Showing papers on "Frankia published in 1990"
TL;DR: One purpose of the study was to compare the densities of infective Frankia in the soil of sites where Betula pendula was growing side by side with Alnus incana, and to determine the nodulation capacity of the soil under birch.
Abstract: The capacity of different soils to induce nodulation in Alnus incana was studied. Soil from stands of different tree species was sampled. The nodulation capacity was determined by inoculating grey alder seedlings growing in liquid culture with 20-fold serial soil dilutions and then counting the nodules formed.
91 citations
TL;DR: In this paper, a set of oligonucleotides was developed to study the competitivity of two Frankia strains in the nodulation of the roots of two host plant species.
Abstract: A set of oligonucleotides has been developed to study the competitivity of two Frankia strains in the nodulation of the roots of two host plant species: Alnus glutinosa and Alnus incana. Two 20 mer-oligonucleotides, complementary to highly conserved sequences inside the nifH gene, were used as primers for the polymerase chain reaction (PCR) system in order to amplify microsymbiont DNA extracted from actinorhizae. PCR products were analyzed using two strain-specific 15-mer oligonucleotides identified in the amplified region. Hybridization data indicate that strain ACoN24d is more competitive than train ArI3 in the nodulation of both hosts.
72 citations
TL;DR: In this article, a method for direct isolation of RNA from a loamy soil and a peat was described for detecting Frankia specific target sequences in RNA isolations from soil.
Abstract: Sequences of 16S rRNA of the nitrogen-fixing Frankia strain Ag45/Mut15 and the ineffective Frankia strain AgB1.9 were used to design a genus-specific oligonucleotide probe. Hybridization experiments of this Frankia probe and a second probe, specific for Nif+-Frankia strains only, were used to detect Frankia specific target sequences in RNA isolations from soil. A method is described for direct isolation of RNA from a loamy soil and a peat. Yields of about 10 ng RNA/g wet soil are obtained without detectable contamination with humic acids. Isolation of RNA after initial extraction of bacteria from soil resulted in significantly lower RNA yields, compared to the direct isolation procedure. Hybridization with both probes against rRNA isolations from Frankia-containing soil could detect target sequences within RNA isolations from 1 g wet soil with an estimated detection limit of 10(4) cells.
70 citations
01 Jan 1990
61 citations
TL;DR: It is apparent that differentiation of vesicles reaches a certain stage of development prior to the onset of nitrogenase synthesis, and FeFe label was not detected in hyphae, appeared in young but was greatest in mature vesicle.
Abstract: SUMMARY
The localization of nitrogenase was studied in root nodules of Alnus incana (L.) Moench in symbiosis with a local source of Frankia. Nodules were fixed in glutaraldehyde and embedded in Epon or LR White. Ultrathin sections were examined by TEM after incubation with antisera against nitrogenase and gold-conjugated secondary antibodies. Antisera against dinitrogenase reductase (Fe-protein) from Rhodospirillum rubrum and dinitrogenase (MoFe-protein) from Azotobacter vinelandii were used. Immunogold label density in hyphae and in spores of Frankia was low and similar to that of plant tissue. Very young vesicles without septa showed a label density of Fe-protein similar to that of hyphae, while young vesicles with a few, usually non-transversing, septa had a significant but still low density of label. Mature vesicles, highly compartmentalised due to transversing septa, contained statistically significantly more Fe-protein label than all other cell types. Old degenerating vesicles always contained nitrogenase, about half as much as that of mature vesicles but often more than young vesicles. Similarly, MoFe label was not detected in hyphae, appeared in young but was greatest in mature vesicles. It is apparent that differentiation of vesicles reaches a certain stage of development prior to the onset of nitrogenase synthesis.
59 citations
01 Jan 1990
48 citations
01 Jan 1990
TL;DR: It was Gibson's belief was that the objective of nitrogen self-sufficiency for agriculturally important plants was most likely to be achieved through symbiotic associations similar to those occurring in legume or actinorhizal nodules.
Abstract: In discussing required inputs from basic studies to applied nitrogen fixation research, Gibson (1) has highlighted three major areas which must be investigated if much of the basic research is to become of practical benefit. These include (i) the development of improved nitrogen fixing strains of rhizobia, cyanobacteria, Azospirillum and Frankia species by molecular biology techniques, coupled with physiological studies relating to the ability of such engineered microorganisms to survive in the soil, (ii) the production, storage, transport and application of inoculants and (iii) the control by the host plant of the development of various symbiotic associations and subsequent nitrogen fixation. His belief was that the objective of nitrogen self-sufficiency for agriculturally important plants was most likely to be achieved through symbiotic associations similar to those occurring in legume or actinorhizal nodules.
45 citations
TL;DR: Oligonucleotide probes that hybridize with specific sequences in variable regions of the 16S rRNA of the nitrogen-fixing actinomycete Frankia were used for the identification of Frankia strains in nodules and the utility of this rRNA extraction method was tested in a competition experiment between two effective Frankia strain on cloned Alnus glutinosa plants.
Abstract: Oligonucleotide probes that hybridize with specific sequences in variable regions of the 16S rRNA of the nitrogen-fixing actinomycete Frankia were used for the identification of Frankia strains in nodules. Frankia cells were released from plant tissue by grinding glutaraldehyde-fixed root nodules in guanidine hydrochloride solution. rRNA was obtained after sonication, precipitation with ethanol, and purification by phenolchloroform extraction. Degradation of rRNA, evident in Northern blots, did not affect hybridization with the oligonucleotides. Nodules of about 1 mg (fresh weight) provided sufficient rRNA for reliable detection of the Frankia strain. The utility of this rRNA extraction method was tested in a competition experiment between two effective Frankia strains on cloned Alnus glutinosa plants.
38 citations
01 Jan 1990
33 citations
TL;DR: The Frankia glnII gene product has a high degree of similarity with both GSII from B. japonicum and GS from pea, although the sequence was about equally similar to both the bacterial and eucaryotic proteins.
Abstract: In common with other plant symbionts, Frankia spp, the actinomycete N2-fixing symbionts of certain nonleguminous woody plants, synthesize two glutamine synthetases, GSI and GSII DNA encoding the Bradyrhizobium japonicum gene for GSII (glnII) hybridized to DNA from three Frankia strains B japonicum glnII was used as a probe to clone the glnII gene from a size-selected KpnI library of Frankia strain CpI1 DNA The region corresponding to the Frankia sp strain CpI1 glnII gene was sequenced, and the amino acid sequence was compared with that of the GS gene from the pea and glnII from B japonicum The Frankia glnII gene product has a high degree of similarity with both GSII from B japonicum and GS from pea, although the sequence was about equally similar to both the bacterial and eucaryotic proteins The Frankia glnII gene was also capable of complementing an Escherichia coli delta glnA mutant when transcribed from the vector lac promoter, but not when transcribed from the Frankia promoter GSII produced in E coli was heat labile, like the enzyme produced in Frankia sp strain CpI1 but unlike the wild-type E coli enzyme
TL;DR: The soil bacterium Frankia of the Actinomycetales, capable of forming N(2)-fixing symbiotic root nodules on a diverse array of actinorhizal plants, has several morphological forms when grown in pure culture.
Abstract: The soil bacterium Frankia of the Actinomycetales, capable of forming N2-fixing symbiotic root nodules on a diverse array of actinorhizal plants, has several morphological forms when grown in pure culture. Fresh hydrated preparations of whole cells, hyphae, and spores were all infective on seedlings of Casuarina at different dilutions. Desiccated hyphae showed no infection capacity, while desiccated spores remained infective, although at a reduced level. On the basis of most-probable-number statistics, spore suspensions were 3 orders of magnitude more infective than hyphae.
01 Jan 1990
01 Jan 1990
TL;DR: The numbers of lipid laminae were observed to increase significantly in the distal regions of the symbiotic vesicles in response to raised pO2 while the numbers on the proximal portions remained unchanged.
Abstract: Nodulated plants of Alnus incana ssp. rugosa and ssp. incana were grown with the roots exposed to 5, 21, and 40 kPa O2. The nodules were studied by freeze-fracture transmission electron microscopy to determine the effect of varying O2 tension on the numbers of lipid laminae in the Frankia envelope. Lipid laminae were present in the cell envelopes of hyphae, stalks, and symbiotic vesicles. The mean number of lipid laminae in hyphal envelopes varied from five to nine. Stalks of symbiotic vesicles contained mean numbers of 35–59 lipid laminae over the range of pO2's studied. Symbiotic vesicle envelopes showed mean numbers of lipid laminae varying from 48 to 94. The numbers of lipid laminae were observed to increase significantly in the distal regions of the symbiotic vesicles in response to raised pO2 while the numbers on the proximal portions remained unchanged. The increase in the numbers of lipid laminae in response to raised pO2 was not sufficient to account for the expected increase in resistance to O2 ...
TL;DR: Oxygen-induced nitrogenase transients in actinorhizal nodules from the plant genera tested here do not appear to be a result of changes in nodule diffusion resistance, and are purely a response by the bacterium and not a nodule effect per se.
Abstract: Nitrogenase activity in root nodules of four species of actinorhizal plants showed varying declines in response to exposure to acetylene (10% v/v). Gymnostoma papuanum (S. Moore) L. Johnson. and Casuarina equisetifolia L. nodules showed a small decline (5-15%) with little or no recovery over 15 minutes. Myrica gale L. nodules showed a sharp decline followed by a rapid return to peak activity. Alnus incana ssp. rugosa (Du Roi) Clausen. nodules usually showed varying degrees of decline followed by a slower return to peak or near-peak activity. We call these effects acetylene-induced transients. Rapid increases in oxygen tension also caused dramatic transient decreases in nitrogenase activity in all species. The magnitude of the transient decrease was related to the size of the O2 partial pressure (pO2) rise, to the proximity of the starting and ending oxygen tensions to the pO2 optimum, and to the time for which the plant was exposed to the lower pO2. Oxygen-induced transients, induced both by step jumps in pO2 and by O2 pulses, were also observed in cultures of Frankia. The effects seen in nodules are purely a response by the bacterium and not a nodule effect per se. Oxygen-induced nitrogenase transients in actinorhizal nodules from the plant genera tested here do not appear to be a result of changes in nodule diffusion resistance.
TL;DR: The isolate of Frankia designated HFPCgI4 was isolated from root nodules collected in Egypt and its characteristics assessed both in pure culture and in symbiosis, finding it to have use as an inoculant for forest plantations using species of Casuarina sensu stricta.
Abstract: Casuarina glauca (Casuarinaceae) is an important introduced tree species in Egypt, valued for windbreaks, land stabilization, and soil improvement associated with actinomycete-induced root nodules ...
TL;DR: The richness of the Frankia amino-peptidase and esterases zymograms makes them adequate marker enzymes for taxonomical, genetic, or biochemical studies, and a nomenclature is proposed for aminopeptidases and other Frankia enzymes.
TL;DR: Vesicles apparently lack a complete pathway for assimilating ammonia beyond the glutamine stage as shown by enzyme assay and two-dimensional polyacrylamide gel electrophoresis.
Abstract: Frankia spp. are filamentous actinomycetes that fix N2 in culture and in actinorhizal root nodules. In combined nitrogen-depleted aerobic environments, nitrogenase is restricted to thick-walled spherical structures, Frankia vesicles, that are formed on short stalks along the vegetative hyphae. The activities of the NH4(+)-assimilating enzymes (glutamine synthetase [GS], glutamate synthase, glutamate dehydrogenase, and alanine dehydrogenase) were determined in cells grown on NH4+ and N2 and in vesicles and hyphae from N2-fixing cultures separated on sucrose gradients. The two frankial GSs, GSI and GSII, were present in vesicles at levels similar to those detected in vegetative hyphae from N2-fixing cultures as shown by enzyme assay and two-dimensional polyacrylamide gel electrophoresis. Glutamate synthase, glutamate dehydrogenase, and alanine dehydrogenase activities were restricted to the vegetative hyphae. Vesicles apparently lack a complete pathway for assimilating ammonia beyond the glutamine stage.
01 Jan 1990
TL;DR: The growth of Frankia in the rhizosphere of Betula pendula was studied to understand the favourable effect of this nonhost species on Alnus-nodulating Frankia as well as Indole-3-ethanol in soil.
Abstract: The growth of Frankia in the rhizosphere of Betula pendula was studied to understand the favourable effect of this nonhost species on Alnus-nodulating Frankia in soil. Axenic Betula pendula and Alnus incana seedlings were inoculated with Frankia strains. The development of Frankia in the rhizosphere was examined by light and scanning electron microscopy. Some Frankia strains grew in the rhizosphere of Betula pendula seedlings without addition of a carbon and energy source. In addition to hyphae and sporangia, vesicles were also formed. Growth (if any) was more local and less abundant in the rhizosphere of Alnus incana seedlings. Frankia strains were grown in defined medium supplemented with tryptophan. Indole-3-ethanol was detected in the culture solution by gas chromatography – mass spectrometry. Key words: Alnus incana, Betula pendula, Frankia, indole-3-ethanol.
TL;DR: An ineffective strain type of Frankia of unknown strain composition, coded AgI-WD1 was discovered in the soil of wet dune slacks where A. glutinosa was the dominant tree species and the contribution of this strain type to soil populations ofFrankia was demonstrated by nodulation potentials that were up to 500 times higher than that of the concurrent effective strain type AgSp-.
Abstract: An ineffective strain type of Frankia of unknown strain composition, coded AgI-WD1 was discovered in the soil of wet dune slacks where A. glutinosa was the dominant tree species.
TL;DR: IRA appeared to reflect the ‘metabolically active’ biomass of Frankia more accurately than the Bradford protein estimations.
Abstract: The growth of Frankia spp. strain ORS 020607 in BAP medium was studied by using two methods simultaneously: determination of Bradford protein content and INT (2-(p-iodophenyl-3-(p-nitrophenyl)-5-phenyl tetrazoliumchloride) reduction activity (IRA). With the latter test, red formazan crystals formed intracellularly were extracted with methanol. Colouration intensity was estimated by absorbance spectrophotometry at 490 nm. The protein content and IRA of the culture were monitored for 96 days. IRA appeared to reflect the ‘metabolically active’ biomass of Frankia more accurately than the Bradford protein estimations.
TL;DR: Investigations on the ecological function of ineffective Frankia strains and their behaviour in competition with effectiveFrankia strains indicated an enhanced plant growth upon dual inoculation with increasing amounts of effective (i.e. N2-fixing)Frankia strain.
Abstract: Investigations on the ecological function of ineffectiveFrankia strains and their behaviour in competition with effectiveFrankia strains indicated an enhanced plant growth upon dual inoculation with increasing amounts of effective (i.e. N2-fixing)Frankia strains and simultaneous inoculation with a constant amount of an ineffectiveFrankia strain. Enhanced plant growth was measured as increase in plant height and total dry weight at constant shoot/root ratio. The stimulating effect of the ineffective strain was independent of the plant clone and was obtained with bothAlnus glutinosa clones W I and B II, which were resistant and susceptable, respectively, to the ineffective strain. Stimulation was also independent of the nodulation conditions. Short-term studies (7 weeks) under axenic conditions and greenhouse experiments during 3 months showed comparable results, not only in plant growth but also in nodule formation. Increment in plant growth was not necessarily correlated to higher nodule formation with the effectiveFrankia strains.
TL;DR: All the Frankia sources contained a hydrogenase protein, even the local source where no in vivo or in vitro activity could be measured, and immunogold localization of the protein demonstrated that in both the symbiotic state and the free-living nitrogen-fixing Frankia, the protein is located in vesicles and in hyphae.
Abstract: Symbiotic and free-living Frankia were investigated for correlation between hydrogenase activities (in vivo/in vitro assays) and for occurrence and localization of hydrogenase protein by Western blots and immuno-gold localization, respectively. Freshly prepared nodule homogenates from the symbiosis between Alnus incana and a local source of Frankia did not show any detectable in vivo or in vitro hydrogenase uptake activity, as also has been shown earlier. However, a free-living Frankia strain originally isolated from these nodules clearly showed both in vivo and in vitro hydrogenase activity, with the latter being approximately four times higher. Frankia strain Cpl1 showed hydrogen uptake activity both in symbiosis with Alnus incana and in a free-living state. Western blots on the different combinations of host plants and Frankia strains used in the present study revealed that all the Frankia sources contained a hydrogenase protein, even the local source where no in vivo or in vitro activity could be measured. The 72 kilodalton protein found in the symbiotic Frankia as well as in the free-living Frankia strains were immunologically related to the large subunit of a dimeric hydrogenase purified from Alcaligenes latus. Recognitions to polypeptides with molecular masses of about 41 and 19.5 kilodaltons were also observed in Frankia strain UGL011101 and in the local source of Frankia, respectively. Immunogold localization of the protein demonstrated that in both the symbiotic state and the free-living nitrogen-fixing Frankia, the protein is located in vesicles and in hyphae. The inability to measure any uptake hydrogenase activity is therefore not due to the absence of hydrogenase enzyme. However, the possibility of an inactive hydrogenase enzyme cannot be ruled out.
01 Jan 1990
TL;DR: An important finding was that some strains of rhizobia can nodulate both legumes and Parasponia suggesting that the widely differing nodulation processes are largely plant determined and require the correct trigger(s) fromrhizobia or Frankia.
Abstract: Naturally occurring rhizobia in the soil form nodules on legumes and not on non-legumes with the exception of Parasponia, a member of the Ulmaceae family (1). Induction of legume nodules by rhizobia involves a multi step interaction, following an exchange of signals between the Rhizobium strain and its host (2,3,4). Parasponia nodulation resembles the nitrogen-fixing root nodulation formed between other non-legumes and actinomycetes of the genus Frankia. In non-legumes, nodule formation requires the initiation of cell division within the root cortex followed by the induction of a lateral root below the site of cell division The final structure is a lateral root swollen on either side of the central vascular tissue by cortical cells filled with bacteria actively engaged in nitrogen fixation. An important finding was that some strains of rhizobia can nodulate both legumes and Parasponia suggesting that the widely differing nodulation processes are largely plant determined and require the correct trigger(s) from rhizobia or Frankia.
01 Jan 1990
TL;DR: It is evident that competitive ability varies with strains and that effectiveness is affected even if nodulated plants are transplanted into soil, and some soil factors possibly negatively affecting the persistence of introduced Sp − Frankia strain are discussed.
Abstract: The behaviour of a Sp + and a Sp − strain of Frankia for nodulation and N 2 -fixation in Alnus incana with pure and mixed inocula was investigated under greenhouse conditions, using spore formation as a morphological marker for strain recognition. The results showed that, in an artificial medium, both strains coexisted on the same root system, but the Sp − strain exhibited greater specific activity (N 2 -fixation) that the Sp + strain. When a Sp − strain was introduced into soil containing indigenous Sp + Frankia , a low proportion of nodules were formed by the new strain and exhibited lower specific activity than Sp + nodules. It is evident that competitive ability varies with strains and that effectiveness is affected even if nodulated plants are transplanted into soil. Some soil factors possibly negatively affecting the persistence of introduced Sp − Frankia strain are discussed.