Effect of oxygen on substrate utilization for nitrogen fixation and growth in Frankia spp.

Lopez, Mary F.; Murry, Marcia A.; Torrey, John G.

doi:10.1007/bf00443647

Cited by 3 publications

(1 citation statement)

References 27 publications

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“…The presence of a physical barrier to Og is concluded from the kinetics of respiration and ARA in cultured Frankia (Murry, Fontaine & Tjepkema, 1984;Murry et al, 1985;Lopez et al, 1986a). In nodules of Alnus incana, nitrogenase activity (Hgevolution or ARA) was decreased at O^ tensions below and above ambient, indicating that the Og diffusion barrier was fixed in this symbiosis (Rosendahl & Huss-Danell, 1988;Huss-Danell & Lundquist, 1993).…”

Section: The Oxygen Problemmentioning

confidence: 99%

Actinorhizal symbioses and their N₂ fixation

1997

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summary More than 200 angiosperms, distributed in 25 genera, develop root nodule symbioses (actinorhizas) with soil bacteria of the actinomycetous genus Frankia. Although most soils studied contain infective Frankia, cultured strains are available only after isolation from root nodules. Frankia infects roots via root hairs in some hosts or via intercellular penetration in others. The nodule originates in the pericycle. The number of nodules in Alnus is determined by the plant in an autoregulated process that, in turn, is modulated by nutrients such as nitrogen and phosphate. Except in the genera Allocausarina and Casuarina, Frankia in nodules develops so‐called vesicles where nitrogenase is localized. Sporulation of Frankia occurs in some symbioses. As a group, actinorhizal plants show a large range of anatomical and biochemical adaptations in order to balance the oxygen tension near nitrogenase. In symbioses with well aerated nodule tissue like Alnus, the vesicles have a multilayered envelope composed mainly of lipids, bacterio‐hopanetetrol and their derivatives. This envelope is assumed to retard the diffusion of oxygen into the nitrogenase‐containing vesicle. In symbioses like Casuarina, the infected plant cells themselves, rather than Frankia, appear to retard oxygen diffusion, and high concentrations of haemoglobin indicate an infected region with a low oxygen tension. At least in Alnus spp., ammonia resulting from N2 fixation is assimilated by glutamine synthetase in the plant. The carbon compound(s) used by Frankia in nodules is not yet known. Nitrogenase activity decreases in response to a number of environmental factors but recovers upon return to normal conditions. This dynamism in nitrogenase activity is often explained by loss and recovery of active nitrogenase and has been traced to loss and recovery of the nitrogenase proteins themselves. Recovery is partly due to growth of Frankia and to development of new vesicles in the Alnus nodules. In the field, varying conditions continuously affect the plants and the measured rate of N2 fixation is a result not only of the conditions prevailing at the moment but also of the conditions experienced over preceding days. N2 fixed by actinorhizal plants is substantial and actinorhizal plants have great potential in soil reclamation and in various types of forestry. Several species are also useful in horticulture.

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Section: The Oxygen Problemmentioning

confidence: 99%

Actinorhizal symbioses and their N₂ fixation

1997

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Oxygen Regulation and Hemoglobin

Silvester

Harris

Tjepkema

1990

The Biology of Frankia and Actinorhizal Plants

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Effect of O₂ on vesicle formation, acetylene reduction, and O₂-uptake kinetics in Frankia sp. HFPCcI3 isolated from Casuarina cunninghamiana

Murry¹,

Zhang²,

Torrey³

1985

Can. J. Microbiol.

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The effect of the partial pressure of oxygen (PO2) on the formation of vesicles, which are thought to be the site of N2 fixation in Frankia, was studied in HFPCcI3, an effective isolate from Casuarina cunninghamiana. Unlike other actinorhizal root nodules, vesicles are not produced by the endophyte in Casuarina nodules. However, in culture under aerobic conditions, large, phase-bright vesicles are formed in HFPCcI3 within 20 h following removal of NH+4 from the culture medium and reach peak numbers within 72 to 96 h. In vivo acetylene reduction activity parallels vesicle formation. Optimum rates of acetylene reduction in short-term assays occurred at 20% O2 (0.2 atm (1 atm = 101.325 kPa] in the gas phase. O2 uptake (respiration) determined polarographically showed diffusion-limited kinetics and remained unsaturated by O2 until 300 microM O2. In contrast, respiration in NH+4-grown cells was saturated by O2 between 8 and 10 microM O2. These results indicate the presence of a diffusion barrier associated with the vesicles. Vesicle development was repressed in cells incubated in N-free media sparged with gas mixtures with PO2 between 0.001 and 0.003 atm. Nitrogenase was induced under these conditions, but acetylene reduction was extremely O2 sensitive. The kinetics of O2 uptake as a function of dissolved O2 concentration in avesicular cells were similar to those in NH+4-grown cells indicating the lack of a diffusion barrier. These results demonstrate that vesicle formation and the development of the O2 protection mechanisms of nitrogenase are regulated by ambient PO2 in HFPCcI3.

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Effect of oxygen on substrate utilization for nitrogen fixation and growth in Frankia spp.

Cited by 3 publications

References 27 publications

Actinorhizal symbioses and their N₂ fixation

Actinorhizal symbioses and their N₂ fixation

Oxygen Regulation and Hemoglobin

Effect of O₂ on vesicle formation, acetylene reduction, and O₂-uptake kinetics in Frankia sp. HFPCcI3 isolated from Casuarina cunninghamiana

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Effect of oxygen on substrate utilization for nitrogen fixation and growth in Frankia spp.

Cited by 3 publications

References 27 publications

Actinorhizal symbioses and their N2 fixation

Actinorhizal symbioses and their N2 fixation

Oxygen Regulation and Hemoglobin

Effect of O2 on vesicle formation, acetylene reduction, and O2-uptake kinetics in Frankia sp. HFPCcI3 isolated from Casuarina cunninghamiana

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Product

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Actinorhizal symbioses and their N₂ fixation

Actinorhizal symbioses and their N₂ fixation

Effect of O₂ on vesicle formation, acetylene reduction, and O₂-uptake kinetics in Frankia sp. HFPCcI3 isolated from Casuarina cunninghamiana