scholarly journals Medicago truncatula Yellow Stripe-Like7 encodes a peptide transporter required for symbiotic nitrogen fixation

2020 ◽  
Author(s):  
Rosario Castro-Rodríguez ◽  
María Reguera ◽  
Viviana Escudero ◽  
Patricia Gil-Díez ◽  
Julia Quintana ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Transition Metal ◽  
Medicago Truncatula ◽  
Symbiotic Nitrogen Fixation ◽  
Root Nodules ◽  
Metal Homeostasis ◽  
Peptide Transporter ◽  
Short Peptides ◽  
Yellow Stripe ◽  
Mutant Lines

ABSTRACTYellow Stripe-Like (YSL) proteins are a family of plant transporters typically involved in transition metal homeostasis. The substrate of three of the four YSL clades (clades I, II, and IV) are metal complexes with non-proteinogenic amino acid nicotianamine or its derivatives. No such transport capabilities have been shown for any member of the remaining clade (clade III), which is able to translocate short peptides across the membranes instead. The connection between clade III YSL members and metal homeostasis might have been masked by the functional redundancy characteristic of this family. This might have been circumvented in legumes through neofunctionalization of YSLs to ensure a steady supply of transition metals for symbiotic nitrogen fixation in root nodules. To test this possibility, Medicago truncatula clade III transporter MtYSL7 has been studied both when the plant was fertilized with ammonium nitrate or when nitrogen had to be provided by endosymbiotic rhizobia within the root nodules. MtYSL7 is a plasma membrane protein expressed in the vasculature and in the nodule cortex. This protein is able to transport short peptides into the cytosol, although none with known metal homeostasis roles. Reducing MtYSL7 expression levels resulted in diminished nitrogen fixation rates. In addition, nodules of mutant lines lacking YSL7 accumulated more copper and iron, the later the likely result of increased expression in roots of iron uptake and delivery genes. The available data is indicative of a role of MtYSL7, and likely other clade III YSLs, in transition metal homeostasis.ONE SENTENCE SUMMARYMedicago truncatula YSL7 is a peptide transporter required for symbiotic nitrogen fixation in legume nodules, likely controlling transition metal allocation to these organs.

Medicago truncatula Yellow Stripe‐Like7 encodes a peptide transporter participating in symbiotic nitrogen fixation

2021 ◽  
Author(s):  
Rosario Castro‐Rodríguez ◽  
Viviana Escudero ◽  
María Reguera ◽  
Patricia Gil‐Díez ◽  
Julia Quintana ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Medicago Truncatula ◽  
Symbiotic Nitrogen Fixation ◽  
Peptide Transporter ◽  
Yellow Stripe

scholarly journals Loss of the nodule-specific cysteine rich peptide, NCR169, abolishes symbiotic nitrogen fixation in the Medicago truncatula dnf7 mutant

2015 ◽  
Vol 112 (49) ◽  
pp. 15232-15237 ◽  
Author(s):  
Beatrix Horváth ◽  
Ágota Domonkos ◽  
Attila Kereszt ◽  
Attila Szűcs ◽  
Edit Ábrahám ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Medicago Truncatula ◽  
Symbiotic Nitrogen Fixation ◽  
Root Nodules ◽  
Nitrogen Fixing ◽  
In Planta ◽  
Functional Roles ◽  
Absolute Requirement ◽  
Cell Layers

Host compatible rhizobia induce the formation of legume root nodules, symbiotic organs within which intracellular bacteria are present in plant-derived membrane compartments termed symbiosomes. In Medicago truncatula nodules, the Sinorhizobium microsymbionts undergo an irreversible differentiation process leading to the development of elongated polyploid noncultivable nitrogen fixing bacteroids that convert atmospheric dinitrogen into ammonia. This terminal differentiation is directed by the host plant and involves hundreds of nodule specific cysteine-rich peptides (NCRs). Except for certain in vitro activities of cationic peptides, the functional roles of individual NCR peptides in planta are not known. In this study, we demonstrate that the inability of M. truncatula dnf7 mutants to fix nitrogen is due to inactivation of a single NCR peptide, NCR169. In the absence of NCR169, bacterial differentiation was impaired and was associated with early senescence of the symbiotic cells. Introduction of the NCR169 gene into the dnf7-2/NCR169 deletion mutant restored symbiotic nitrogen fixation. Replacement of any of the cysteine residues in the NCR169 peptide with serine rendered it incapable of complementation, demonstrating an absolute requirement for all cysteines in planta. NCR169 was induced in the cell layers in which bacteroid elongation was most pronounced, and high expression persisted throughout the nitrogen-fixing nodule zone. Our results provide evidence for an essential role of NCR169 in the differentiation and persistence of nitrogen fixing bacteroids in M. truncatula.

scholarly journals Structural Modeling and in planta Complementation Studies Link Mutated Residues of the Medicago truncatula Nitrate Transporter NPF1.7 to Functionality in Root Nodules

2021 ◽  
Vol 12 ◽  
Author(s):  
Yao-Chuan Yu ◽  
Rebecca Dickstein ◽  
Antonella Longo
Keyword(s):  
Nitrogen Fixation ◽  
Medicago Truncatula ◽  
Conformational Changes ◽  
Root Nodules ◽  
Salt Bridge ◽  
Peptide Transporter ◽  
Nitrate Transport ◽  
In Planta ◽  
Transporter Family ◽  
Major Facilitator

Symbiotic nitrogen fixation is a complex and regulated process that takes place in root nodules of legumes and allows legumes to grow in soils that lack nitrogen. Nitrogen is mostly acquired from the soil as nitrate and its level in the soil affects nodulation and nitrogen fixation. The mechanism(s) by which legumes modulate nitrate uptake to regulate nodule symbiosis remain unclear. In Medicago truncatula, the MtNPF1.7 transporter has been shown to control nodulation, symbiosis, and root architecture. MtNPF1.7 belongs to the nitrate/peptide transporter family and is a symporter with nitrate transport driven by proton(s). In this study we combined in silico structural predictions with in planta complementation of the severely defective mtnip-1 mutant plants to understand the role of a series of distinct amino acids in the transporter’s function. Our results support hypotheses about the functional importance of the ExxE(R/K) motif including an essential role for the first glutamic acid of the motif in proton(s) and possibly substrate transport. Results reveal that Motif A, a motif conserved among major facilitator transport (MFS) proteins, is essential for function. We hypothesize that it participates in intradomain packing of transmembrane helices and stabilizing one conformation during transport. Our results also question the existence of a putative TMH4-TMH10 salt bridge. These results are discussed in the context of potential nutrient transport functions for MtNPF1.7. Our findings add to the knowledge of the mechanism of alternative conformational changes as well as symport transport in NPFs and enhance our knowledge of the mechanisms for nitrate signaling.

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 The Medicago truncatula Yellow Stripe1-Like3 gene is involved in vascular delivery of transition metals to root nodules

2020 ◽  
Vol 71 (22) ◽  
pp. 7257-7269
Author(s):  
Rosario Castro-Rodríguez ◽  
Isidro Abreu ◽  
María Reguera ◽  
Lorena Novoa-Aponte ◽  
Ana Mijovilovich ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Transition Metals ◽  
Medicago Truncatula ◽  
Symbiotic Nitrogen Fixation ◽  
Root Nodules ◽  
Apical Region ◽  
Long Distance ◽  
Metal Transporters ◽  
Model Legume ◽  
Iron And Zinc

Abstract Symbiotic nitrogen fixation carried out in legume root nodules requires transition metals. These nutrients are delivered by the host plant to the endosymbiotic nitrogen-fixing bacteria living within the nodule cells, a process in which vascular transport is essential. As members of the Yellow Stripe-Like (YSL) family of metal transporters are involved in root to shoot transport, they should also be required for root to nodule metal delivery. The genome of the model legume Medicago truncatula encodes eight YSL proteins, four of them with a high degree of similarity to Arabidopsis thaliana YSLs involved in long-distance metal trafficking. Among them, MtYSL3 is a plasma membrane protein expressed by vascular cells in roots and nodules and by cortical nodule cells. Reducing the expression level of this gene had no major effect on plant physiology when assimilable nitrogen was provided in the nutrient solution. However, nodule functioning was severely impaired, with a significant reduction of nitrogen fixation capabilities. Further, iron and zinc accumulation and distribution changed. Iron was retained in the apical region of the nodule, while zinc became strongly accumulated in the nodule veins in the ysl3 mutant. These data suggest a role for MtYSL3 in vascular delivery of iron and zinc to symbiotic nitrogen fixation.

scholarly journals Medicago truncatula Yellow Stripe1-Like3 gene is involved in symbiotic nitrogen fixation

2019 ◽  
Author(s):  
Rosario Castro-Rodríguez ◽  
Isidro Abreu ◽  
María Reguera ◽  
Lorena Novoa-Aponte ◽  
Ana Mijovilovich ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Medicago Truncatula ◽  
Symbiotic Nitrogen Fixation ◽  
Root Nodules ◽  
Major Effect ◽  
Apical Region ◽  
Long Distance ◽  
Metal Transporters ◽  
Model Legume ◽  
Iron And Zinc

AbstractSymbiotic nitrogen fixation carried out in legume root nodules requires transition metals. These nutrients are delivered by the host plant to the endosymbiotic nitrogen-fixing bacteria living with the nodule cells, a process in which vascular transport is essential. As occurs in root-to-shoot transport, members of the Yellow Stripe-Like (YSL) family of metal transporters should also be required for root-to-nodule metal delivery. The genome of the model legume Medicago truncatula encodes for eight YSL proteins, four of them with a high degree of similarity to Arabidopsis thaliana YSLs involved in long-distance metal trafficking. Among them, MtYSL3 is a plasma membrane protein expressed by vascular cells in roots and nodules, and by cortical nodule cells. Reducing expression levels of this gene had no major effect on plant physiology when assimilable nitrogen was provided in the nutrient solution. However, nodule functioning was severely impaired, with a significant reduction of nitrogen fixation capabilities. Further, iron and zinc accumulation and distribution changed. Iron was retained in the apical region of the nodule, while zinc became strongly accumulated in the nodule veins in the ysl3 mutant. These data suggest a role of MtYSL3 in vascular delivery of iron and zinc to symbiotic nitrogen fixation.HighlightMedicago truncatula YSL3 transporter is required for optimal nitrogen fixation in root nodules, mediating iron and zinc distribution in these organs.

Phoma medicaginis colonizes Medicago truncatula root nodules and affects nitrogen fixation capacity

2014 ◽  
Vol 141 (2) ◽  
pp. 375-383 ◽  
Author(s):  
Saif-Allah Chihaoui ◽  
Naceur Djébali ◽  
Moncef Mrabet ◽  
Fathi Barhoumi ◽  
Ridha Mhamdi ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Medicago Truncatula ◽  
Root Nodules ◽  
Phoma Medicaginis ◽  
Fixation Capacity

scholarly journals Nicotianamine Synthase 2 Is Required for Symbiotic Nitrogen Fixation in Medicago truncatula Nodules

2020 ◽  
Vol 10 ◽  
Author(s):  
Viviana Escudero ◽  
Isidro Abreu ◽  
Eric del Sastre ◽  
Manuel Tejada-Jiménez ◽  
Camille Larue ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Medicago Truncatula ◽  
Symbiotic Nitrogen Fixation ◽  
Nicotianamine Synthase

scholarly journals The rhizobial autotransporter determines the symbiotic nitrogen fixation activity of Lotus japonicus in a host-specific manner

2020 ◽  
Vol 117 (3) ◽  
pp. 1806-1815 ◽  
Author(s):  
Yoshikazu Shimoda ◽  
Yuki Nishigaya ◽  
Hiroko Yamaya-Ito ◽  
Noritoshi Inagaki ◽  
Yosuke Umehara ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Host Plant ◽  
Symbiotic Nitrogen Fixation ◽  
Root Nodules ◽  
Lotus Japonicus ◽  
Dependent Manner ◽  
Strain Specificity ◽  
Passenger Domain ◽  
Aspartic Peptidase ◽  
Specific Manner

Leguminous plants establish endosymbiotic associations with rhizobia and form root nodules in which the rhizobia fix atmospheric nitrogen. The host plant and intracellular rhizobia strictly control this symbiotic nitrogen fixation. We recently reported a Lotus japonicus Fix− mutant, apn1 (aspartic peptidase nodule-induced 1), that impairs symbiotic nitrogen fixation. APN1 encodes a nodule-specific aspartic peptidase involved in the Fix− phenotype in a rhizobial strain-specific manner. This host-strain specificity implies that some molecular interactions between host plant APN1 and rhizobial factors are required, although the biological function of APN1 in nodules and the mechanisms governing the interactions are unknown. To clarify how rhizobial factors are involved in strain-specific nitrogen fixation, we explored transposon mutants of Mesorhizobium loti strain TONO, which normally form Fix− nodules on apn1 roots, and identified TONO mutants that formed Fix+ nodules on apn1. The identified causal gene encodes an autotransporter, part of a protein secretion system of Gram-negative bacteria. Expression of the autotransporter gene in M. loti strain MAFF3030399, which normally forms Fix+ nodules on apn1 roots, resulted in Fix− nodules. The autotransporter of TONO functions to secrete a part of its own protein (a passenger domain) into extracellular spaces, and the recombinant APN1 protein cleaved the passenger protein in vitro. The M. loti autotransporter showed the activity to induce the genes involved in nodule senescence in a dose-dependent manner. Therefore, we conclude that the nodule-specific aspartic peptidase, APN1, suppresses negative effects of the rhizobial autotransporter in order to maintain effective symbiotic nitrogen fixation in root nodules.

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