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1.
Summary Measurements of auxin and cytokinin activities in extracts of Casuarina root nodules were made. The nodules were induced either by pure culture of Frankia strain CgI4 or by crushed nodule inoculum. Levels of cytokinin activity were significantly higher in root nodules induced by pure Frankia culture than in those induced by crushed nodule inoculum. However, the reasons for this are unknown. Seasonal variation in levels of cytokinin activity in Casuarina nodules has also been detected.Dedicated to the memory of Professor John G. Torrey 相似文献
2.
Summary Seedlings of Casuarina spp. and Allocasuarina spp. were grown from seed in the greenhouse and inoculated with a nodule suspension from C. equisetifolia. Plants of Casuarina spp. nodulated regularly and were effective in nitrogen-fixation. Only one species of Allocasuariona, A. lehmanniana formed root nodules. Using these plants as source of inoculum, the isolation of a new Frankia sp. HFPA11I1 (HFP022 801) was made and the strain was grown in pure culture. Frankia sp. HFPA11I1 grows well in a defined medium and shows typical morphological characteristics. In media lacking combined nitrogen, the filamentours bacterium forms terminal vesicles in abundance and differentiaties large intrahyphal or terminal sporangia containing numerous spores. This strain, used as inoculum, nodulates effectively seedlings of C. equisietifolia and C. cunninghamiana, forming nodules with verically-growing nodule roots. Although effective in acetylene reduction, the endophyte within the nodules is filamentous and lacks veiscles. When used to inoculated seedlings of A llocasuarina lehmanniana, Frankia sp. HFPA11I1 induces root nodules which are coralloid and lacking nodule roots. The nodules are effective in acetylene reduction and the filamentous hyphae of Frankia within the nodule lobes lack vesicles. Effective nodulation in A. Lehmanniana depends upon environmental conditions of the seedlings and proceeds much more slowly than in Casuariana. 相似文献
3.
Isoflavonoid (+)-pisatin, the main phytoalexin of pea ( Pisum sativum), was tested for its inducer and suppressor activity in respect of the nodABCIJ operon of Rhizobium leguminosarum bv. viciœ, a pea symbiont, in the presence of a flavonoid receptor-coding gene nodD of this biovar. No nod gene-inducing activity of pisatin could be detected up to 100 μmol/L concentration. The suppressor activity as determined
against 0.1 μmol/L naringenin was expressed only above 10 μmol/L pisatin, i.e. at a concentration higher by a one order of magnitude, than with the potent flavonoid suppressor rhamnetin and by two orders
above the isoflavonoid, suppressor daidzein. Analogously, only a weak suppression was observed with NodD1 of R. meliloti, the alfalfa symbiont. The results do not support the notion about the role of plant defence substances in the control of
rhizobial symbiosis. 相似文献
4.
Plant needles of Casuarina equisetifolia were collected and analyzed in parallel with soil analysis. In three strains of Frankia—symbionts of Casuarina—their infectivity and plant performance was determined in vitro after soil amendment with different leaf litter concentrations. Only one strain was able to nodulate the plant at all litter
concentrations (0.5, 3 and 5%) although the nodules were very small. However, all treated plants grew poorly; their growth
was reduced by approximately 90% (for 5% litter concentration) compared to plants grown on untreated soil, on the basis of
total dry mass. Inhibition of nodulation can be attributed to high concentrations of some elements and compounds that were
either found in C. equisetifolia litter or originally found in soil ( i.e. chloride, cyanide, copper, manganese and phenols). In general, plant growth decreased as more litter was added. Plant total
nitrogen content was also reduced after increasing the litter concentration. The inhibitory effect of high litter concentrations
was mainly on plant growth and to a lesser extent on plant nodulation by Frankia strains. 相似文献
5.
The genotoxic effect of chloroquine (CQ), a 4-aminoquinoline antimalarial drug was investigated in rat liver cells using the
alkaline comet assay. Chloroquine (0–1000 μmol/L) significantly increased DNA strand breaks of rat liver cells dose-dependently.
Rat liver cells exposed to CQ (100–500 μmol/L) and treated with endonuclease III and formamidopyrimidine-DNA glycosylase,
the bacterial DNA repair enzymes that recognize oxidized pyrimidine and purine, respectively, showed greater DNA damage than
those not treated with the enzymes, providing evidence that CQ induced oxidation of purines and pyrimidines. Treatment of
cells with 5 mmol/L N-acetylcysteine, an intracellular reactive oxygen species (ROS) scavenger, and 100 μmol/L and 250 μmol/L deferoxamine, an
established iron chelator, significantly decreased the CQ-induced strand breaks and base oxidation, respectively. Similarly,
the formation of DNA strand breaks and oxidized bases was prevented by vitamin C (10 μmol/L) (a water-soluble antioxidant),
quercetin (50 μmol/L) (an antioxidant flavonoid), and kolaviron (30 μmol/L and 90 μmol/L) (an antioxidant and a liver hepatoprotective
phytochemical). The results indicate that the genotoxicity of CQ in rat liver cells might involve ROS and that free radical
scavengers may elicit protective effects in these cells. 相似文献
6.
Nickel is a toxic and carcinogenic environmental and occupational pollutant and quercetin is a dietary flavonoid that is reported
to modulate effects of many mutagens and carcinogens. We investigated the ability of nickel chloride to induce DNA damage
in human colonic mucosa cells in the presence of quercetin, using the alkaline comet assay. Nickel chloride (5–250 μmol/L)
evoked dose-dependent DNA damage and quercetin at 50 μmol/L decreased the extent of this damage. The cells exposed to nickel
chloride progressively removed their DNA damage and the presence of 50 μmol/L quercetin in the repair-incubation medium did
not affect the repair kinetics. Cells exposed to nickel and treated with endonuclease III, an enzyme recognizing oxidized
bases, displayed a greater extent of DNA damage than those not treated with the enzyme. Quercetin did not exert a significant
effect on the production of oxidized bases by nickel. Pretreatment of the cells with a nitrone spin trap, N- tert-butyl-α-phenylnitrone, decreased the extent of DNA damage evoked by nickel. Quercetin caused a further decrease in the extent
of the damage in the presence of the trap. The results obtained suggest that reactive oxygen species, including free radicals,
might be involved in the formation of DNA lesions induced by nickel chloride in colonic mucosa cells and that quercetin may
exert protective effects in these cells.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
7.
Strains of M. ciceri, symbionts of chickpea ( Cicer arietinum) were incubated with the flavonoids naringenin, daidzein and quercetin which have earlier been reported as inducers and inhibitors
of nodABC-lacZ fusion of M. ciceri. Preincubation of M. ciceri with naringenin and daidzein (100 nmol/L) for 1 d improved the competitive ability of the inoculated strain while preincubation
with quercetin decreased the nodule occupancy of inoculated strain under sterile conditions. Under nonsterile conditions induced
strains of Rcd 301 and HT-6 formed by 23 and 18% more nodules, respectively, than untreated control. Quercetin-treated strains
showed by 13–20% fewer nodules than untreated controls. Therefore, it is possible to regulate the competitive ability of inoculated
strains by flavonoid treatment. 相似文献
8.
Summary A Frankia strain (ORS 021001) isolated from Casuarina junghuhniana root nodules was shown to produce four type of structures in vitro: vegetative hyphae, sporangiospores within sporangia, N 2-fixing vesicles, and a fourth type of structure which is described in detail in this report. Structures of this latter type which we propose to call reproductive torulose hyphae: (RTH) result from enlargement and multiple segmentation of vegetative hyphae into torulose chaions of spore-like cells. RTH differ from sporangia in three major aspects: morphology, morphogenesis and outgrowth. RTH play an important role in survival and reproduction of Frankia strain ORS 021001. Adding activated charcoal to the nutrient medium promotes the formation of Frankia colonies orginating from RTH. 相似文献
9.
A strain of Frankia was isolated from Gymnostoma papuanum(Casuarinaceae) nodules harvested from rooted cuttings which had been inoculated with a suspension of crushed Casuarina equisetifolia nodules. Designated HFPGpI1 (catalogue #HFP021801), this strain is pigmented and similar to other pigmented Frankia strains in cultural characteristics. A previously unknown spiraled hyphal morphology was observed at very low frequency in some cultures of this strain. HFPGpI1 is infective and effective on G. papuanum but not on any Casuarina species tested. It also infects members of the family Elaeagnaceae and Myrica gale. The host plant G. papuanum can be infected with a wide range of Frankia isolates and thus can be considered a promiscuous host, unlike its close relatives in the genera Casuarina and Allocasuarina which are very restrictive as to which strains may nodulate them. 相似文献
10.
The efficiency of different Finnish Frankia strains as symbionts on Alnus incana (L.) Moench was evaluated in inoculation experiments by measuring nitrogen fixation and biomass production. Since all available
pure cultures of Frankia are of the Sp − type (sporangia not formed in nodules), but the dominant nodule endophyte of A. incana in Finland is of the Sp + type (sporangia formed in nodules), crushed nodules of this Frankia type were included.
The Sp − pure cultures, whether originating from A. incana or A. glutinosa, produced with one exception, similar biomass with A. incana. The highest biomass was produced with an American reference strain from A. viridis crispa. Using Sp + nodule homogenates from A. incana as inoculum, the biomass production was only one third of that produced by Sp − pure cultures from the same host.
Hence, through selection of the endophyte it is possible to exert a considerable influence on the productivity of Alnus incana. 相似文献
11.
Summary Fifteen species from three genera of the Casuarinaceae were inoculated with suspensions of Frankia prepared from single nodule-lobes collected from different species and genera within the Casuarinaceae. Host-endophyte specificity
was expressed mainly at the generic level. There was marked cross-inoculation within Casuarina and little nodulation of Casuarina species from Allocasuarina sources with the exception of 3 sources of Frankia from A. torulosa which showed a high tendency to nodulate Casuarina species. Few sources from Casuarina nodulated species of Allocasuarina and while cross-inoculation within Allocasuarina was
frequent it was less marked than within Casuarina. Some Frankia inocula had wider host ranges than others, nodulating outside the genus or series of origin. It was not possible to determine
if these apparent wider ranges in host spectra reflected genotypic differences between Frankia or were associated with the presence of more than one Frankia strain in some inocula. 相似文献
12.
Summary The isolations of three new strains of Frankia were made from root nodules of Casuarina cunninghamiana growing aeroponically. Two strains, HFPCCI1 and HFPCcI2 isolated by Lopez are typical Frankia strains, producing sporangia among filamentous mats in culture and, in the absence of combined nitrogen, forming vesicles and showing acetylene reduction. They are red-pigmented and, although failing to nodulate Casuarina hosts, effectively nodulated Elaeagnus and Hippophae. A third strain HFPCcI3 isolated by Zhang from the same source, also a typical Frankia, can form sporangia and vesicles in culture and reduce acetylene, is unpigmented, fails to nodulate Elaeagnus but effectively nodulates C. cunninghamiana and C. equisetifolia. Comparisons are made among all of the Casuarina isolates in our collection from around the world (twelve in all) with regard to their cultural characteristics and capacity to infect host plant species. Questions are raised about the specificity of the various isolates and their possible affinities. Opportunities are suggested for inoculation of seedlings for forestry and field application using the infective, effective strains now available. 相似文献
13.
Frankia isolates from nodules of the genera Casuarina (BR, S21, Thr), Allocasuarina (Allo2), and Gymnostoma (G80) were found to grow exponentially with high biomass yield and minimal sporangia formation in stirred propionate mineral
medium when supplemented either with 2.4 μM palmitic acid (C16:0), pentadecanoic (C15:0), heptadecanoic (C17:0), or linoleic
(C18:2, cis 9, 12) fatty acids. Strains also grew with lauric (C12:0) or myristic (C14:0) acids, but gave lower biomass yield. Stearic
acid (C18:0) produced a good biomass yield, but cultures slowly accumulated sporangia; oleic acid (C18:1, cis-9) was detrimental to growth. Caprylic (C8:0) or capric (C10:0) acids proved to be prejudicial for long-term storage of Frankia strains. In experiments using labeled 1,2-dipalmitoyl phosphatidylcholine and palmitic acid, radioactivity bound rapidly
to the insoluble, but solvent-extractable fraction of Frankia cells. In contrast, label from propionic acid accumulated in the cytosolic fraction. Therefore, the beneficial effect of
some specific phospatidylcholines or free fatty acids on Frankia growth appears to result from their utilization as building blocks for the membrane, suggesting that membrane biosynthesis
may be the limiting step for Frankia growth in unamended propionate mineral medium.
Received: 9 October 1995 / Accepted: 24 February 1996 相似文献
14.
Summary This is an ultrastructural study of development of infected cells in nitrogen fixing root nodules of Casuarina spp. While several aspects of development are similar to those found in many other actinorhizae, unusual aspects of development of the host cell and differentiation of the endophyte in Casuarina are correlated with unusual changes in the wall of the infected cell. Instead of vesicles the endophyte forms atypical hyphae in mature infected cells. These unusual hyphal forms are termed intracellular hyphae. Intracellular hyphae are nonseptate hyphae which originate and terminate within the same host cell, and have a varying diameter and a multidirectional growth and branching pattern. A laminate surface layer previously undescribed on hyphae of Frankia is a feature common to most Casuarina endophytic hyphae and is probably similar chemically to the laminae comprising the multilamellate envelope of endophytic vesicles in other actinorhizae.This paper is Florida Agricultural Experiment Station Journal Series No. 7350. 相似文献
15.
Factors affecting the establishment of Alnus/ Frankia symbioses were studied partly by following the survival of Frankia strains exposed to different soil conditions, and partly by investigating the effect of pH on nodulation. Two Frankia 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 from Alnus 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.
The strains were introduced into two Frankia-free soils, peat and fine sand. Their survival, measured as the persistance of nodulation capacity using the plant infection
technique, was followed for 14 months. The survival curves of the strains were similar despite the morphological differences
between the strains in pure culture. The nodulation capacities declined over time both at 14 and 22°C. Survival was better
in soils limed to a pH above 6 than in soils at their original pH (peat 2.9, fine sand 4.2).
The effect of pH on nodule formation in Alnus seedlings by the Frankia strains was studied in liquid culture. The number of nodules increased linearly within the pH range studied (3.5–5.8). No
nodules were formed at pH 3.5. 相似文献
16.
Four Frankia-Casuarina endosymbiont strains were tested for their infectivity and effectiveness on C. equisetifolia plants after 1 d, 3 and 6 months of Frankia storage at 7, 28 and 40°C as liquid-cultures and polyacrylamide gel (PAG)-immobilized inocula. At lower temperature the number
of nodules was the same or higher than control for liquid inocula except after 6 months of storage. For the PAG-entrapped Frankia lower numbers of nodules were recorded due to the use of high Frankia titers. In general, the results showed comparable plant dry mass, total nitrogen, root to shoot and nodules to plant ratios
at lower temperature treatments. Increasing time and temperature was accompanied with reduced infectivity and effectiveness
on inoculated plants. No nodulation was scored on plants inoculated with liquid and PAG-entrapped inocula stored at 40°C for
6 months; subsequently, plant growth was inhibited. The variations in results obtained for different strains and treatments
lead to variations in plant nitrogen-fixing ability. The use of PAG as a carrier for different Frankia strains is suggested; the recommended storage temperature for PAG-immobilized Frankia is 7–28°C for up to 3 months. 相似文献
17.
Astrocyte and microglia cells play an important role in the central nervous system (CNS). They react to various external aggressions
by becoming reactive and releasing neurotrophic and/or neurotoxic factors. Rutin is a flavonoid found in many plants and has
been shown to have some biological activities, but its direct effects on cells of the CNS have not been well studied. To investigate
its potential effects on CNS glial cells, we used both astrocyte primary cultures and astrocyte/microglia mixed primary cell
cultures derived from newborn rat cortical brain. The cultures were treated for 24 h with rutin (50 or 100 μmol/L) or vehicle
(0.5% dimethyl sulfoxide). Mitochondrial function on glial cells was not evidenced by the MTT test. However, an increased
lactate dehydrogenase activity was detected in the culture medium of both culture systems when treated with 100 μmol/L rutin,
suggesting loss of cell membrane integrity. Astrocytes exposed to 50 μmol/L rutin became reactive as revealed by glial fibrillary
acidic protein (GFAP) overexpression and showed a star-like phenotype revealed by Rosenfeld’s staining. The number of activated
microglia expressing OX-42 increased in the presence of rutin. A significant increase of nitric oxide (NO) was observed only
in mixed cultures exposed to 100 μmol/L rutin. Enhanced TNFα release was observed in astrocyte primary cultures treated with
100 μmol/L rutin and in mixed primary cultures treated with 50 and 100 μmol/L, suggesting different sensitivity of both activated
cell types. These results demonstrated that rutin affects astrocytes and microglial cells in culture and has the capacity
to induce NO and TNFα production in these cells. Hence, the impact of these effects on neurons in vitro and in vivo needs to be studied. 相似文献
18.
From homogenates prepared from surface-sterilized nodules ofseedlings of Casuarina cunninghamiana grown aeroponically, astrain of Frankia designated HFPCc13 was isolated and has beengrown in pure filamentous culture in a defined synthetic nutrientmedium. Vesicle and sporangium formation can be induced by removalof combined nitrogen from the medium. Frankia strain HFPCc13nodulates young seedlings of C. cunninghamiana and C. equisetifoliawithin three weeks of inoculation with an optimum root mediumpH of 67 for nodulation and optimum temperature of 3035 °C. The presence of combined nitrogen in the root mediuminhibits nodulation with NH 4+ more inhibitory than NO 3. Frankia HFPCc13 does not nodulate Allocasuarina species withinthe same family nor several other possible actinorhizal plantstested. Thus this strain is quite precise in its host specificity.The rate of acetylene reduction was greater in C. cunninghamianathan the closely related species C. equisetifolia. In neitherof these host species were vesicles observed to occur withinthe infected root nodules which had been demonstrated to beactively fixing dinitrogen. Root nodules were shown to be activein acetylene reduction over a range of O 2 concentration in thegaseous environment with an optimum at about 20 per cent O 2,the ambient P O2 of the air. The mechanism(s) for oxygen protectionof nitrogenase within the filamentous form of Frankia withinthese nodules remains to be explained. Casuarina, Frankia, nodulation, nitrogen fixation 相似文献
19.
The effects of soil type (an acid peat and 2 acid brown earths) and Frankia source (3 spore-positive crushed nodule inocula and spore-negative crushed nodules containing the single Frankia ArI5) on nodulation, N content and growth of Alnus glutinosa and A. 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 with A. glutinosa superior to A. rubra. The former species was also superior to A. 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 containing Frankia ArI5 only gave poor infection of the host plant, suggesting that inoculation with locally-collected crushed nodules can be a preferred alternative to inoculation with Frankia isolates of untested effectivity. Evidence of adaptation of Frankia 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 of Frankia on peat may be improved by strain selection. 相似文献
20.
Nodule samples were collected from four alder species:Alnus nepalensis, A. sibirica, A. tinctoria andA. mandshurica growing in different environments on Gaoligong Mountains, Yunnan Province of Southwest China and on Changbai Mountains, Jilin Province of Northeast China. PCR-RFLP analysis of the IGS betweennifD andnifK genes was directly applied to unculturedFrankia strains in the nodules. A total of 21 restriction patterns were obtained. TheFrankia population in the nodules ofA. nepalensis had the highest genetic diversity among all fourFrankia populations; by contrast, the population in the nodules ofA. mandshurica had the lowest degree of divergence; the ones in the nodules ofA. sibirica andA. tinctoria were intermediate. A dendrogram, which was constructed based on the genetic distance between the restriction patterns, indicated thatFrankia strains fromA. sibirica andA. tinctoria had a close genetic relationship.Frankia strains fromA. nepalensis might be the ancestor ofFrankia strains infecting otherAlnus species. From these results and the inference of the ages ofAlnus host species, it is deduced that there was a co-evolution betweenAlnus and its microsymbiontFrankia in China. 相似文献
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