Characterization of an effective actinorhizal microsymbiont, Frankia sp. AvcI1 (Actinomycetales)

1980 ◽  
Vol 26 (9) ◽  
pp. 1066-1071 ◽  
Author(s):  
Dwight Baker ◽  
John G. Torrey
Keyword(s):  
Host Range ◽  
Root Nodules ◽  
Axenic Culture ◽  
Growth Characteristics ◽  
Nitrogen Fixing ◽  
Alnus Viridis ◽  
Distinctive Morphology

The actinomycete, Frankia sp. AvcI1, isolated from root nodules of Alnus viridis ssp. crispa was grown in axenic culture and used to inoculate host seedlings. This bacterium has been shown to be an infective and effective nitrogen-fixing microsymbiont which can be distinguished from other frankiae, in vitro, on the basis of size, distinctive morphology, and growth characteristics. Cross-inoculation studies indicated that the host range of this symbiont encompasses all of the members of the genera Alnus, Myrica, and Comptonia tested. In all cases, the symbioses developed were effective in fixing atmospheric dinitrogen.

Characterization of an ineffective actinorhizal microsymbiont, Frankia sp. EuI1 (Actinomycetales)

1980 ◽  
Vol 26 (9) ◽  
pp. 1072-1089 ◽  
Author(s):  
Dwight Baker ◽  
William Newcomb ◽  
John G. Torrey
Keyword(s):  
Host Range ◽  
Nitrogenase Activity ◽  
Root Nodules ◽  
Host Cells ◽  
Vesicle Formation ◽  
Nitrogen Fixing ◽  
Elaeagnus Umbellata

The actinomycete, Frankia sp. EuI1, isolated from root nodules of Elaeagnus umbellata is an infective endophyte but which lacks the ability to form an effective nitrogen-fixing symbiosis with its host. This ineffective organism can be distinguished easily from other frankiae, in vitro, on the basis of size, morphology, and the elaboration of a diffusible pigment. Cross-inoculation studies indicated that the host range of this symbiont is narrow and probably restricted to the Elaeagnaceae. In all cases of nodulation the symbiosis never developed nitrogenase activity and the microsymbiont never produced endophytic vesicles within the infected host cells. Sporangia were produced in vivo and in vitro so the morphogenetic block is apparently restricted to vesicle formation.

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 Purification and partial characterization of a pyruvate oxidoreductase from the photosynthetic bacterium Rhodospirillum rubrum grown under nitrogen-fixing conditions

1991 ◽  
Vol 279 (1) ◽  
pp. 155-158 ◽  
Author(s):  
E Brostedt ◽  
S Nordlund
Keyword(s):  
Klebsiella Pneumoniae ◽  
Rhodospirillum Rubrum ◽  
Nitrogenase Activity ◽  
Photosynthetic Bacterium ◽  
Molecular Properties ◽  
Partial Characterization ◽  
Nitrogen Fixing ◽  
Pyruvate Oxidoreductase

A pyruvate oxidoreductase with the capacity to support pyruvate-dependent nitrogenase activity in vitro has been purified from the photosynthetic bacterium Rhodospirillum rubrum. The enzyme requires CoA for activity and is irreversibly inactivated by oxygen. The molecular properties and Km values for the substrates have been studied. In supporting nitrogenase activity addition of ferredoxin is required. Overall the enzyme is similar to the nif-specific pyruvate: flavodoxin oxidoreductase purified from Klebsiella pneumoniae.

scholarly journals Consequences of in vitro host shift for St. Louis encephalitis virus

2014 ◽  
Vol 95 (6) ◽  
pp. 1281-1288 ◽  
Author(s):  
Alexander T. Ciota ◽  
Anne F. Payne ◽  
Kiet A. Ngo ◽  
Laura D. Kramer
Keyword(s):  
Host Range ◽  
Experimental Evolution ◽  
High Frequency ◽  
Host Shift ◽  
Encephalitis Virus ◽  
Isolation And Characterization ◽  
Vertebrate Cell ◽  
Important Host

Understanding the potential for host range shifts and expansions of RNA viruses is critical to predicting the evolutionary and epidemiological paths of these pathogens. As arthropod-borne viruses (arboviruses) experience frequent spillover from their amplification cycles and are generalists by nature, they are likely to experience a relatively high frequency of success in a range of host environments. Despite this, the potential for host expansion, the genetic correlates of adaptation to novel environments and the costs of such adaptations in originally competent hosts are still not characterized fully for arboviruses. In the studies presented here, we utilized experimental evolution of St. Louis encephalitis virus (SLEV; family Flaviviridae, genus Flavivirus) in vitro in the Dermacentor andersoni line of tick cells to model adaptation to a novel invertebrate host. Our results demonstrated that levels of adaptation and costs in alternate hosts are highly variable among lineages, but also that significant fitness increases in tick cells are achievable with only modest change in consensus genetic sequence. In addition, although accumulation of diversity may at times buffer against phenotypic costs within the SLEV swarm, an increased proportion of variants with an impaired capacity to infect and spread on vertebrate cell culture accumulated with tick cell passage. Isolation and characterization of a subset of these variants implicates the NS3 gene as an important host range determinant for SLEV.

scholarly journals Permanent Draft Genome Sequence of Frankia sp. Strain AvcI1, a Nitrogen-Fixing Actinobacterium Isolated from the Root Nodules of Alnus viridis subsp. crispa Grown in Canada

2015 ◽  
Vol 3 (6) ◽  
Author(s):  
Erik Swanson ◽  
Rediet Oshone ◽  
Stephen Simpson ◽  
Krystalynne Morris ◽  
Feseha Abebe-Akele ◽  
...  
Keyword(s):  
Genome Sequence ◽  
Root Nodules ◽  
Draft Genome ◽  
Draft Genome Sequence ◽  
Nitrogen Fixing ◽  
Alnus Viridis ◽  
Protein Encoding ◽  
Candidate Protein ◽  
Encoding Genes

Frankia strain AvcI1, isolated from root nodules of Alnus viridis subsp. crispa , is a member of Frankia lineage Ia, which is able to reinfect plants of the Betulaceae and Myricaceae families. Here, we report a 7.7-Mbp draft genome sequence with a G+C content of 72.41% and 6,470 candidate protein-encoding genes.

scholarly journals In Vitro Characterization of a Koala Retrovirus

2006 ◽  
Vol 80 (6) ◽  
pp. 3104-3107 ◽  
Author(s):  
Nidia M. Oliveira ◽  
Karen B. Farrell ◽  
Maribeth V. Eiden
Keyword(s):  
Host Range ◽  
Leukemia Virus ◽  
Nucleotide Identity ◽  
Common Source ◽  
Zoonotic Potential ◽  
In Vitro Characterization ◽  
Gibbon Ape Leukemia Virus ◽  
Koala Retrovirus

ABSTRACT Recently, a new endogenous koala gammaretrovirus, designated KoRV, was isolated from koalas. The KoRV genome shares 78% nucleotide identity with another gammaretrovirus, gibbon ape leukemia virus (GALV). KoRV is endogenous in koalas, while GALV is exogenous, suggesting that KoRV predates GALV and that gibbons and koalas acquired the virus at different times from a common source. We have determined that subtle adaptive differences between the KoRV and GALV envelope genes account for differences in their receptor utilization properties. KoRV represents a unique example of a gammaretrovirus whose envelope has evolved to allow for its expanded host range and zoonotic potential.

Evolutionary Diversity of Symbiotically Induced Nodule MADS Box Genes: Characterization of nmhC5, a Member of a Novel Subfamily

1997 ◽  
Vol 10 (5) ◽  
pp. 665-676 ◽  
Author(s):  
Jacqueline Heard ◽  
Michal Caspi ◽  
Kathleen Dunn
Keyword(s):  
Root Nodules ◽  
Consensus Sequence ◽  
Structural Similarity ◽  
Evolutionary Analysis ◽  
Mads Box ◽  
Mads Box Genes ◽  
Mads Box Gene ◽  
Dna Binding Assay

Unique organs called nodules form on legume roots in response to intracellular infection by soil bacteria in the genus Rhizobium. This study describes a new MADS box gene, nmhC5, which along with nmh7 (J. Heard and K. Dunn, Proc. Natl. Acad. Sci. USA 92:5273-5277, 1995), is expressed in alfalfa (Medicago sativa) root nodules. Together, these genes represent the first putative transcription factors identified in nodules. Expression in a root-derived structure supports the growing sentiment that MADS box proteins have diverse roles in plant development. Comparison of the putative translation product of nmhC5 with those of other reported members of the MADS box family suggests that the overall structure of nmhC5 is conserved. Evolutionary analysis among the MADS box family showed that nmhC5 is orthologous to a root-expressed clone in Arabidopsis thaliana, agl17, and that nmh7 is similar to the floral subfamily with AP3 (DefA)/PI (Glo). Consistent with a prediction of homodimer formation, NMHC5 was shown to bind a CArG consensus sequence in vitro. In contrast, NMH7, which shows structural similarity to MADS box proteins that form heterodimers, did not bind the CArG element in an in vitro DNA-binding assay, suggesting the existence of an unknown dimer partner. The root-derived MADS box genes constitute a novel subfamily of vegetatively expressed MADS box genes. The evolutionary diversity between nmh7 and nmhC5 could represent an overall mechanistic conservation between plant developmental processes or could mean that nmh7 and nmhC5 make fundamentally different contributions to the development of the nodule.

scholarly journals Determinants of Host Range Specificity in Legume-Rhizobia Symbiosis

2020 ◽  
Vol 11 ◽  
Author(s):  
Liam Walker ◽  
Beatriz Lagunas ◽  
Miriam L. Gifford
Keyword(s):  
Host Range ◽  
Host Plant ◽  
Molecular Mechanisms ◽  
High Efficiency ◽  
Current Knowledge ◽  
Root Nodules ◽  
Partner Choice ◽  
Nodule Development ◽  
Symbiotic Association ◽  
Nitrogen Fixing

Leguminous plants possess the almost unique ability to enter symbiosis with soil-resident, nitrogen fixing bacteria called rhizobia. During this symbiosis, the bacteria physically colonize specialized organs on the roots of the host plant called nodules, where they reduce atmospheric nitrogen into forms that can be assimilated by the host plant and receive photosynthates in return. In order for nodule development to occur, there is extensive chemical cross-talk between both parties during the formative stages of the symbiosis. The vast majority of the legume family are capable of forming root nodules and typically rhizobia are only able to fix nitrogen within the context of this symbiotic association. However, many legume species only enter productive symbiosis with a few, or even single rhizobial species or strains, and vice-versa. Permitting symbiosis with only rhizobial strains that will be able to fix nitrogen with high efficiency is a crucial strategy for the host plant to prevent cheating by rhizobia. This selectivity is enforced at all stages of the symbiosis, with partner choice beginning during the initial communication between the plant and rhizobia. However, it can also be influenced even once nitrogen-fixing nodules have developed on the root. This review sets out current knowledge about the molecular mechanisms employed by both parties to influence host range during legume-rhizobia symbiosis.

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