Potential for Nitrogen Fixation in Maize Genotypes in Brazil

Bülow, Joachim F. W. Von; Döbereiner, Johanna

doi:10.1073/pnas.72.6.2389

Cited by 260 publications

(61 citation statements)

References 6 publications

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“…No pigment has been observed. Thus, although they are somewhat similar to the maize and Digitaria isolates, they differ in these properties and in the difficulty in isolating them by the method described by von Bulow & Dobereiner (1975) and Day & Dobereiner (1976). The nitrogen-fixing spirilla described by Becking (1963) did not grow in the absence of yeast extract and may have been the same as the isolates described here.…”

Section: R E S U L T S a N D Discussionmentioning

confidence: 72%

“…This activity is attributed to asymbiotic bacteria. Microaerophilic acetylene-reducing spirilla have been isolated from the roots of maize (von Bulow & Dobereiner, 1975) and Digitaria decumbens (Day & Dobereiner, 1976) plants in Brazil; these roots also showed high levels of nitrogenase activity by the acetylene-reduction method. The root zone of some aquatic macrophytes is known to be aerated via a channel of tissue (aerenchyma) through which air passes from the shoots to the roots (Armstrong, 1972).…”

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confidence: 99%

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Isolation of Acetylene-reducing Spirilla from the Roots of Potamogeton filiformis from Loch Leven (Kinross)

Sylvester-Bradley¹

1976

Journal of General Microbiology

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I N T R O D U C T I O NSignificant levels of nitrogen-fixation, measured using 15N2, and/or acetylene reduction (Hardy et al., 1968), occur on the roots of non-leguminous aquatic macrophytes (Patriquin & Knowles, 1972;Bristow, 1974), and on the roots of rice seedlings growing in waterlogged soil (Dommergues et al., 1973). This activity is attributed to asymbiotic bacteria. Microaerophilic acetylene-reducing spirilla have been isolated from the roots of maize (von Bulow & Dobereiner, 1975) and Digitaria decumbens (Day & Dobereiner, 1976) plants in Brazil; these roots also showed high levels of nitrogenase activity by the acetylene-reduction method. The root zone of some aquatic macrophytes is known to be aerated via a channel of tissue (aerenchyma) through which air passes from the shoots to the roots (Armstrong, 1972). This enables the plants to grow in anaerobic sediment. The aerobic or semi-aerobic zone immediately around the roots is likely to be suitable for microaerophilic bacteria. In this study the roots of Potamogeton Jiliformis, one of the major aquatic macrophytes in Loch Leven, Kinross, Scotland (Jupp, Spence & Britton, 1974), were examined for the presence of nitrogen-fixing spirilla, and some characteristics of pure cultures of the organisms isolated from them were investigated. M E T H O D SBasic medium. This contained: 0.4 g KH,PO,; 0.1 g K,HPO,; 0.2 g MgSO,. 7H,O; 0 -1 g NaCl; 0-02 g CaCl,; 0.01 g FeCI,; 0.002 g NaMoO,.zH,O; 3.5 g (semi-solid) or 15 g (pour plates) Difco Bacto Special Noble Agar; I 1 distilled water. The carbon and nitrogen sources added to this medium in different experiments are described below. All incubations were at 30 "C.Preliminary enrichment cultures. Samples of P. $Ziformis roots (0.5 to 1.0 cm long) were taken and, on the same day, were washed in lake water and placed in semi-solid medium (I cm deep in I oz vials) containing 0.5 % sodium malate. After incubation for I day, the root pieces were removed and acetylene-reduction tests were carried out on the cultures.Purification. Purification of acetylene-reducing cultures as described by von Bulow & Dobereiner (I 975) was not successful. Purification was achieved by mixing samples from preliminary enrichment cultures which reduced the most acetylene with 5 ml sterile distilled water or buffered saline (pH 7.0) for 5 min; and then inoculating 0.1 ml samples into pour plates containing 0.5 % sodium malate and 0.05 % yeast extract, and incubating for 7 days.

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Section: R E S U L T S a N D Discussionmentioning

confidence: 72%

mentioning

confidence: 99%

Isolation of Acetylene-reducing Spirilla from the Roots of Potamogeton filiformis from Loch Leven (Kinross)

Sylvester-Bradley¹

1976

Journal of General Microbiology

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“…4, inset) Azospirillum spp. has been proposed as one of the major N2-fixing organisms responsible for the nitrogenase activity associated with corn and other grasses grown under tropical conditions (5,8,12), but it would still be premature to propose a similar role for the azospirilla occurring in New Jersey soils.…”

Section: Resultsmentioning

confidence: 99%

“…has been proposed as the major organism responsible for the nitrogenase activity in tropical grasses (5,8,12). On the other hand, Azospirillum spp.…”

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Nitrogenase Activity Associated with Roots and Stems of Field-Grown Corn (Zea mays L.) Plants

De-Polli

Boyer²,

Neyra³

1982

Plant Physiol.

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Collectively, the results provided strong evidence for the occurrence of nitrogenase activity associated with corn plants growing in a temperate climate and dependent upon indigenous N2-fixing bacteria.In corn roots, maximal nitrogenase activity has been reported to be associated with a variety of plant factors: stage of development, plant genotype, low N levels, high temperatures, etc. (1,5,6,13,15).In all of these studies, nitrogenase activity was measured, using excised roots, after prolonged preincubations (12-18 h) at reduced 02 tensions. The limitations of the use of preincubated roots have been discussed in recent reviews (13,19). Bacterial proliferation has been demonstrated to occur during long preincubation times at low 02 and interpreted as an overestimation of the actual nitrogenase activities occurring in situ (3,18). Most important, however, has been the confirmation of nitrogen fixation in grassbacteria associations by 15N2 incorporation into plant parts (7) and the recent report of immediate acetylene reduction by excised grass roots, assayed under air (21).

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Nitrogen Fixation

Newton¹

2000

Kirk-Othmer Encyclopedia of Chemical Technology

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Nitrogen fixation converts inert atmospheric molecular nitrogen gas into reduced forms whereby the nitrogen may be used by all life forms for protein and nucleic acid production. The biological process occurs only in microorganisms and is the principal contributor of fixed nitrogen to the biosphere. Fixed nitrogen is also derived from nonbiological processes, such as fires, volcanoes, and lightning, and from industrial fixation. The Haber‐Bosch ammonia process is highly energy‐intensive but is the most economical industrial process available. Agriculturally, the most important source of biologically fixed nitrogen is the symbiotic system involving leguminous plants which harbor rhizobia bacteria in nodules on their roots. Smaller contributions are made by other, less formal systems and by free‐living microbes. All of the biological systems use a similar metalloenzyme complex, called nitrogenase. Nitrogen fixation research is discussed from a genetic standpoint, as well as in terms of model chemistry and economic advantages of the biological system. The chemical approaches aimed at duplicating the biological process are presented.

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Potential for Nitrogen Fixation in Maize Genotypes in Brazil

Cited by 260 publications

References 6 publications

Isolation of Acetylene-reducing Spirilla from the Roots of Potamogeton filiformis from Loch Leven (Kinross)

Isolation of Acetylene-reducing Spirilla from the Roots of Potamogeton filiformis from Loch Leven (Kinross)

Nitrogenase Activity Associated with Roots and Stems of Field-Grown Corn (Zea mays L.) Plants

Nitrogen Fixation

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