Showing papers on "Frankia published in 1988"

Functioning haemoglobin genes in non-nodulating plants

Abstract: Haemoglobin has previously been recorded in plants only in the nitrogen-fixing nodules formed by symbiotic association between Rhizobium or Frankia and legume or non-legume hosts. Structural similarities amongst these and animal haemoglobins at the protein and gene level suggested a common evolutionary origin. This suggests that haemoglobin genes, inherited from an ancestor common to plants and animals, might be present in all plants. We report here the isolation of a haemoglobin gene from Trema tomentosa, a non-nodulating relative of Parasponia (Ulmaceae). The gene has three introns located at positions identical to those in the haemoglobin genes of nodulating plant species, strengthening the case for a common origin of all plant haemoglobin genes. The data argue strongly against horizontal haemoglobin gene transfer from animals to plants. The Trema gene has a tissue-specific pattern of transcription and translation, producing monomeric haemoglobin in Trema roots. We have also found that the Parasponia haemoglobin gene is transcribed in roots of non-nodulated plants. These results suggest that haemoglobin has a role in the respiratory metabolism of root cells of all plant species. We propose that its special role in nitrogen-fixing nodules has required adaptation of the haemoglobin-gene regulation pathway, to give high expression in the specialized environment of the nodule.

Conservation of nif sequences in Frankia

Abstract: Southern blots of Frankia total DNAs were hybridized with nifHDK probes from Rhizobium meliloti, Klebsiella pneumoniae and Frankia strain Arl3 Differences between strains were noted in the size of the hybridizing restriction fragments These differences were more pronounced among Elaeagnus-compatible strains than among Alnus- or Casuarina-compatible strains Gene banks constructed for Frankia strains EUN1f, HRN18a, CeD and ACoN24d were used to isolate nif-hybridizing restriction fragments for subsequent mapping and comparisons The nifH zone had the highest sequence conservation and the nifH and nifD genes were found to be contiguous The complete nucleotide sequence of the nifH open reading frame (ORF) from Frankia strain Arl3 is 861 bp in length and encodes a polypeptide of 287 amino acids Comparisons of these nucleic acid and amino acid sequences with other published nifH sequences suggest that Frankia is most similar to Anabaena and Azotobacter spp and K pneunoniae and least similar to the Gram-positive Clostridium pasteurianum and to the archaebacterium Methanococcus voltae

Variable compatibility of cloned Alnus glutinosa ecotypes against ineffective Frankia strains.

Abstract: Nodulation tests onin-vitro propagated clones ofAlnus glutinosa ecotypes (forest ecotype, pioneer ecotype) withFrankia strains originating from both ecotypes indicated differences in host-plant compatibility. Inoculated plants of the pioneer ecotype clone were not infected by strains, that were unable to fix nitrogen in pure culture. Nodulation could only be induced on the clone of the forest ecotype, but no nitrogen-fixing activity could be detected. Ultra-structural observations of the nodules by SEM and TEM indicated that ineffectivity of these strains was correlated with the lack of vesicles in the infected cells. Cells were only filled with hyphae: neither sporangia nor vesicles could be detected. In contrast, effective nodules could be obtained on both alder clones after inoculation with an effective strain, showing normal development of vesicle clusters in infected cells. In pure culture the ineffective strains produced no vesicles; sporangia were found only during early stage of growth. The results demonstrate the existence ofFrankia strains which were either non-infective or ineffective on different clones ofAlnus glutinosa.

Cytokinin Secretion by Frankia sp. HFP ArI3 in Defined Medium

Abstract: Frankia sp. HFP ArI3 (host plant Alnus rubra Bong.) was grown in defined medium and the culture solution was analyzed for the presence of various cytokinins and related compounds. N6- (Δ2-isopentenyl) adenosine was the only cytokinin detected by both high performance liquid chromatography and gas chromatography-mass spectrometry, at levels of approximately 1 ng/ml culture medium.

Presence and dispersal of infective Frankia in peat and meadow soils in Sweden

Abstract: Use of the N2-fixing grey alder, Alnus incana (L.) Moench, as a short-rotation crop for energy production is currently being explored. To evaluate the need for inoculation of alders, the distribution of infective propagules of Frankia in the soil at potential sites for alder plantations was examined. Uninoculated grey alder seedlings were grown in three types of soil. Frequent nodulation was found in a meadow soil which had been free from actinorhizal plants for nearly 60 years, but the alder seedlings failed to nodulate in peat soil from two different bog sites. One of these bogs had been exploited for peat and the surface layer of the peat had been removed, so that the soil samples were taken from deep layers of the peat. At the other site, an area of cultivated peat, there were no infective propagules of Frankia in plots without alders; the infective Frankia was present in plots only where it had been introduced by inoculated alders. There was no detectable air-borne dispersal of Frankia. Instead, water movement might account for the dispersal of Frankia in peat. Although the apparent absence of Frankia in these peat soils necessitates inoculation of alder seedlings before planting out, this makes it possible to introduce and maintain Frankia strains with selected beneficial characteristics, since there is no competition from an indigenous Frankia flora.

Growth responses in Casuarina cunninghamiana plantings to inoculation with Frankia

Abstract: Growth responses ofCasuarina cunninghamiana to inoculation withFrankia are described in unsterilized field soils at three sites

Survival of Frankia strains introduced into soil

Abstract: Factors affecting the establishment of Alnus/Frankia symbioses were studied partly by following the survival ofFrankia strains exposed to different soil conditions, and partly by investigating the effect of pH on nodulation. TwoFrankia strains were used, both of the Sp− type (sporangia not formed in nodules). One of the strains sporulated heavily, while the other formed mainly hyphae. The strains originated fromAlnus incana root nodules growing in soils of pH 3.5 and 5.0. The optimum pH for their growth in pure culture was found to be 6.7 and 6.2, respectively.

Host range differentiation of spore‐positive and spore‐negative strain types of Frankia in stands of Alnus glutinosa and Alnus incana in Finland

Abstract: Host compatibility of different spore-positive (Sp+)and spore-negative (Sp−) strain types of Frankia from alder stands in Finland was studied in Modulation tests with hydrocultures of Alnus glutinosa (L.) Gaertner, A. incana (L.) Moench and A. nitida Endl. Root nodules and soil samples from stands of A. incana (Lammi forest and Hameenlinna forest) were dominated by Sp + types of Frankia (coded AiSp+ and AiSp+ H. respectively), which caused effective root nodules in test plants of A. incana, but failed to induce nodules in A. nitida. In A. glutinosa Frankia strain types AiSp + and AiSp + H caused small, ineffective root nodules with sporangia (coded Ineff −), which were recognized by the absence or near absence of vesicles in the nodule tissue. Ineffective nodules without sporangia (coded Ineff −) were induced on A. glutinosa with soil samples collected at Lammi swamp. The spore-negative strain type of Frankia was common in root nodules of A. glutinosa in Finland (Lammi swamp) and caused effective Sp− type root nodules (coded AgSp −) in hydrocultures of A. incana, A. glutinosa and A. nitida. A different Sp + strain type of Frankia. coded AgSp+ Finland, was occasionally found in stands of A. glutinosa. It was clearly distinguished from strain type AiSp + by the ability to produce effective nodules on both A. glutinosa and A. incana. The nodulation capacities of soil and nodule samples were calculated from the nodulation response in hydrocutlure and served as a measure for the population density of infective Frankia particles. Sp + nodules from both strain types had equal and high nodulation capacities with compatible host species. The nodulation capacities of Sp type root nodules from A. glutinosa were consistently low. High frequencies of Frankia AiSp+ and AiSp+ H were found in the soil environment of dominant AiSp + nodule populations on A. incana. The numbers of infective particles of this strain type were insignificant in the soil environment of nearby Sp − nodule populations on A. glutinosa and in the former field at Hameen-linna near the Sp+ nodule area in Hameenlinna forest. Strain type AgSp− had low undulation capacity in the soil environment of both A. incana and A. glutinosa stands, Explanations for the strong associations between Frankia strain types AiSp+ and AiSp − H and A. incana and between strain type AgSp− and A. glutinosa are discussed in the light of host specificity and of some characteristics of population dynamics of both strain types. The possible need to adapt the concept of Frankia strain types Sp + and Sp − to strains with some variation in spore development was stressed by the low potentials of strain type AiSp + H to develop spores in symbioses with hydrocultures of A. incnna.

Growth, nodule morphology, and nitrogenase activity of Myrica gale with roots grown at various oxygen levels

Abstract: Myrica gale L. plants were inoculated with Frankia strain HFP M+g15 and grown for 28 days with root systems exposed to 2, 5, 10, 21, and 40 kPa O2. Plant growth was similar under all treatments, ex...

Adaptation of nitrogenase to varying oxygen tension and the role of the vesicle in root nodules of Alnus incana ssp. rugosa

Abstract: Growth of Alnus incana ssp. rugosa plants with root systems at Po2 levels of 5, 21, and 40 kPa showed no significant differences among treatments over a 6-week period. Nitrogenase activity of attac...

Identification of frankia strains by direct DNA hybridization of crushed nodules.

Abstract: A hybridization procedure was developed to identify Frankia strains inside actinorhizae by direct probing of crushed root nodules. The probe consisted of an indigenous cryptic plasmid. This well-conserved, 8-kilobase plasmid was detected in Frankia isolates that were very close taxonomically (they possessed a very high DNA sequence homology). The probe did not hybridize to the DNA of Frankia isolates which did not carry the plasmid. Endophyte DNA was extracted by a modification of a technique originally developed for the detection of plasmids in Frankia isolates. The hybridization procedure applied to nodules collected in a stand of alder permitted determination of a distribution map of the plasmid-bearing Frankia strains.

Glasshouse evaluation of the growth of Alnus rubra and Alnus glutinosa on peat and acid brown earth soils when inoculated with four sources of Frankia

Abstract: The effects of soil type (an acid peat and 2 acid brown earths) andFrankia source (3 spore-positive crushed nodule inocula and spore-negative crushed nodules containing the singleFrankia ArI5) on nodulation, N content and growth ofAlnus glutinosa andA. rubra were determined in a glasshouse pot experiment of two years duration. Plants on all soils required additional P for growth. Growth of both species was very poor on peat withA. glutinosa superior toA. rubra. The former species was also superior toA. rubra on an acid brown earth with low pH and low P content. Some plant-inoculum combinations were of notable effectivity on particular soils but soil type was the major source of variation in plant weight. Inoculation with crushed nodules containingFrankia ArI5 only gave poor infection of the host plant, suggesting that inoculation with locally-collected crushed nodules can be a preferred alternative to inoculation withFrankia isolates of untested effectivity. Evidence of adaptation ofFrankia to particular soils was obtained. Thus, while the growth of all strains was stimulated by mineral soil extracts, inhibitory effects of peat extracts were more apparent with isolates from nodules from mineral soils than from peat, suggesting that survival ofFrankia on peat may be improved by strain selection.

Heterologous hybridization of Frankia DNA to Rhizobium meliloti and Klebsiella pneumoniae nif genes

Abstract: A nif gene probe from Rhizobium meliloti was used to isolate a recombinant bacteriophage from a Frankia sp. ArI3 gene bank. There is a large homology between nifD and nifH genes of R. meliloti or Klebsiella pneumoniae and Frankia DNA sequences. Approximately 4.5 kb to the right of nifK, we have localized a DNA region hybridizing to a R. meliloti probe containing nifA and nifB genes. The extent of the homology was greater for nifB than for nifA.

Effects of elevated oxygen tensions on acetylene reduction in Alnus incana-Frankia symbioses

Abstract: An open flow-through gas system was used to determine the effect of C2H2 and elevated O2 on acetylene reduction activity (ARA) and respiration of the intact, potted root system of Alnus incana (L.) Moench in symbiosis with Frankia Avcll or with a local source of Frankia. Both symbiotic systems responded to C2H2 by an immediate plateau range in ARA. The Plateau in ARA was in some cases followed by a decline of less extent than reported for many legumes. A concurrent decline in net respiration of the root system was on average 8% of the CO2 efflux prior to C2H2 introduction. Respiration of the root systems in both symbioses responded to elevated oxygen levels in the 10 kPa C2H2 atmosphere by an increase of up to 17% of the net respiration prior to C2H2 introduction in 21 kPa O2. In contrast, the elevated oxygen levels resulted in an immediate drop in ARA followed by a minor increase to a stable level lower than that at the preceding, lower oxygen tension. The symbiosis with the local Frankia had lost all ARA when the partial pressure of O2 exceeded 50 kPa, whereas the symbiosis with Avcll still had some activity at 80 kPa O2. This difference in tolerance of elevated O2 clearly shows that the oxygen exclusion mechanisms may be controlled by the microsymbiont in Alnus-Frankia symbioses. The symbiotic systems recovered ARA to a similar extent when returned from elevated O2 levels to 21 kPa O2.

Growth and Nodulation of Provenances of Casuarina cunninghamiana Inoculated With a Range of Frankia Sources

Abstract: Seed and root nodules (for use as a Frankia inoculum) collected from 18 provenances of Casuarina cunninghamiana Miq. were used in a complete cross-inoculation experiment conducted in a glasshouse. The provenances covered the geographical range of the species and represented major river systems. They were arranged a priori into five groups according to geographical location. Seventeen of the inocula were effective on seed from all provenances; one inoculum failed to nodulate seedlings from any provenance. Inoculum source, seed source and their interaction all affected plant growth. Greatest shoot weight was obtained with seed and inoculum combinations from similar geographical regions, particularly northern inocula with northern seed sources and southern inocula with southern seed sources. When averaged over all seed sources northern inocula were the most generally effective in promoting plant growth. In contrast, when averaged over all inoculum sources, southern seed sources grew best. These results demonstrate the potential for improving the effectiveness of the C. cunninghamiana-Frankia association in forestry by selection of the symbiotic partners.

In vitro propagation and subsequent nodulation of the actinorhizal Hippophae rhamnoides L.

Abstract: Micropropagation of the actinorhizal plant Hippophae rhamnoides L. (sea-buckthorn) was achieved on Murashige and Skoog (MS) medium supplemented with 1 μM of benzylaminopurine (BA). A multiplication frequency of three to five shoots per explant was observed after 28 days. Rooting of these shoots was achieved in a medium containing 1/4 strength MS without growth regulators. The rooted plants were transferred to Turface R artificial substrate and inoculated with pure cultures of two Frankia strains. These plantlets subsequently developed nodules which fixed nitrogen.

Creation of novel nitrogen-fixing actinomycetes by protoplast fusion of Frankia with streptomyces.

Abstract: Protoplast fusion was used for the creation of a novel actinomycete capable of fixing atmospheric nitrogen. Protoplasts of Streptomyces griseofuscus, a fast-growing actinomycete, and Frankia, a slow-growing actinomycete which fixes atmospheric nitrogen in culture and in symbiotic association with alders, were allowed to fuse and regenerate on media without supplied nitrogen. Colonies which regenerated acquired the fast-growing characteristic of Streptomyces and the ability to grow on nitrogen-deficient media from Frankia. These colonies resembled Streptomyces in their morphology and fixed atmospheric nitrogen in culture. They contained both the parent Streptomyces DNA sequences and the Frankia DNA sequences homologous to nif structural genes HDK of K. pneumoniae. In addition to in vitro nitrogen-fixing capacity, one out of 20 colonies also formed nitrogen-fixing root nodules on Alnus rubra, the host plant for the Frankia strain. Examination of the root nodules induced by the hybrids showed only the presence of hyphae-like structures. The typical vesicle-like structures present in Frankia were absent.

Détermination de l'identité isotopique de l'azote fixé par le Frankia associé au genre Alnus

Abstract: To use the 15N natural abundance method to evaluate the symbiotic nitrogen fixation by actinorhizal trees, it is necessary to determine the isotopic identity of assimilated nitrogen from two sources: the soil and the air. This study reports an isotopic value of fixed nitrogen by two alder species (Alnus incana (L.) Moench and Alnus glutinosa (L.) Gaertn. growing on nitrogen-free medium in greenhouse experiments. The δ15N value of the aerial parts was −2. This value was stable with time and did not depend on the Frankia strains used. This value could be used to estimate the nitrogen fixation in the natural ecosystem. Other parameters such as the mobilization of nitrogen reserves and the choice of the reference plant must be investigated to apply this method. The nodules of these two alder species were enriched in 15N relative to the rest of the plant but there was no relationship between symbiotic effectiveness of Frankia strains and 15N enrichment of nodules. On the other hand, for naturally growing trees...

Compatibility of Frankiae spore positive and spore negative inocula with Alnus glutinosa and Alnus incana

Abstract: Growth, nodulation, and nitrogen fixation by Alnus glutinosa (L.) Gaertn. and Alnus incana (L.) Moench inoculated with two Frankia inocula (a spore positive nodule homogenate and a spore negative isolate) were examined. The spore positive inoculum had a very low compatibility with A. glutinosa while a very large compatibility was found with the spore negative strain. Alnus incana had little specificity to the two types of Frankia which allowed the coexistence and the expression of the nitrogen fixation capacity of the two nodule types on the same root system. This result suggests that, despite the competition from indigenous strains, it may be possible to introduce in some areas a highly effective Frankia strain after careful study of the compatibility.

The genus Frankia: actinomycete symbionts of plants.

Abstract: Biological N2 fixation is performed most effectively by prokaryotic diazotrophs when in mutualistic symbioses with higher plants. The most intensively studied N2-fixing symbioses involve leguminous plants and rhizobia. However, Frankia actinomycetes have attracted attention recently because they form root nodules on a broad range of non-legumes and because such nodules fix N2 as effectively as rhizobial nodules. Since the Frankia symbiosis results from an actinomycetic invasion of plant roots, it has been termed the 'actinorhizal symbiosis'.

Nitrogenase activity decay and energy supply in Frankia after addition of ammonium to the host plant Alnus incana

Abstract: A clone of Alnus incana (L.) Moench was grown in symbiosis with a local source of Frankia or with Frankia Ar14. Seven to 9-week-old plants were given 20 mM NH4Cl (20 mM KCl = control) for 3 days. Nitrogenase activity of intact plants decreased gradually within the 3 days of treatment to about 10% of the initial rates. Hydrogen evolution in air and total nitrogenase activity responded similarly to the treatment. Relative efficiency of nitrogenase thus remained the same throughout the study period. Control plants were not affected. Measurements of nitrogenase activity in root nodule homogenates (in vitro measurements) indicated loss of active nitrogenase rather than shortage of energy for nitrogenase activity in Frankia from ammonium-treated plants. Shoots were exposed to 14CO2 and translocation of 14C to Frankia vesicle clusters prepared from root nodules was studied. Frankia vesicle clusters from ammonium-treated plants contained about half as much 14C as those of control plants during all 3 days studied. One explanation for the observed effects is that a reduced supply of carbon to Frankia vesicles in the root nodules caused a reduced metabolic rate, including reduced protein synthesis and synthesis of nitrogenase.

Nitrogenase activity, hydrogen evolution and biomass production in different Casuarina symbioses

Abstract: Nitrogenase activity, hydrogen evolution, biomass production and nodulation were studied in threeCasuarina species,C equisetifolia Forst,C glauca Sieber ex Spreng andC obesa Miq, either inoculated with a crushed nodule inoculum prepared fromC glauca nodules or inoculated with the pure cultureHFP CcI3 Nodulation was also studied inC cristata Miq inoculated with the above mentionedFrankia sources

Isolation of frankia strains from root nodules of myrica rubra

Abstract: Frankia strains were successfully isolated from Myrica rubra root nodules using a double-layer agar system consisting of an upper layer of 1% agar which included the endophytes and a lower layer of 1.5% agar which contained the nutrients. Colonies appeared within 1 month and their diameter increased from 0.5 to 1.0 mm 2 months after the inoculation. Hyphae, sporangia, and vesicles were observed in the colonies. The Frankia isolates grew well in liquid media supplemented with vitamins including biotin and p-aminobenzoic acid (modified Qmod medium; see Lalonde and Calvert 1979). The Frankia isolates grown in N-deficient modified Qmod medium exhibited an acetylene reducing activity. Nodules were formed on the roots of Myrica rubra by inoculation of the Frankia isolates and the acetylene reducing activity of the nodules amounted to 16 /anol C2H4·(g fr wt)-1·hr-1. No nodules were formed on Coriaria japonica after the inoculation of the isolates. These results suggest that the Frankia strains isolated ...

Cellular Interactions between Host and Endosymbiont in Dinitrogen-Fixing Root Nodules of Woody Plants

Abstract: During the last decade increasing attention has been paid by plant scientists to temperate and tropical woody plants known to establish symbiotic relationships with soil microorganisms capable of generating and expressing the enzyme nitrogenase. In the appropriate biological context this enzyme catalyzes the reduction of molecular dinitrogen from the atmosphere into organic form assimilable by the eukaryotic partner in the association. Management of biological nitrogen fixation by tree species is viewed increasingly as an important approach to improvement of world agriculture and forestry.

Competitiveness of Frankia strains on Elaeagnus clonal plantlets

Abstract: Actinorhizae were synthetized on in vitro propagated Elaeagnus angustifolia L. clonal plantlets, by inoculation with combinations of pure cultures of three effective Frankia strains and an ineffective one. Using the OsO4 isolation method, 774 nodule fragments from 79 plantlets were treated and 152 Frankia reisolates were obtained. The soluble protein patterns of 121 reisolates were analyzed by one-dimensional SDS-PAGE, which permitted their positive identification. The protein patterns of all reisolates obtained from plants inoculated with a single strain were indistinguishable from those of the original strain. In six different dual strain inoculations, only one of the two Frankia strains could be reisolated. Thus, some Frankia strains appeared to be more competitive than others toward the Elaeagnus root system.

Effect of a Clay Mineral (Montmorillonite) on the Nodulation of Alnus and on the Nitrogenase Activity of Frankia in Pure Culture

Abstract: L'addition de montmorillonite a des semis d'aulne, inocules avec la lignee Ai1 de Frankia et cultives dans du gravier, conduit a un doublement du nombre de nodosites. Il semble que l'effet stimulant de l'argile soit du partiellement a l'adsorption de composes inhibiteurs secretes par l'aulne. La montmorillonite affecte l'activite de la nitrogenase de Frankia Ai1 en culture pure en reduisant la phase de latence. Des observations au microscope optique et electronique montrent des interactions entre Frankia et l'argile

Effective nodulation ofCoriaria myrtifolia L. induced byFrankia strains fromAlnus glutinosa L. (Gaertn.)

Abstract: The present contribution covers the cross-inoculation between two actinorhizae belonging to different genera and families, mainlyAlnus glutinosa andCoriaria myrtifolia. Frankia strains isolated fromA. glutinosa received from the Netherlands (LDAgp1r1, LDAgn1) and from Scotland (UGL010708), induced a fully effective nodulation onC. myrtifolia. The same effect was caused by a nodule extract fromA. glutinosa. The reverse, a crushed-nodule inoculum fromC. myrtifolia nodulated all theA. glutinosa seedlings, though nodules formed were less effective than those induced by the other inocula. Re-isolation of thoseFrankia strains from the nodules formed onA. glutinosa was readily obtained, whereas attempts to re-isolate them from the nodules formed onC. myrtifolia failed, suggesting that isolation procedures different to those employed should be tried.