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  • 1
    Electronic Resource
    Electronic Resource
    Competition for Nodulation of Legumes (1986)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Microbiology 40 (1986), S. 131-157 
    Details
    ISSN: 0066-4227
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.mi.40.100186.001023
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  • 2
    Electronic Resource
    Electronic Resource
    Sulphation of Rhizobium sp. NGR234 Nod factors is dependent on noeE, a new host-specificity gene (1997)
    Oxford UK : Blackwell Science Ltd
    Molecular microbiology 24 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Rhizobia secrete specific lipo-chitooligosaccharide signals (LCOs) called Nod factors that are required for infection and nodulation of legumes. In Rhizobium sp. NGR234, the reducing N-acetyl-d-glucosamine of LCOs is substituted at C6 with 2-O-methyl-l-fucose which can be acetylated or sulphated. We identified a flavonoid-inducible locus on the symbiotic plasmid pNGR234a that contains a new nodulation gene, noeEwhich is required for the sulphation of NGR234 Nod factors (NodNGR). noeE was identified by conjugation into the closely related Rhizobium fredii strain USDA257, which produces fucosylated but non-sulphated Nod factors (NodUSDA). R. fredii transconjugants producing sulphated LCOs acquire the capacity to nodulate Calopogonium caeruleum. Furthermore, mutation of noeE (NGRΔnoeE ) abolishes the production of sulphated LCOs and prevents nodulation of Pachyrhizus tuberosus. The sulphotransferase activity linked to NoeE is specific for fucose. In contrast, the sulphotransferase NodH of Rhizobium meliloti seems to be less specific than NoeE, because its introduction into NGRΔnoeE leads to the production of a mixture of LCOs that are sulphated on C6 of the reducing terminus and sulphated on the 2-O-methylfucose residue. Together, these findings show that noeE is a host-specificity gene which probably encodes a fucose-specific sulphotransferase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3981777.x
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  • 3
    Electronic Resource
    Electronic Resource
    Broad-host-range Rhizobium species strain NGR234 secretes a family of carbamoylated, and fucosylated, nodulation signals that are O-acetylated or sulphated (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 6 (1992), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Rhizobium species strain NGR234 is the most promiscuous known rhizobium. In addition to the non-legume Parasponia andersonii, it nodulates at least 70 genera of legumes. Here we show that the nodulation genes of this bacterium determine the production of a large family of Nod-factors which are N-acylated chitin pentamers carrying a variety of substituents. The terminal non-reducing glucosamine is N-acylated with vaccenic or palmitic acids, is N-methylated, and carries varying numbers of carbamoyl groups. The reducing N-acetyl-glucosamine residue is substituted on position 6 with 2-O-methyl-L-fucose which may be acetylated or sulphated or non-substituted. All three internal residues are N-acetylated. At pico- to nanomolar concentrations, these signal molecules exhibit biological activities on the tropical legumes Macroptilium and Vigna (Phaseoleae), as well as on both the temperate genera Medicago (Trifoliae) and Vicia (Viciae). These data strongly suggest that the uniquely broad host range of NGR234 is mediated by the synthesis of a family of varied sulphated and non-sulphated lipo-oligosaccharide signals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1992.tb01793.x
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  • 4
    Electronic Resource
    Electronic Resource
    Organization of host-inducible transcripts on the symbiotic plasmid of Rhizobium sp. NGR234 (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 16 (1995), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: In a systematic approach to identify genes involved in the early steps of the legume—Rhizobium symbiosis, we studied transcription patterns of symbiotic plasmid-borne loci. A competitive hybridization procedure was used to identify DNA restriction fragments carrying genes whose expression is enhanced by plant root exudates or by purified flavonoids. Fragments containing induced genes were then located on the physical map of the 500 kb pNGR234a. New inducible loci as well as previously described genes were identified and their time course of induction determined. After initial induction, transcription of loci such as nodABC and the host-specificity genes nodSU decreased to undetectable levels 24 h after incubation with purified flavonoids. In contrast, expression of other loci is detectable only after several hours of induction. Surprisingly, many genes remained transcribed in the nodD1 mutant suggesting the presence of other flavonoid-dependent activators in NGR234. The hsnl region, which is involved in host specificity, was shown to carry several inducible but independently regulated transcripts. Sequencing analysis revealed several open reading frames whose products, based on sequence similarities, may be involved in L-fucose metabolism and its adjunction to the Nod factors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1995.tb02428.x
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  • 5
    Electronic Resource
    Electronic Resource
    Nod factors of Rhizobium are a key to the legume door (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 13 (1994), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Symbiotic interactions between rhizobia and legumes are largely controlled by reciprocal signal exchange. Legume roots excrete flavonoids which induce rhizobial nodulation genes to synthesize and excrete lopo-oligosaccharide Nod factors. In turn, Nod factors provoke deformation of the root hairs and nodule primordium formation. Normally, rhizobia enter roots through infection threads in markedly curled root hairs. If Nod factors are responsible for symbiosis-specific root hair deformation, they could also be the signal for entry of rhizobia into legume roots. We tested this hypothesis by adding, at inoculation, NodNGR-factors to signal-production-deficient mutants of the broad-host-range Rhizobium sp. NGR234 and Bradyrhizobium japorticum strain USDA110. Between 10 −7 M and 10−6 M NodNGR factors permitted these NodABC mutants to penetrate, nodulate and fix nitrogen on Vigna unguiculata and Glycine max, respectively. NodNGR factors also allowed Rhizobium fredii strain USDA257 to enter and fix nitrogen on Calopogonium caeruleum, a non-host. Detailed cytological investigations of V. unguiculata showed that the NodABC mutant UGR AnodABC, in the presence of NodNGR factors, entered roots in the same way as the wild-type bacterium. Since infection threads were also present in the resulting nodules, we conclude that Nod factors are the signals that permit rhizobia to penetrate legume roots via infection threads.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1994.tb00412.x
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  • 6
    Electronic Resource
    Electronic Resource
    Differential expression of nodS accounts for the varied abilities of Rhizobium fredii USDA257 and Rhizobium sp. strain NGR234 to nodulate Leucaena spp. (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 6 (1992), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Transfer of a cosmid containing nodSU from Rhizobium sp. NGR234 to Rhizobium fredii USDA257 expands the host range for nodulation to include the perennial tropical legumes, Leucaena leucocephala and Leucaena diversifolia. Complementation experiments with a series of subclones established that nodS and its associated nod-box promoter from NGR234 are sufficient to confer this extended host-range phenotype to L. leucocephala. Strain USDA257 contains its own copy of nodSU, including upstream nod-box sequences. Although both nucleotide and deduced amino acid sequences of the reading frames are homologous between the two strains, there are gaps within the promoter region and the 5′-end of nodS of USDA257. Consequently, the deduced NodS protein of USDA2S7 is shorter than its counterpart from NGR234, and the distance between the nod-box and the initiation codon is greater. A 36 bp deletion encompasses the extreme right border of the USDA257 nod-box and extends into the upstream leader sequence. Transcriptional fusions with both nod-boxes confirmed that the promoter from NGR234 is flavonoid-inducible, and that the nod-box from USDA257 is not. These observations were corroborated by Northern analysis with a nodS-containing Xhol fragment as hybridization probe. Flavonoid-induced cells of NGR234 gave an intense signal, but those of USDA257 yielded only a weak trace of hybridization. EcoRl fragments with homology to nodSU of USDA257 are present in 17 of 35 tested strains, including several representatives ofBradyrhizobium japonicum, Rhizobium sp., R. loti, and R. fredii. Two wild-type, leucaena-nodulating strains of Rhizobium sp. lack this homology. We conclude that a genetic defect in expression of nodS accounts for the inability of USDA257 to nodulate leucaena and that diverse rhizobia may have evolved alternative mechanisms to nodulate this legume species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1992.tb02200.x
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  • 7
    Electronic Resource
    Electronic Resource
    Regeneration of whole plants from hypocotyl-, root-, and leaf-derived tissue cultures of the pasture legume Stylosanthes guyanensis (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 52 (1981), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Callus cultures were established on Murashige and Skoog medium from seedling hypocotyls and roots of Slylosanlhes guyanensis (Aubl.) Sw. cv. Cook and from leaves of 6-month-old) plants. Shoots developed in primary calli derived from seedling tissue with a number of benzyladenine or kinetin and naphthaleneacetic acid combinations. Shoot formation on primary leaf callus, occurred with 2.0 mg/1 benzyladenine and 2.0 or 1.0 mg/l naphthaieneacetic acid. Undifferentiated callus from all three sources was induced and maintained on medium with 2.0 mg/1 kinetin and 2.0 mg/1 2, 4-dichlorophenoxyacede acid in the dark. Shoot formation and regeneration of whole plants from these calli were achieved at high frequencies. The most successful combination of phytohormones for the induction of shoot development in undifferentiated callus, was 2.0 mg/1 benzyladenine and 1.0 mg/1 naphthaleneacetic acid. The regenerated plants showed no phenotypic abnormalities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1981.tb08506.x
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  • 8
    Electronic Resource
    Electronic Resource
    Acetylene reduction by legume root nodule protoplasts (1976)
    [s.l.] : Nature Publishing Group
    Nature 262 (1976), S. 208-209 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Protoplasts were isolated in a medium containing the following: 1% (w/v) Rhozyme HP 150 (Rohm and Haas); 0.5% (w/v) pectin lyase (EC 4.2.2.3 (ref. 8), Kikkoman Shoyu, Chiba-ken, Japan); 1% (w/v) cellulase (EC 3.2.1.4) (Onozuka R-10, Kinki Yakult Co., Tokyo); 1% (w/v) bovine serum albumin (Sigma) ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/262208a0
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  • 9
    Electronic Resource
    Electronic Resource
    Effects of fruit on ribulosediphosphate carboxylase activity inCitrus madurensis leaves (1973)
    Springer
    Cellular and molecular life sciences 29 (1973), S. 271-272 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung An fruchtenden und entblüteten Stecklingen vonCitrus madurensis wurde an vergleichbar inserierten Blättern die Aktivität von Ribulose-Diphosphat carboxylase und der Gehalt an löslichen Proteinen bestimmt. Sowohl die Aktivität von RuD Carboxylase als auch der Gehalt an löslichen Proteinen waren in Plättern fruchtender höher als in solchen nicht fruchtender Planzen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01926469
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  • 10
    Electronic Resource
    Electronic Resource
    Development of the nitrogen fixing apparatus in the legumes, Centrosema pubescens Benth., and Vigna unguiculata L. Walp. (1978)
    Springer
    Planta 139 (1978), S. 183-192 
    Details
    ISSN: 1432-2048
    Keywords: Centrosema leghaemoglobin ; Nitrate reductase ; Nitrogen fixation ; Nitrogenase ; Vigna
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The sequence of events leading up to the establishment of symbiotic nitrogen-fixation were studied in two tropical legumes, Centrosema pubescens Benth, and Vigna unguiculata L. Walp. Parameters measured included fresh and dry weights, chlorophyll and leghaemoglobin contents, as well as the activities of NADH-nitrate reductase (EC 1.6.6.1), and nitrogenase (nitric-oxide reductase-EC 1.7.99.2) in plants that were inoculated with suitable rhizobia or which were watered with potassium nitrate. Dry weight and photosynthetic activity of both species followed the sigmoidal pattern which is characteristic of most plants. Growth was little different in either a qualitative or quantitative sense whether nitrogen was supplied as nitrate or through dinitrogen fixation. Although the biochemical sequence of events was dependent on the limiting sensitivities of the individual assays used, the data suggest that nitrate reductase is the first measurable enzymatic activity in the nodules (and roots), followed by acetylene reduction and leghaemoglobin in that order. It is possible therefore, that low levels of symbiotic nitrogen fixation occur in the nodules in the absence of leghaemoglobin. Nitrate reductase activity in C. pubescens nodules was negatively exponentially correlated with nitrogenase activity of the same nodules, suggesting a changing metabolism in old nodules. These data are discussed in terms of environmental and physical factors known to control nitrogen fixation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00387146
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