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 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 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 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 Nodule Organogenesis and Symbiotic Mutants of the Model Legume Lotus japonicus

1998 ◽  
Vol 11 (7) ◽  
pp. 684-697 ◽  
Author(s):  
Krzysztof Szczyglowski ◽  
Robert S. Shaw ◽  
Judith Wopereis ◽  
Sue Copeland ◽  
Dirk Hamburger ◽  
...  
Keyword(s):  
Root Development ◽  
Developmental Stages ◽  
Lotus Japonicus ◽  
Nuclear Gene ◽  
Common Mechanism ◽  
Nodule Formation ◽  
Wild Type ◽  
Ems Mutagenesis ◽  
Model Legume ◽  
Complementation Groups

A detailed microscopical analysis of the morphological features that distinguish different developmental stages of nodule organogenesis in wild-type Lotus japonicus ecotype Gifu B-129-S9 plants was performed, to provide the necessary framework for the evaluation of altered phenotypes of L. japonicus symbiotic mutants. Subsequently, chemical ethyl methanesulfonate (EMS) mutagenesis of L. japonicus was carried out. The analysis of approximately 3,000 M1 plants and their progeny yielded 20 stable L. japonicus symbiotic variants, consisting of at least 14 different symbiosis-associated loci or complementation groups. Moreover, a mutation affecting L. japonicus root development was identified that also conferred a hypernodulation response when a line carrying the corresponding allele (LjEMS102) was inoculated with rhizobia. The phenotype of the LjEMS102 line was characterized by the presence of nodule structures covering almost the entire root length (Nod++), and by a concomitant inhibition of both root and stem growth. A mutation in a single nuclear gene was shown to be responsible for both root and symbiotic phenotypes observed in the L. japonicus LjEMS102 line, suggesting that (a) common mechanism(s) regulating root development and nodule formation exists in legumes.

scholarly journals Spatiotemporal cytokinin signaling imaging reveals IPT3 function in nodule development in Medicago truncatula

2021 ◽  
Author(s):  
Paolo M. Triozzi ◽  
Thomas B. Irving ◽  
Henry W. Schmidt ◽  
Zachary P. Keyser ◽  
Sanhita Chakraborty ◽  
...  
Keyword(s):  
High Resolution ◽  
Medicago Truncatula ◽  
Sinorhizobium Meliloti ◽  
Root Nodules ◽  
Nodule Development ◽  
Nodule Formation ◽  
Symbiotic Association ◽  
Loss Of Function ◽  
Cytokinin Signaling ◽  
Tissue Specific

ABSTRACTMost legumes can establish a symbiotic association with soil rhizobia that triggers the development of root nodules. These nodules host the rhizobia and allow them to fix nitrogen efficiently. The perception of bacterial lipo-chitooligosaccharide (LCO) signal in the epidermis initiates a signaling cascade that allows rhizobial intracellular infection in the root and de-differentiation and activation of cell division that gives rise to the nodule. Nodule organogenesis and rhizobial infection need to be coupled in space and time for successful nodulation. The plant hormone cytokinin (CK) acts as an essential positive regulator of nodule organogenesis, and specific CK receptors are required for nodule formation. Temporal regulation of tissue-specific CK signaling and biosynthesis in response to LCOs or Sinorhizobium meliloti inoculation in Medicago truncatula remains poorly understood. In the present study, using a fluorescence-based CK sensor (TCSn::nls:tGFP), we performed a high-resolution tissue-specific temporal characterization of the CK response’s sequential activation during root infection and nodule development in M. truncatula after inoculation with S. meliloti. Loss-of-function mutants of the CK-biosynthetic gene ISOPENTENYL TRANSFERASE 3 (IPT3) showed impairment of nodulation, suggesting that IPT3 is required for nodule development in M. truncatula. Simultaneous live imaging of pIPT3::tdTOMATO and the CK sensor showed that IPT3 induction in the root stele at the base of nodule primordium contributes to CK biosynthesis, which in turn promotes expression of positive regulators of nodule organogenesis in M. truncatula.One-sentence summaryHigh-resolution spatiotemporal imaging of cytokinin signaling reveals IPT3 function during indeterminate nodule development in Medicago truncatula

scholarly journals Auxin Response Factor 2 (ARF2), ARF3, and ARF4 Mediate Both Lateral Root and Nitrogen Fixing Nodule Development in Medicago truncatula

2021 ◽  
Vol 12 ◽  
Author(s):  
Cristina Kirolinko ◽  
Karen Hobecker ◽  
Jiangqi Wen ◽  
Kirankumar S. Mysore ◽  
Andreas Niebel ◽  
...  
Keyword(s):  
Medicago Truncatula ◽  
Root Development ◽  
Lateral Root ◽  
Lateral Roots ◽  
Nodule Development ◽  
Nodule Formation ◽  
Mrna Levels ◽  
Nitrogen Fixing ◽  
Auxin Response ◽  
Small Interference Rna

Auxin Response Factors (ARFs) constitute a large family of transcription factors that mediate auxin-regulated developmental programs in plants. ARF2, ARF3, and ARF4 are post-transcriptionally regulated by the microRNA390 (miR390)/trans-acting small interference RNA 3 (TAS3) module through the action of TAS3-derived trans-acting small interfering RNAs (ta-siRNA). We have previously reported that constitutive activation of the miR390/TAS3 pathway promotes elongation of lateral roots but impairs nodule organogenesis and infection by rhizobia during the nitrogen-fixing symbiosis established between Medicago truncatula and its partner Sinorhizobium meliloti. However, the involvement of the targets of the miR390/TAS3 pathway, i.e., MtARF2, MtARF3, MtARF4a, and MtARF4b, in root development and establishment of the nitrogen-fixing symbiosis remained unexplored. Here, promoter:reporter fusions showed that expression of both MtARF3 and MtARF4a was associated with lateral root development; however, only the MtARF4a promoter was active in developing nodules. In addition, up-regulation of MtARF2, MtARF3, and MtARF4a/b in response to rhizobia depends on Nod Factor perception. We provide evidence that simultaneous knockdown of MtARF2, MtARF3, MtARF4a, and MtARF4b or mutation in MtARF4a impaired nodule formation, and reduced initiation and progression of infection events. Silencing of MtARF2, MtARF3, MtARF4a, and MtARF4b altered mRNA levels of the early nodulation gene nodulation signaling pathway 2 (MtNSP2). In addition, roots with reduced levels of MtARF2, MtARF3, MtARF4a, and MtARF4b, as well as arf4a mutant plants exhibited altered root architecture, causing a reduction in primary and lateral root length, but increasing lateral root density. Taken together, our results suggest that these ARF members are common key players of the morphogenetic programs that control root development and the formation of nitrogen-fixing nodules.

scholarly journals Expression of Medicago truncatula Genes Responsive to Nitric Oxide in Pathogenic and Symbiotic Conditions

2008 ◽  
Vol 21 (6) ◽  
pp. 781-790 ◽  
Author(s):  
Alberto Ferrarini ◽  
Matteo De Stefano ◽  
Emmanuel Baudouin ◽  
Chiara Pucciariello ◽  
Annalisa Polverari ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Medicago Truncatula ◽  
Regulatory Networks ◽  
Sinorhizobium Meliloti ◽  
Biotic Interactions ◽  
Hypersensitive Reaction ◽  
Nodule Formation ◽  
Polymorphism Analysis ◽  
Symbiotic Interaction ◽  
Physiological Relevance

Nitric oxide (NO) is involved in diverse physiological processes in plants, including growth, development, response to pathogens, and interactions with beneficial microorganisms. In this work, a dedicated microarray representing the widest database available of NO-related transcripts in plants has been produced with 999 genes identified by a cDNA amplified fragment length polymorphism analysis as modulated in Medicago truncatula roots treated with two NO donors. The microarray then was used to monitor the expression of NO-responsive genes in M. truncatula during the incompatible interaction with the foliar pathogen Colletotrichum trifolii race 1 and during the symbiotic interaction with Sinorhizobium meliloti 1021. A wide modulation of NO-related genes has been detected during the hypersensitive reaction or during nodule formation and is discussed with special emphasis on the physiological relevance of these genes in the context of the two biotic interactions. This work clearly shows that NO-responsive genes behave differently depending on the plant organ and on the type of interaction, strengthening the need to consider regulatory networks, including different signaling molecules.

scholarly journals Structure and antimicrobial activity of NCR169, a nodule-specific cysteine-rich peptide of Medicago truncatula

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Noriyoshi Isozumi ◽  
Yuya Masubuchi ◽  
Tomohiro Imamura ◽  
Masashi Mori ◽  
Hironori Koga ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Medicago Truncatula ◽  
Mechanism Of Action ◽  
Disulfide Bonds ◽  
Sinorhizobium Meliloti ◽  
Bound State ◽  
Disulfide Linkage ◽  
Model Legume ◽  
Nmr Structures ◽  
And Function

AbstractA model legume, Medicago truncatula, has over 600 nodule-specific cysteine-rich (NCR) peptides required for symbiosis with rhizobia. Among them, NCR169, an essential factor for establishing symbiosis, has four cysteine residues that are indispensable for its function. However, knowledge of NCR169 structure and mechanism of action is still lacking. In this study, we solved two NMR structures of NCR169 caused by different disulfide linkage patterns. We show that both structures have a consensus C-terminal β-sheet attached to an extended N-terminal region with dissimilar features; one moves widely, whereas the other is relatively stapled. We further revealed that the disulfide bonds of NCR169 contribute to its structural stability and solubility. Regarding the function, one of the NCR169 oxidized forms could bind to negatively charged bacterial phospholipids. Furthermore, the positively charged lysine-rich region of NCR169 may be responsible for its antimicrobial activity against Escherichia coli and Sinorhizobium meliloti. This active region was disordered even in the phospholipid bound state, suggesting that the disordered conformation of this region is key to its function. Morphological observations suggested the mechanism of action of NCR169 on bacteria. The present study on NCR169 provides new insights into the structure and function of NCR peptides.

scholarly journals Comparison of nodule endophyte composition, diversity, and gene content between Medicago truncatula genotypes

2021 ◽  
Author(s):  
Mannix Burns ◽  
Brendan Epstein ◽  
Liana Burghardt
Keyword(s):  
Functional Groups ◽  
Medicago Truncatula ◽  
Root Nodules ◽  
Bacterial Endophytes ◽  
Host Genotype ◽  
Model Legume ◽  
Symbiotic Relationships ◽  
Functional Assays ◽  
Altered Gene ◽  
Significant Direct Effect

Leguminous plants form symbiotic relationships with rhizobia. These nitrogen-fixing bacteria live in specialized root organs called nodules. While rhizobia form the most notable host relationship within root nodules, other bacterial endophytes also inhabit these root nodules and can influence host-rhizobia interactions as well as exert effects of their own, whether beneficial or detrimental. In this study, we investigate differences in nodule communities between genotypes (A17 and R108) of a single plant species, the model legume Medicago truncatula. While diversity of endophytes in nodules was similar across hosts, both nodule endophyte composition and gene functional groups differed. In contrast to the significant direct effect of host genotype, neither the presence nor identity of a host in the previous generation (either A17 or R108) had a significant effect on the nodule endophyte diversity or composition. However, whether or not a host was present altered gene functional groups. We conclude that genetic variation within a legume host species can play an important role in the establishment of nodule microbiomes. Further studies, including GWAS and functional assays, can open the door for engineering and optimizing nodule endophyte communities that promote growth or have other beneficial qualities.

Sign in / Sign up

Export Citation Format

Share Document