scholarly journals Transcriptomic Changes in Medicago truncatula and Lotus japonicus Root Nodules during Drought Stress

2019 ◽  
Vol 20 (5) ◽  
pp. 1204 ◽  
Author(s):  
Izabela Sańko-Sawczenko ◽  
Barbara Łotocka ◽  
Jakub Mielecki ◽  
Hanna Rekosz-Burlaga ◽  
Weronika Czarnocka
Keyword(s):  
Gene Expression ◽  
Medicago Truncatula ◽  
Sinorhizobium Meliloti ◽  
Nitrogenase Activity ◽  
Root Nodules ◽  
Lotus Japonicus ◽  
Global Gene Expression ◽  
Water Shortage ◽  
Mesorhizobium Loti ◽  
Yield Production

Drought is one of the major environmental factors limiting biomass and seed yield production in agriculture. In this research, we focused on plants from the Fabaceae family, which has a unique ability for the establishment of symbiosis with nitrogen-fixing bacteria, and are relatively susceptible to water limitation. We have presented the changes in nitrogenase activity and global gene expression occurring in Medicago truncatula and Lotus japonicus root nodules during water deficit. Our results proved a decrease in the efficiency of nitrogen fixation, as well as extensive changes in plant and bacterial transcriptomes, shortly after watering cessation. We showed for the first time that not only symbiotic plant components but also Sinorhizobium meliloti and Mesorhizobium loti bacteria residing in the root nodules of M. truncatula and L. japonicus, respectively, adjust their gene expression in response to water shortage. Although our results demonstrated that both M. truncatula and L. japonicus root nodules were susceptible to water deprivation, they indicated significant differences in plant and bacterial response to drought between the tested species, which might be related to the various types of root nodules formed by these species.

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 Salt stress enhances early symbiotic gene expression in Medicago truncatula and induces a stress-specific set of rhizobium-responsive genes.

2021 ◽  
Author(s):  
Sanhita Chakraborty ◽  
Heather Driscoll ◽  
Juan Abrahante Lloréns ◽  
Fan Zhang ◽  
Robert Fisher ◽  
...  
Keyword(s):  
Gene Expression ◽  
Salt Stress ◽  
Medicago Truncatula ◽  
Sinorhizobium Meliloti ◽  
Root Nodules ◽  
Symbiotic Association ◽  
Symbiotic Gene ◽  
Nod Factor ◽  
Early Nodulin ◽  
Regulated Gene Expression

Salt stress is a major agricultural concern inhibiting not only plant growth but also the symbiotic association between legume roots and the soil bacteria rhizobia. This symbiotic association is initiated by a molecular dialogue between the two partners, leading to the activation of a signaling cascade in the legume host and ultimately the formation of nitrogen-fixing root nodules. Here we show that a moderate salt stress increases the responsiveness of early symbiotic genes in Medicago truncatula to its symbiotic partner, Sinorhizobium meliloti, while conversely, inoculation with S. meliloti counteracts salt-regulated gene expression, restoring one-third to control levels. Our analysis of Early Nodulin 11 shows that salt-induced expression is dynamic, Nod-factor dependent, and requires the ionic, but not the osmotic, component of salt. We demonstrate that salt stimulation of rhizobium-induced gene expression requires NSP2, which functions as a node to integrate the abiotic and biotic signals. In addition, our work reveals that inoculation with Sinorhizobium meliloti succinoglycan mutants also hyperinduces ENOD11 expression in the presence or absence of salt, suggesting a possible link between rhizobial exopolysaccharide and the plant response to salt stress. Finally, we identify an accessory set of genes that are induced by rhizobium only under conditions of salt stress and have not been previously identified as being nodulation-related genes. Our data suggests that interplay of core nodulation genes with different accessory sets, specific for different abiotic conditions, function to establish the symbiosis. Together, our findings reveal a complex and dynamic interaction between plant, microbe, and environment.

Gene Expression of Medicago sativa Inoculated with Sinorhizobium meliloti as Modulated by the Xenobiotics Cadmium and Fluoranthene

2000 ◽  
Vol 55 (3-4) ◽  
pp. 222-232 ◽  
Author(s):  
Heike Neumann ◽  
Dietrich Werner
Keyword(s):  
Gene Expression ◽  
Arabidopsis Thaliana ◽  
Medicago Sativa ◽  
Sinorhizobium Meliloti ◽  
Rhizobium Meliloti ◽  
Root Nodules ◽  
Cadmium Concentration ◽  
Transcript Level ◽  
Northern Hybridization ◽  
Fresh Weight

Abstract Alfalfa plants (Medicago sativa cv. Europe) inoculated with Sinorhizobium meliloti 2011 (formerly Rhizobium meliloti, de Lajudie et al., 1994) were cultivated for 14 days under standardized growth conditions in mineral medium with addition of the heavy metal cadmium or the polycyclic aromatic hydrocarbon fluoranthene. These xenobiotics significantly reduced the numbers of root nodules before any visible damage to the plant could be detected. EC10. EC50, and EC90 (effective concentrations reducing nodulation, shoot and root fresh weight by 10, 50, or 90% compared to the control without pollutant) were calculated. EC50 for cadmium ranged from 5.8 jam (nodulation) to more than 20 μᴍ (root fresh weight). Testing fluoranthene resulted in an EC50 of 2.5 μg cm-2 for nodulation, and EC50 values of more than 35 μg cm-2 for shoot and root biomass production, indicating that the effect parameter nodulation is 10-fold more sensitive than shoot and root fresh weight. With m RNA differential display techniques the effects of both xenobiotics on gene expression in alfalfa root systems were studied. 37 differentially displayed transcripts were detected. Two of them, called DDMs1 and DDMs2, were confirmed by northern hybridization to be down-regulated in the presence of the xenobiotics. The expression of transcript DDMs1 was enhanced in alfalfa control plants inoculated with rhizobia, the transcript level was increased 2.5-3-fold compared to non-inoculated plants. This positive effect of nodulation was suppressed, partly by 35 μg cm-2 fluoranthene and totally by 20 μᴍ cadmium. The decrease in DDMsl transcription was highly affected by the cadmium concentration with an EC50 of 5.9 μᴍ . Compared to nodulation, almost identical EC10, EC50. and EC90 values were found for DDMsl expression. Sequence analysis of DDMsl revealed a significant overall homology (50% identity) to a hypothetical protein from Arabidopsis thaliana with high similarity to a copper transporting ATPase. High levels of transcript DDMs2 were observed in control plants with a 50% decrease in the xenobiotic-treated plants. DDM s2 gave a strong homology (82% identity) to the cytoplasmatic 60S ribosomal protein L18 from Arabidopsis thaliana.

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 Defects in Rhizobial Cyclic Glucan and Lipopolysaccharide Synthesis Alter Legume Gene Expression During Nodule Development

2008 ◽  
Vol 21 (1) ◽  
pp. 50-60 ◽  
Author(s):  
Alejandra L. D'Antuono ◽  
Thomas Ott ◽  
Lene Krusell ◽  
Vera Voroshilova ◽  
Rodolfo A. Ugalde ◽  
...  
Keyword(s):  
Gene Expression ◽  
Mutant Strain ◽  
Early Recognition ◽  
Lotus Japonicus ◽  
Cdna Array ◽  
Nodule Development ◽  
Marker Genes ◽  
Wild Type ◽  
Mesorhizobium Loti ◽  
Expression Of Genes

cDNA array technology was used to compare transcriptome profiles of Lotus japonicus roots inoculated with a Mesorhizobium loti wild-type and two mutant strains affected in cyclic β(1-2) glucan synthesis (cgs) and in lipopolysaccharide synthesis (lpsβ2). Expression of genes associated with the development of a fully functional nodule was significantly affected in plants inoculated with the cgs mutant. Array results also revealed that induction of marker genes for nodule development was delayed when plants were inoculated with the lpsβ2 mutant. Quantitative real-time reverse-transcriptase polymerase chain reaction was used to quantify gene expression of a subset of genes involved in plant defense response, redox metabolism, or genes that encode for nodulins. The majority of the genes analyzed in this study were more highly expressed in roots inoculated with the wild type compared with those inoculated with the cgs mutant strain. Some of the genes exhibited a transient increase in transcript levels during intermediate steps of normal nodule development while others displayed induced expression during the final steps of nodule development. Ineffective nodules induced by the glucan mutant showed higher expression of phenylalanine ammonia lyase than wild-type nodules. Differences in expression pattern of genes involved in early recognition and signaling were observed in plants inoculated with the M. loti mutant strain affected in the synthesis of cyclic glucan.

scholarly journals Differential Effects of Combined N Sources on Early Steps of the Nod Factor–Dependent Transduction Pathway in Lotus japonicus

2007 ◽  
Vol 20 (8) ◽  
pp. 994-1003 ◽  
Author(s):  
Ani Barbulova ◽  
Alessandra Rogato ◽  
Enrica D'Apuzzo ◽  
Selim Omrane ◽  
Maurizio Chiurazzi
Keyword(s):  
Root Nodules ◽  
Lotus Japonicus ◽  
Small Scale ◽  
Nodule Formation ◽  
Inhibitory Effects ◽  
Nod Factor ◽  
Mesorhizobium Loti ◽  
N Sources ◽  
N Starvation ◽  
And Function

The development of nitrogen-fixing nodules in legumes is induced by perception of lipochitin-oligosaccharide signals secreted by a bacterial symbiont. Nitrogen (N) starvation is a prerequisite for the formation, development, and function of root nodules, and high levels of combined N in the form of nitrate or ammonium can completely abolish nodule formation. We distinguished between nitrate and ammonium inhibitory effects by identifying when and where these combined N sources interfere with the Nod-factor-induced pathway. Furthermore, we present a small-scale analysis of the expression profile, under different N conditions, of recently identified genes involved in the Nod-factor-induced pathway. In the presence of high levels of nitrate or ammonium, the NIN gene fails to be induced 24 h after the addition of Nod factor compared with plants grown under N-free conditions. This induction is restored in the hypernodulating nitrate-tolerant har1-3 mutant only in the presence of 10 and 20 mM KNO3. These results were confirmed in Lotus plants inoculated with Mesorhizobium loti. NIN plays a key role in the nodule organogenesis program and its downregulation may represent a crucial event in the nitrate-dependent pathway leading to the inhibition of nodule organogenesis.

scholarly journals Absence of Symbiotic Leghemoglobins Alters Bacteroid and Plant Cell Differentiation During Development of Lotus japonicus Root Nodules

2009 ◽  
Vol 22 (7) ◽  
pp. 800-808 ◽  
Author(s):  
Thomas Ott ◽  
John Sullivan ◽  
Euan K. James ◽  
Emmanouil Flemetakis ◽  
Catrin Günther ◽  
...  
Keyword(s):  
Gene Expression ◽  
Nitrogen Fixation ◽  
Cell Differentiation ◽  
Root Nodules ◽  
Lotus Japonicus ◽  
Nodule Development ◽  
Primary And Secondary Metabolism ◽  
Bacterial Differentiation ◽  
Plant Genes ◽  
Bacterial Genes

During development of legume root nodules, rhizobia and their host plant cells undergo profound differentiation, which is underpinned by massive changes in gene expression in both symbiotic partners. Oxygen concentrations in infected and surrounding uninfected cells drop precipitously during nodule development. To assess what effects this has on plant and bacterial cell differentiation and gene expression, we used a leghemoglobin-RNA-interference (LbRNAi) line of Lotus japonicus, which is devoid of leghemoglobins and has elevated levels of free-oxygen in its nodules. Bacteroids in LbRNAi nodules showed altered ultrastructure indicating changes in bacterial differentiation. Transcript analysis of 189 plant and 192 bacterial genes uncovered many genes in both the plant and bacteria that were differentially regulated during nodulation of LbRNAi plants compared with the wild type (containing Lb and able to fix nitrogen). These included fix and nif genes of the bacteria, which are involved in microaerobic respiration and nitrogen fixation, respectively, and plant genes involved in primary and secondary metabolism. Metabolite analysis revealed decreased levels of many amino acids in nodules of LbRNAi plants, consistent with the defect in symbiotic nitrogen fixation of this line.

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 The Sinorhizobium meliloti SyrM Regulon: Effects on Global Gene Expression Are Mediated bysyrAandnodD3

2015 ◽  
Vol 197 (10) ◽  
pp. 1792-1806 ◽  
Author(s):  
Melanie J. Barnett ◽  
Sharon R. Long
Keyword(s):  
Gene Expression ◽  
Sinorhizobium Meliloti ◽  
Developmental Process ◽  
Global Gene Expression ◽  
Subsequent Increase ◽  
Altered Expression ◽  
Content Type ◽  
Regulatory Circuit ◽  
Regulatory Circuits ◽  
Exogenous Compounds

ABSTRACTInSinorhizobium meliloti, three NodD transcriptional regulators activate bacterial nodulation (nod) gene expression. NodD1 and NodD2 require plant compounds to activatenodgenes. The NodD3 protein does not require exogenous compounds to activatenodgene expression; instead, another transcriptional regulator, SyrM, activatesnodD3expression. In addition, NodD3 can activatesyrMexpression. SyrM also activates expression of another gene,syrA, which when overexpressed causes a dramatic increase in exopolysaccharide production. In a previous study, we identified more than 200 genes with altered expression in a strain overexpressingnodD3. In this work, we define the transcriptomes of strains overexpressingsyrMorsyrA. ThesyrM,nodD3, andsyrAoverexpression transcriptomes share similar gene expression changes; analyses imply thatnodD3andsyrAare the only targets directly activated by SyrM. We propose that most of the gene expression changes observed whennodD3is overexpressed are due to NodD3 activation ofsyrMexpression, which in turn stimulates SyrM activation ofsyrAexpression. The subsequent increase in SyrA abundance results in broad changes in gene expression, most likely mediated by the ChvI-ExoS-ExoR regulatory circuit.IMPORTANCESymbioses with bacteria are prevalent across the animal and plant kingdoms. Our system of study, the rhizobium-legume symbiosis (Sinorhizobium melilotiandMedicagospp.), involves specific host-microbe signaling, differentiation in both partners, and metabolic exchange of bacterial fixed nitrogen for host photosynthate. During this complex developmental process, both bacteria and plants undergo profound changes in gene expression. TheS. melilotiSyrM-NodD3-SyrA and ChvI-ExoS-ExoR regulatory circuits affect gene expression and are important for optimal symbiosis. In this study, we defined the transcriptomes ofS. melilotioverexpressing SyrM or SyrA. In addition to identifying new targets of the SyrM-NodD3-SyrA regulatory circuit, our work further suggests how it is linked to the ChvI-ExoS-ExoR regulatory circuit.

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