluate the potential of four non-rhizobial endophytes isolated from legumes native to arid regions (Phyllobacterium salinisoli, P. ifriqiyense, Xanthomonas translucens, and Cupriavidus respiraculi) to promote chickpea growth and nodulation under salinity. Our results show a significant reduction in chickpea seed germination rate and in the microsymbiont Mesorhizobium ciceri LMS-1 growth under different levels of salinity. The composition of phenolic compounds in chickpea root exudates significantly changed when the plants were subjected to salinity, which in turn affected the nod genes expression in LMS-1. Furthermore, the LMS-1 response to root exudate stimuli was suppressed by the presence of salinity (250 mM NaCl). On the contrary, a significant upregulation of exoY and otsA genes, which are involved in exopolysaccharide and trehalose biosynthesis, respectively, was registered in salt-stressed LMS-1 cells. In addition, chickpea co-inoculation with LMS-1 along with the consortium containing two non-rhizobial bacterial endophytes, P. salinisoli and X. translucens, resulted in significant improvement of the chickpea growth and the symbiotic performance of LMS-1 under salinity. These results indicate that this non-rhizobial endophytic consortium may be an appropriate ecological and safe tool to improve chickpea growth and its adaptation to salt-degraded soils.
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Affiliation(s)
- Roukaya Ben Gaied
- Laboratory of Pastoral Ecosystems and Promotion of Spontaneous Plants and Associated Micro-Organisms, Institute of Arid Lands, University of Gabes, Medenine 4119, Tunisia
- MED-Mediterranean Institute for Agriculture, Environment and Development, Universidade de Évora, Pólo da Mitra, Ap. 94, 7006-554 Évora, Portugal
| | - Imed Sbissi
- Laboratory of Pastoral Ecosystems and Promotion of Spontaneous Plants and Associated Micro-Organisms, Institute of Arid Lands, University of Gabes, Medenine 4119, Tunisia
| | - Mohamed Tarhouni
- Laboratory of Pastoral Ecosystems and Promotion of Spontaneous Plants and Associated Micro-Organisms, Institute of Arid Lands, University of Gabes, Medenine 4119, Tunisia
| | - Clarisse Brígido
- MED-Mediterranean Institute for Agriculture, Environment and Development & CHANGE-Global Change and Sustainability Institute, Institute for Advanced Studies and Research, Universidade de Évora, Pólo da Mitra, Ap. 94, 7006-554 Évora, Portugal
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Zartdinova R, Nikitin A. Calcium in the Life Cycle of Legume Root Nodules. Indian J Microbiol 2023; 63:410-420. [PMID: 38031601 PMCID: PMC10682328 DOI: 10.1007/s12088-023-01107-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 10/07/2023] [Indexed: 12/01/2023] Open
Abstract
The present review highlights both the fundamental questions of calcium localization, compartmentation, and its participation in symbiosome signaling cascades during nodule formation and functioning. Apparently, the main link of such signaling is the calmodulin…calcium- and calmodulin-dependent protein kinases…CYCLOPS…NIN…target genes cascade. The minimum threshold level of calcium as a signaling agent in the presence of intracellular reserves determines the possibility of oligotrophy and ultraoligotrophy in relation to this element. During the functioning of root nodules, the Ca2+-ATPases activity maintains homeostasis of low calcium concentrations in the cytosol of nodule parenchyma cells. Disturbation of this homeostasis can trigger the root nodule senescence. The same reasons determine the increase in the effectiveness of symbiosis with the help of seed priming with sources of calcium. Examples of calcium response polymorphism in components of nitrogen fixing simbiosis important in practical terms are shown.
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Affiliation(s)
- Rozaliya Zartdinova
- Nitrogen Exchange Laboratory, Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, Russia
| | - Andrey Nikitin
- Nitrogen Exchange Laboratory, Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, Russia
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Abstract
Plants associate with nitrogen-fixing bacteria to secure nitrogen, which is generally the most limiting nutrient for plant growth. Endosymbiotic nitrogen-fixing associations are widespread among diverse plant lineages, ranging from microalgae to angiosperms, and are primarily one of three types: cyanobacterial, actinorhizal or rhizobial. The large overlap in the signaling pathways and infection components of arbuscular mycorrhizal, actinorhizal and rhizobial symbioses reflects their evolutionary relatedness. These beneficial associations are influenced by environmental factors and other microorganisms in the rhizosphere. In this review, we summarize the diversity of nitrogen-fixing symbioses, key signal transduction pathways and colonization mechanisms relevant to such interactions, and compare and contrast these interactions with arbuscular mycorrhizal associations from an evolutionary standpoint. Additionally, we highlight recent studies on environmental factors regulating nitrogen-fixing symbioses to provide insights into the adaptation of symbiotic plants to complex environments.
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Affiliation(s)
- Peng Xu
- National key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Ertao Wang
- National key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China; School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China; New Cornerstone Science Laboratory, Shenzhen 518054, China.
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Goyal RK, Habtewold JZ. Evaluation of Legume-Rhizobial Symbiotic Interactions Beyond Nitrogen Fixation That Help the Host Survival and Diversification in Hostile Environments. Microorganisms 2023; 11:1454. [PMID: 37374957 DOI: 10.3390/microorganisms11061454] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 05/26/2023] [Accepted: 05/29/2023] [Indexed: 06/29/2023] Open
Abstract
Plants often experience unfavorable conditions during their life cycle that impact their growth and sometimes their survival. A temporary phase of such stress, which can result from heavy metals, drought, salinity, or extremes of temperature or pH, can cause mild to enormous damage to the plant depending on its duration and intensity. Besides environmental stress, plants are the target of many microbial pathogens, causing diseases of varying severity. In plants that harbor mutualistic bacteria, stress can affect the symbiotic interaction and its outcome. To achieve the full potential of a symbiotic relationship between the host and rhizobia, it is important that the host plant maintains good growth characteristics and stay healthy under challenging environmental conditions. The host plant cannot provide good accommodation for the symbiont if it is infested with diseases and prone to other predators. Because the bacterium relies on metabolites for survival and multiplication, it is in its best interests to keep the host plant as stress-free as possible and to keep the supply stable. Although plants have developed many mitigation strategies to cope with stress, the symbiotic bacterium has developed the capability to augment the plant's defense mechanisms against environmental stress. They also provide the host with protection against certain diseases. The protective features of rhizobial-host interaction along with nitrogen fixation appear to have played a significant role in legume diversification. When considering a legume-rhizobial symbiosis, extra benefits to the host are sometimes overlooked in favor of the symbionts' nitrogen fixation efficiency. This review examines all of those additional considerations of a symbiotic interaction that enable the host to withstand a wide range of stresses, enabling plant survival under hostile regimes. In addition, the review focuses on the rhizosphere microbiome, which has emerged as a strong pillar of evolutionary reserve to equip the symbiotic interaction in the interests of both the rhizobia and host. The evaluation would draw the researchers' attention to the symbiotic relationship as being advantageous to the host plant as a whole and the role it plays in the plant's adaptation to unfavorable environmental conditions.
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Affiliation(s)
- Ravinder K Goyal
- Agriculture and Agri-Food Canada, Lacombe Research and Development Center, Lacombe, AB T4L 1W1, Canada
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Chakraborty S, Valdés-López O, Stonoha-Arther C, Ané JM. Transcription Factors Controlling the Rhizobium-Legume Symbiosis: Integrating Infection, Organogenesis and the Abiotic Environment. PLANT & CELL PHYSIOLOGY 2022; 63:1326-1343. [PMID: 35552446 DOI: 10.1093/pcp/pcac063] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 05/03/2022] [Accepted: 05/09/2022] [Indexed: 06/15/2023]
Abstract
Legume roots engage in a symbiotic relationship with rhizobia, leading to the development of nitrogen-fixing nodules. Nodule development is a sophisticated process and is under the tight regulation of the plant. The symbiosis initiates with a signal exchange between the two partners, followed by the development of a new organ colonized by rhizobia. Over two decades of study have shed light on the transcriptional regulation of rhizobium-legume symbiosis. A large number of transcription factors (TFs) have been implicated in one or more stages of this symbiosis. Legumes must monitor nodule development amidst a dynamic physical environment. Some environmental factors are conducive to nodulation, whereas others are stressful. The modulation of rhizobium-legume symbiosis by the abiotic environment adds another layer of complexity and is also transcriptionally regulated. Several symbiotic TFs act as integrators between symbiosis and the response to the abiotic environment. In this review, we trace the role of various TFs involved in rhizobium-legume symbiosis along its developmental route and highlight the ones that also act as communicators between this symbiosis and the response to the abiotic environment. Finally, we discuss contemporary approaches to study TF-target interactions in plants and probe their potential utility in the field of rhizobium-legume symbiosis.
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Affiliation(s)
- Sanhita Chakraborty
- Department of Bacteriology, University of Wisconsin, Microbial Sciences Building, 1550 Linden Dr, Madison, WI 53706, USA
| | - Oswaldo Valdés-López
- Laboratorio de Genómica Funcional de Leguminosas, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Tlalnepantla, Estado de México 54090, México
| | - Christina Stonoha-Arther
- Department of Bacteriology, University of Wisconsin, Microbial Sciences Building, 1550 Linden Dr, Madison, WI 53706, USA
| | - Jean-Michel Ané
- Department of Bacteriology, University of Wisconsin, Microbial Sciences Building, 1550 Linden Dr, Madison, WI 53706, USA
- Department of Agronomy, University of Wisconsin, 1575 Linden Dr, Madison, WI 53706, USA
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Acetylene reduction assay for nitrogenase activity in root nodules under salinity stress. Methods Enzymol 2022; 683:253-264. [PMID: 37087191 DOI: 10.1016/bs.mie.2022.08.044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Nitrogenase, an enzyme present in a select group of prokaryotes reduces inert N2 into NH3 that can be utilized through biological pathways. This process, termed biological nitrogen fixation, plays a crucial role in the biogeochemical N cycle. The ability of nitrogenase to reduce acetylene to ethylene has been exploited to develop a reliable and accessible biochemical assay to measure this enzyme's activity. Biological nitrogen fixation by rhizobia bacteria that occupy root nodules of legume crops is a major source of sustainable nitrogen nutrition in agriculture. Environmental stresses exacerbated by climate change necessitate the need to evaluate nitrogen fixation in root nodules under various stress conditions. Here, we provide a detailed step-by-step protocol for nitrogenase activity measurements using acetylene reduction assay in field pea plants under saline stress. The protocol can be easily adapted for use with other biological systems.
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