scholarly journals The legume-rhizobia symbiosis can be supported on Mars soil simulants

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0259957
Author(s):  
Randall Rainwater ◽  
Arijit Mukherjee
Keyword(s):  
Nitrogen Fixation ◽  
Sinorhizobium Meliloti ◽  
Root Nodules ◽  
Lateral Roots ◽  
Model Legume ◽  
Mars Atmosphere ◽  
Future Studies ◽  
Sinorhizobium Medicae ◽  
Total Plant ◽  
Atmospheric Nitrogen Fixation

Legumes (soybeans, peas, lentils, etc.) play important roles in agriculture on Earth because of their food value and their ability to form a mutualistic beneficial association with rhizobia bacteria. In this association, the host plant benefits from atmospheric nitrogen fixation by rhizobia. The presence of nitrogen in the Mars atmosphere offers the possibility to take advantage of this important plant-microbe association. While some studies have shown that Mars soil simulants can support plant growth, none have investigated if these soils can support the legume-rhizobia symbiosis. In this study, we investigated the establishment of the legume-rhizobia symbiosis on different Mars soil simulants (different grades of the Mojave Mars Simulant (MMS)-1: Coarse, Fine, Unsorted, Superfine, and the MMS-2 simulant). We used the model legume, Medicago truncatula, and its symbiotic partners, Sinorhizobium meliloti and Sinorhizobium medicae, in these experiments. Our results show that root nodules could develop on M. truncatula roots when grown on these Mars soil simulants and were comparable to those formed on plants that were grown on sand. We also detected nifH (a reporter gene for nitrogen fixation) expression inside these nodules. Our results indicate that the different Mars soil simulants used in this study can support legume-rhizobia symbiosis. While the average number of lateral roots and nodule numbers were comparable on plants grown on the different soil simulants, total plant mass was higher in plants grown on MMS-2 soil than on MMS-1 soil and its variants. Our results imply that the chemical composition of the simulants is more critical than their grain size for plant mass. Based on these results, we recommend that the MMS-2 Superfine soil simulant is a better fit than the MMS-1 soil and it’s variants for future studies. Our findings can serve as an excellent resource for future studies investigating beneficial plant-microbe associations for sustainable agriculture on Mars.

scholarly journals Sinorhizobium meliloti Controls Nitric Oxide–Mediated Post-Translational Modification of a Medicago truncatula Nodule Protein

2015 ◽  
Vol 28 (12) ◽  
pp. 1353-1363 ◽  
Author(s):  
Pauline Blanquet ◽  
Liliana Silva ◽  
Olivier Catrice ◽  
Claude Bruand ◽  
Helena Carvalho ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitrogen Fixation ◽  
Medicago Truncatula ◽  
Sinorhizobium Meliloti ◽  
Molecular Mechanisms ◽  
Root Nodules ◽  
Plant Protein ◽  
Post Translational Modification ◽  
Model Legume ◽  
Bacterial Mutants

Nitric oxide (NO) is involved in various plant-microbe interactions. In the symbiosis between soil bacterium Sinorhizobium meliloti and model legume Medicago truncatula, NO is required for an optimal establishment of the interaction but is also a signal for nodule senescence. Little is known about the molecular mechanisms responsible for NO effects in the legume-rhizobium interaction. Here, we investigate the contribution of the bacterial NO response to the modulation of a plant protein post-translational modification in nitrogen-fixing nodules. We made use of different bacterial mutants to finely modulate NO levels inside M. truncatula root nodules and to examine the consequence on tyrosine nitration of the plant glutamine synthetase, a protein responsible for assimilation of the ammonia released by nitrogen fixation. Our results reveal that S. meliloti possesses several proteins that limit inactivation of plant enzyme activity via NO-mediated post-translational modifications. This is the first demonstration that rhizobia can impact the course of nitrogen fixation by modulating the activity of a plant protein.

scholarly journals The LATD Gene of Medicago truncatula Is Required for Both Nodule and Root Development

2005 ◽  
Vol 18 (6) ◽  
pp. 521-532 ◽  
Author(s):  
Lydia J. Bright ◽  
Yan Liang ◽  
David M. Mitchell ◽  
Jeanne M. Harris
Keyword(s):  
Medicago Truncatula ◽  
Root Development ◽  
Sinorhizobium Meliloti ◽  
Root Nodules ◽  
Lateral Roots ◽  
Primary Root ◽  
Evolutionary Origin ◽  
Nodule Formation ◽  
Wild Type ◽  
Model Legume

The evolutionary origins of legume root nodules are largely unknown. We have identified a gene,LATD, of the model legume Medicago truncatula, that is required for both nodule and root development, suggesting that these two developmental processes may share a common evolutionary origin. The latd mutant plants initiate nodule formation but do not complete it, resulting in immature, non-nitrogen-fixing nodules. Similarly, lateral roots initiate, but remain shortstumps. The primary root, which initially appears to be wild type, gradually ceases growth and forms an abnormal tipthat resembles that of the mutant lateral roots. Infection by the rhizobial partner, Sinorhizobium meliloti, can occur, although infection is rarely completed. Once inside latd mutant nodules, S. meliloti fails to express rhizobial genes associatedwith the developmental transition from free-living bacterium to endosymbiont, such as bacA and nex38. The infecting rhizobia also fail to express nifH and fix nitrogen. Thus, both plant and bacterial development are blocked in latd mutant roots. Based on the latd mutant phenotype, we propose that the wild-type function of the LATD gene is to maintain root meristems. The strong requirement of both nodules and lateral roots for wild-type LATD gene function supports lateral roots as a possible evolutionary origin for legume nodules.

scholarly journals Mutation in the ntrR Gene, a Member of the vap Gene Family, Increases the Symbiotic Efficiency of Sinorhizobium meliloti

2001 ◽  
Vol 14 (7) ◽  
pp. 887-894 ◽  
Author(s):  
Boglárka Oláh ◽  
Erno Kiss ◽  
Zoltán Györgypál ◽  
Judit Borzi ◽  
Gyöngyi Cinege ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Pathogenic Bacteria ◽  
Sinorhizobium Meliloti ◽  
Root Nodules ◽  
Nifh Gene ◽  
Dry Weight ◽  
Nodule Occupancy ◽  
Gene Encoding ◽  
Symbiotic Efficiency ◽  
Host Interactions

In specific plant organs, namely the root nodules of alfalfa, fixed nitrogen (ammonia) produced by the symbiotic partner Sinorhizobium meliloti supports the growth of the host plant in nitrogen-depleted environment. Here, we report that a derivative of S. meliloti carrying a mutation in the chromosomal ntrR gene induced nodules with enhanced nitrogen fixation capacity, resulting in an increased dry weight and nitrogen content of alfalfa. The efficient nitrogen fixation is a result of the higher expression level of the nifH gene, encoding one of the subunits of the nitrogenase enzyme, and nifA, the transcriptional regulator of the nif operon. The ntrR gene, controlled negatively by its own product and positively by the symbiotic regulator syrM, is expressed in the same zone of nodules as the nif genes. As a result of the nitrogen-tolerant phenotype of the strain, the beneficial effect of the mutation on efficiency is not abolished in the presence of the exogenous nitrogen source. The ntrR mutant is highly competitive in nodule occupancy compared with the wild-type strain. Sequence analysis of the mutant region revealed a new cluster of genes, termed the “ntrPR operon,” which is highly homologous to a group of vap-related genes of various pathogenic bacteria that are presumably implicated in bacterium-host interactions. On the basis of its favorable properties, the strain is a good candidate for future agricultural utilization.

scholarly journals The reaction of self-fertile alfalfa lines to inoculation with nodule bacteria

2020 ◽  
Keyword(s):  
Nitrogen Fixation ◽  
Sinorhizobium Meliloti ◽  
Root Nodules ◽  
Growing Season ◽  
Dry Mass ◽  
Nodule Bacteria ◽  
Forage Crop ◽  
Nitrogen Fixation Activity ◽  
Fixation Activity ◽  
Different Strains

Under the conditions of a model pot experiments, the reaction of the self-fertile lines of alfalfa Kishvardy 46, Kishvardy 27, Vertus and Ziguen to inoculation with nodule bacteria Sinorhizobium meliloti AC48 and AC88 was studied. As a result of studies, it was found that the intensity of assimilation of N2 by symbiotic systems created with the participation of various genotypes of alfalfa and active strains of S. meliloti is one of the main factors that affects the vegetative mass yield of this important forage crop. Self-fertile lines of Medicago sativa L. plants, inoculated with different strains of rhizobia were characterized by higher rates of the mass formed on the root nodules, compared to the control plants of the alfalfa variety Yaroslavna. The traditional dynamics of nitrogen-fixation activity of root nodules was maintained in all the symbiotic systems studied by us, with low values in the stems formation stage and intensive growth in the budding and flowering stages. The highest level of nitrogen fixation and vegetative growth of plants (values of plants green and dry mass, roots and root nodules mass) was established by inoculation of alfalfa line Kishvardy 46 with strain S. meliloti AC48. During the growing season the indices of the mass of nodules formed on the roots of these plants were higher by 1.8–2.3 times, the green mass by 1.2–1.6 times and the height of the plants 1.2–1.4 times as compared to the control. In the flowering stages the nitrogen-fixation activity of the symbiotic complex of plants of the Kishvardy line 27 and nodule bacteria S. meliloti AC48 exceeded the values in the symbiotic systems formed with the participation of the same strain and plants of the Ziguen and Vertus lines by 13.0 and 39.4 %. The lowest values of nitrogen fixation activity were observed by inoculation of plants of the Vertus and Ziguen lines with active strains S. meliloti AC48 and AC88 compared to the symbioses formed by the plants of the Kishvardy lines 27 and 46, as well as of the control-variety Yaroslavna with the noted strains. A stimulating effect of inoculation of alfalfa seeds of different genotypes on the growth and development of plants was noted, as evidenced by the positive dynamics of the increase in above-ground mass, the accumulation of dry matter and higher than the control values (indicators) of plant height during the growing season.

The occurrence and ontogeny of transfer cells associated with lateral roots and root nodules in Leguminosae

1979 ◽  
Vol 57 (23) ◽  
pp. 2583-2602 ◽  
Author(s):  
William Newcomb ◽  
R. L. Peterson
Keyword(s):  
Nitrogen Fixation ◽  
Rhizobium Leguminosarum ◽  
Root Nodules ◽  
Lateral Roots ◽  
Transfer Cells ◽  
Xylem Parenchyma ◽  
Cortical Cells ◽  
Nitrogenous Compounds ◽  
Wall Ingrowths ◽  
Xylem Elements

Xylem parenchyma transfer cells are present in the stele of the root tissue adjacent to emergent effective root nodules of garden pea (Pisum sativum), red kidney bean (Phaseolus vulgaris), broad bean (Vicia faba), soybean (Glycine max), and mung bean (Vigna radiata), two types of ineffective pea nodules, and emergent lateral roots of pea. The xylem parenchyma transfer cells contain many polyribosomes and mitochondria near the wall ingrowths which are located adjacent to pits in the xylem elements. Pericycle transfer cells also occur in the three types of pea nodules. In effective pea nodules wall ingrowths begin to form in the pericycle cells 5 days after inoculation with Rhizobium leguminosarum; at this stage rhizobia are only present in the root hair but the cortical cells have enlarged and some have undergone mitosis. The wall ingrowths begin to form in the xylem parenchyma cells 7–8 days after inoculation or the approximate time that rhizobia begin to be released from the infection thread. In both instances the wall ingrowths begin to form before the onset of dinitrogen reduction although previous workers have suggested that a flux of nitrogenous compounds (containing fixed N) induces their formation. The development of wall ingrowths in ineffective pea nodules also occurs independently of nitrogen fixation. Similarly, the wall ingrowths located near soybean nodules also begin to develop before the onset of nitrogen fixation.

scholarly journals Effects of Engineered Sinorhizobium meliloti on Cytokinin Synthesis and Tolerance of Alfalfa to Extreme Drought Stress

2012 ◽  
Vol 78 (22) ◽  
pp. 8056-8061 ◽  
Author(s):  
Ji Xu ◽  
Xiao-Lin Li ◽  
Li Luo
Keyword(s):  
Nitrogen Fixation ◽  
Drought Stress ◽  
Sinorhizobium Meliloti ◽  
Nitrogenase Activity ◽  
Root Nodules ◽  
Severe Drought ◽  
Control Strain ◽  
Free Living ◽  
Content Type ◽  
Host Tolerance

ABSTRACTCytokinin is required for the initiation of leguminous nitrogen fixation nodules elicited by rhizobia and the delay of the leaf senescence induced by drought stress. A few free-living rhizobia have been found to produce cytokinin. However, the effects of engineered rhizobia capable of synthesizing cytokinin on host tolerance to abiotic stresses have not yet been described. In this study, two engineeredSinorhizobiumstrains overproducing cytokinin were constructed. The tolerance of inoculated alfalfa plants to severe drought stress was assessed. The engineered strains, which expressed theAgrobacterium iptgene under the control of different promoters, synthesized more zeatins than the control strain under free-living conditions, but their own growth was not affected. After a 4-week inoculation period, the effects of engineered strains on alfalfa growth and nitrogen fixation were similar to those of the control strain under nondrought conditions. After being subjected to severe drought stress, most of the alfalfa plants inoculated with engineered strains survived, and the nitrogenase activity in their root nodules showed no apparent change. A small elevation in zeatin concentration was observed in the leaves of these plants. The expression of antioxidant enzymes increased, and the level of reactive oxygen species decreased correspondingly. Although theiptgene was transcribed in the bacteroids of engineered strains, the level of cytokinin in alfalfa nodules was identical to that of the control. These findings suggest that engineeredSinorhizobiumstrains synthesizing more cytokinin could improve the tolerance of alfalfa to severe drought stress without affecting alfalfa nodulation or nitrogen fixation.

scholarly journals Specific Host-Responsive Associations Between Medicago truncatula Accessions and Sinorhizobium Strains

2017 ◽  
Vol 30 (5) ◽  
pp. 399-409 ◽  
Author(s):  
Théophile Kazmierczak ◽  
Marianna Nagymihály ◽  
Florian Lamouche ◽  
Quentin Barrière ◽  
Ibtissem Guefrachi ◽  
...  
Keyword(s):  
Medicago Truncatula ◽  
Sinorhizobium Meliloti ◽  
Root Nodules ◽  
Nodule Formation ◽  
Bacterial Strains ◽  
Symbiotic Efficiency ◽  
Model Legume ◽  
Functional Studies ◽  
Multiple Parameters ◽  
Nitrogen Fixation Activity

Legume plants interact with rhizobia to form nitrogen-fixing root nodules. Legume-rhizobium interactions are specific and only compatible rhizobia and plant species will lead to nodule formation. Even within compatible interactions, the genotype of both the plant and the bacterial symbiont will impact on the efficiency of nodule functioning and nitrogen-fixation activity. The model legume Medicago truncatula forms nodules with several species of the Sinorhizobium genus. However, the efficiency of these bacterial strains is highly variable. In this study, we compared the symbiotic efficiency of Sinorhizobium meliloti strains Sm1021, 102F34, and FSM-MA, and Sinorhizobium medicae strain WSM419 on the two widely used M. truncatula accessions A17 and R108. The efficiency of the interactions was determined by multiple parameters. We found a high effectiveness of the FSM-MA strain with both M. truncatula accessions. In contrast, specific highly efficient interactions were obtained for the A17-WSM419 and R108-102F34 combinations. Remarkably, the widely used Sm1021 strain performed weakly on both hosts. We showed that Sm1021 efficiently induced nodule organogenesis but cannot fully activate the differentiation of the symbiotic nodule cells, explaining its weaker performance. These results will be informative for the selection of appropriate rhizobium strains in functional studies on symbiosis using these M. truncatula accessions, particularly for research focusing on late stages of the nodulation process.

scholarly journals Transcriptomic Analysis of Sinorhizobium meliloti and Medicago truncatula Symbiosis Using Nitrogen Fixation–Deficient Nodules

2015 ◽  
Vol 28 (8) ◽  
pp. 856-868 ◽  
Author(s):  
Claus Lang ◽  
Sharon R. Long
Keyword(s):  
Gene Expression ◽  
Nitrogen Fixation ◽  
Bacterial Infection ◽  
Medicago Truncatula ◽  
Sinorhizobium Meliloti ◽  
Cell Envelope ◽  
Root Nodules ◽  
Bacterial Cells ◽  
Nitrogen Fixing ◽  
Bacterial Genes

The bacterium Sinorhizobium meliloti interacts symbiotically with legume plant hosts such as Medicago truncatula to form nitrogen-fixing root nodules. During symbiosis, plant and bacterial cells differentiate in a coordinated manner, resulting in specialized plant cells that contain nitrogen-fixing bacteroids. Both plant and bacterial genes are required at each developmental stage of symbiosis. We analyzed gene expression in nodules formed by wild-type bacteria on six plant mutants with defects in nitrogen fixation. We observed differential expression of 482 S. meliloti genes with functions in cell envelope homeostasis, cell division, stress response, energy metabolism, and nitrogen fixation. We simultaneously analyzed gene expression in M. truncatula and observed differential regulation of host processes that may trigger bacteroid differentiation and control bacterial infection. Our analyses of developmentally arrested plant mutants indicate that plants use distinct means to control bacterial infection during early and late symbiotic stages.

scholarly journals Nicotianamine synthase 2 is required for symbiotic nitrogen fixation in Medicago truncatula nodules

2019 ◽  
Author(s):  
Viviana Escudero ◽  
Isidro Abreu ◽  
Eric del Sastre ◽  
Manuel Tejada-Jiménez ◽  
Camile Larue ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Medicago Truncatula ◽  
Symbiotic Nitrogen Fixation ◽  
Nitrogenase Activity ◽  
Root Nodules ◽  
Long Distance ◽  
Metal Transporters ◽  
Model Legume ◽  
Fluorescence Studies ◽  
Iron Delivery

SUMMARYSymbiotic nitrogen fixation carried out by the interaction between legumes and diazotrophic bacteria known as rhizobia requires of relatively large levels of transition metals. These elements act as cofactors of many key enzymes involved in this process. Metallic micronutrients are obtained from soil by the roots and directed to sink organs by the vasculature, in a process participated by a number of metal transporters and small organic molecules that mediate metal delivery in the plant fluids. Among the later, nicotianamine is one of the most important. Synthesized by nicotianamine synthases (NAS), this non-proteinogenic amino acid forms metal complexes participating in intracellular metal homeostasis and long-distance metal trafficking. Here we characterized the NAS2 gene from model legume Medicago truncatula. MtNAS2 is located in the root vasculature and in all nodule tissues in the infection and fixation zones. Symbiotic nitrogen fixation requires of MtNAS2 function, as indicated by the loss of nitrogenase activity in the insertional mutant nas2-1, a phenotype reverted by reintroduction of a wild-type copy of MtNAS2. This would be the result of the altered iron distribution in nas2-1 nodules, as indicated by X-ray fluorescence studies. Moreover, iron speciation is also affected in these nodules. These data suggest a role of nicotianamine in iron delivery for symbiotic nitrogen fixation.Significance StatementNicotianamine synthesis mediated by MtNAS2 is important for iron allocation for symbiotic nitrogen fixation by rhizobia in Medicago truncatula root nodules.

scholarly journals A toolbox for nodule development studies in chickpea: a hairy-root transformation protocol and an efficient laboratory strain of Mesorhizobium sp

2018 ◽  
Author(s):  
Drishti Mandal ◽  
Senjuti Sinharoy
Keyword(s):  
Nitrogen Fixation ◽  
Hairy Root ◽  
Root Nodules ◽  
Laboratory Strain ◽  
Nodule Development ◽  
Model Legume ◽  
Transformation Protocol ◽  
Evolutionary Diversification ◽  
Fluorescent Markers ◽  
Root Transformation

AbstractMesorhizobium sp. produces root nodules in chickpea. Chickpea and model legume Medicago truncatula are members of inverted repeat lacking clade (IRLC). The rhizobia after internalization inside plant cell called ‘bacteroid’. Nodule Specific Cysteine-rich (NCR) peptides in IRLC legumes guide bacteroids to a ‘terminally differentiated swollen (TDS)’ form. Bacteroids in chickpea are less TDS than those in Medicago. Nodule development in chickpea indicates recent evolutionary diversification and merits further study. A hairy root transformation protocol and an efficient laboratory strain are prerequisites for performing any genetic study on nodulation. We have standardized a protocol for composite plant generation in chickpea with a transformation frequency above 50%, as shown by fluorescent markers. This protocol also works well in different ecotypes of chickpea. Localization of subcellular markers in these transformed roots is similar to Medicago. When checked inside transformed nodules, peroxisomes were concentrated along the periphery of the nodules, while ER and golgi bodies surrounded the symbiosomes. Different Mesorhizobium strains were evaluated for their ability to initiate nodule development, and efficiency of nitrogen fixation. Inoculation with different strains resulted in different shapes of TDS bacteroids with variable nitrogen fixation. Our study provides a toolbox to study nodule development in the crop legume chickpea.

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