Competition between effective and ineffective strains of Rhizobium trifolii in the nodulation of Trifolium subterraneum

1969 ◽  
Vol 20 (5) ◽  
pp. 827 ◽  
Author(s):  
AC Robinson
Keyword(s):  
Competitive Ability ◽  
Root Nodule ◽  
Effective Strain ◽  
Substantial Reduction ◽  
Trifolium Subterraneum ◽  
Bacterial Cells ◽  
Rhizobium Trifolii ◽  
Parallel Study ◽  
Nodule Bacteria ◽  
Tube Culture

The competitive ability of effective and ineffective strains of Rhizobium trifolii to form nodules on two cultivars of Trifolium subterraneum was examined under bacteriologically controlled conditions in tube culture. Seedlings were inoculated with mixtures of known numbers each of effective and of ineffective strains and the strains forming the nodules subsequently determined. In all instances, the effective strains formed a much greater proportion of nodules than would be expected from the relative numbers of each strain in the inoculum. Moreover, a reduction in the numbers of an effective strain relative to the numbers of an ineffective strain failed to result in a corresponding increase in the proportion of nodules formed by an ineffective strain. Instead, the ratio of ineffective to effective strains had to be of the order of 108/104 or wider (c. 10,000/1) before there was a substantial reduction in the number of nodules formed by the effective strains. Even when this ratio was of the order of 108/102, the effective strains still produced some of the nodules. A parallel study of the rates of nodulation of seedlings inoculated with mixtures of strains showed that these rates were characteristic of the proportions of nodules being formed by each strain. Subsequently seedlings were inoculated with mixtures of effective and ineffective strains, and after 66, 90, and 114 hr the roots were surface-sterilized and their contents isolated and identified. Independently of the mixture of strains used, most of the bacterial cells were identified as the effective strains. Because the strains of effective and ineffective bacteria used produce nodules freely when inoculated separately onto these hosts, it is postulated that the hosts distinguished between effective and ineffective strains, and that this recognition is related to compatibility in association with the host. The significance of the results in relation to studies of the root-nodule bacteria is discussed.

scholarly journals The Symbiotic Synthesis of Auxin by Legumes and Nodule Bacteria and its Eole in Nodule Development

1960 ◽  
Vol 13 (4) ◽  
pp. 456 ◽  
Author(s):  
NP Kefford ◽  
J Brockwell ◽  
JA Zwar
Keyword(s):  
Acetic Acid ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Nodule Development ◽  
Distilled Water ◽  
Rhizobium Trifolii ◽  
Nodule Bacteria ◽  
Root Medium ◽  
Growth Properties ◽  
Indole 3 Acetic Acid

When subterranean clover (Trifolium subterraneum L.) plants were grown for 3 weeks over distilled water, tryptophan could be detected in the root medium of both sterile cultures and those inoculated with Rhizobium trifolii 3 days earlier. Auxin could be detected only in the inoculated medium. The auxin had the chromatographic and growth properties of indole�3-acetic acid (IAA). Since nodule bacteria produce auxin only in the presence of tryptophan, which is a probable precursor of lAA, it is suggested that the tryptophan exuded by clover roots is converted to lAA by nodule bacteria. Auxin was still produced in the root medium when strains of Rhizobium which do not nodulate subterranean olover roots were used as inooulant, or when nitrate, which delays nodulation, was present in the medium.

Boron deficiency in pasture based on subterranean clover (Trifolium subterraneum L.) is linked to symbiotic malfunction

2015 ◽  
Vol 66 (11) ◽  
pp. 1197 ◽  
Author(s):  
Leo J. Hamilton ◽  
Kevin F. M. Reed ◽  
Elainne M. A. Leach ◽  
John Brockwell
Keyword(s):  
N2 Fixation ◽  
Rhizobium Leguminosarum ◽  
Root Nodule ◽  
Effective Strain ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Boron Deficiency ◽  
Initial Application ◽  
Clover Root ◽  
Clover Seed

Field and glasshouse experiments confirmed the occurrence of boron (B) deficiency in subterranean clover (Trifolium subterraneum L.) pasture in eastern Victoria. Diminished productivity was linked to the small-seededness of clover and the poor effectiveness of clover root-nodule bacteria (rhizobia, Rhizobium leguminosarum bv. trifolii). Productivity, especially of clover and clover seed, increased following applications of up to 6 kg B ha–1 (P < 0.001). The response was delayed, occurring several years after the initial application of B, unless the land was resown with fresh clover seed inoculated with an effective strain of rhizobia. B deficiency in the nodulated legume induced conditions within the plant and or its rhizobia that led to impaired nitrogen (N2) fixation. Glasshouse research indicated that populations of soil-borne rhizobia taken from B-deficient soils were poorly effective in N2 fixation and that rhizobia from soils growing subterranean clover cv. Leura were significantly less effective (P < 0.05) than rhizobia from a soil growing cv. Mt Barker. Additionally, subterranean clover seed generated in B-deficient soils was at least one-third smaller than the seed of commercial seed but responded to inoculation with effective rhizobia. This indicated that any symbiotic malfunction of clover from B-deficient soils was not due to an inability to respond to nitrogen per se. On the other hand, cv. Leura from B-deficient soils fixed significantly less N2 than commercial cv. Leura when each was inoculated with rhizobia from B-deficient soils.

Genetic control of strain-specific ineffective nodulation in Trifolium subterraneum L.

1964 ◽  
Vol 15 (1) ◽  
pp. 37 ◽  
Author(s):  
AH Gibson
Keyword(s):  
Genetic Control ◽  
Bacterial Strain ◽  
Similar Pattern ◽  
Root Nodule ◽  
Major Gene ◽  
Trifolium Subterraneum ◽  
Nodule Bacteria ◽  
Root Nodule Bacteria ◽  
Parent Variety ◽  
Early Parent

The nodulation response of the Trifolium subterraneum variety Northam First Early with a range of strains of root nodule bacteria has been investigated. An ineffective response was found with the normally effective bacterial strain NA30. Within F2 populations of crosses between Northam First Early and each of six other varieties of T. subterraneum, the response to inoculation with strain NA30 varied from fully ineffective through intermediate effectiveness to fully effective. The proportion of ineffectively noddated plants in these F, populations was also influenced by the non- Northam First Early parent variety. Differences in response among individual plants within the F, populations were probably due to the segregation of a single major gene and a number of modifying genes. Of 10 other strains examined, one strain showed a similar pattern of response to that obtained with NA30, while a second strain exhibited host x strain specific ineffectiveness of a different type.

Host selection for effective Rhizobium trifolii by red clover and subterranean clover in the field

1969 ◽  
Vol 20 (6) ◽  
pp. 1053 ◽  
Author(s):  
AC Robinson
Keyword(s):  
Host Selection ◽  
Root Nodule ◽  
Red Clover ◽  
Subterranean Clover ◽  
Mixed Population ◽  
Rhizobium Trifolii ◽  
Nodule Bacteria ◽  
Heterologous Host ◽  
Selection For ◽  
Test Plants

Cultures of root-nodule bacteria, from the nodules of red clover and subterranean clover growing closely together in the field, were tested for comparative symbiotic ability (effectiveness) with both red clover and subterranean clover. It was found that test plants of either host species nodulated faster and more effectively when inoculated with cultures isolated from the homologous host growing in the field than did test plants inoculated with cultures isolated from the heterologous host. Because the hosts had originally been nodulated in the presence of the same field populations of Rhizobium trifolii, it is concluded that the host legume exerts a selective effect in accepting infections from a mixed population.

Ecological studies of root-nodule bacteria introduced into field environments. II. Initial competition between seed inocula in the nodulation of Trifolium subterraneum L. seedlings

1968 ◽  
Vol 19 (5) ◽  
pp. 749 ◽  
Author(s):  
J Brockwell ◽  
WF Dudman
Keyword(s):  
Natural Population ◽  
Root Nodule ◽  
Field Experiments ◽  
Trifolium Subterraneum ◽  
Nodule Bacteria ◽  
Naturally Occurring ◽  
Diffusion Technique ◽  
Rhizobium Strains ◽  
Clover Seed ◽  
Legume Inoculants

The ability of three strains of Rhizobium trifolii used in legume inoculants to form nodules on inoculated Trifolium subterraneum L. was examined in field experiments on a soil containing a large natural population of clover rhizobia. The identity of cultures isolated from nodules on young seedlings was established by a gel immune diffusion technique. When a mixture of broth and peat inocula was applied to seed, a large proportion of nodules was attributable to peat-borne rhizobia. In competition with the natural population in the production of nodules on the roots of the host legume, strain WA67 = TA1 > UNZ29. In competition with each other as well as with the naturally occurring rhizobia, WA67 > TAI > UNZ29. The significance of the findings in relation to the persistence in soil of Rhizobium strains applied as inoculant to clover seed is discussed.

The root-nodule bacteria as factors in clover establishment in the red basaltic soils of the Lismore district, NSW. III. Field inoculation trials.

1954 ◽  
Vol 5 (1) ◽  
pp. 77 ◽  
Author(s):  
HV Jenkins ◽  
JM Vincent ◽  
LM Waters
Keyword(s):  
Root Nodule ◽  
Effective Strain ◽  
Fertilizer Treatment ◽  
Nodule Bacterium ◽  
Nodule Bacteria ◽  
Field Inoculation ◽  
Red Soils ◽  
Basaltic Soils ◽  
Successful Inoculation ◽  
Heavy Dose

Field experience with crimson and subterranean clovers grown in the Lismore red soils has confirmed the importance of successful inoculation with an effective strain of a root-nodule bacterium. Strains of rhizobia, applied singly or in a mixture, differed markedly in their ability to form nodules in the red soils. A relatively heavy dose of inoculum (c. 10 times the usual) was desirable. Superphosphate and dolomite were favourable to nodulation but a trace element mixture that included copper sulphate at the rate of 10 lb per acre proved markedly toxic when put in the drill with inoculated seed. Yield was directly related to the proportion of plants effectively nodulated, whether the latter varied because of the nature of the inoculum or because of fertilizer treatment. Results of inoculation at other centres in the district were very satisfactory. Success has also been obtained with the inoculation of Medicago, pea, and vetch.

STUDIES ON THE LEGUME ROOT NODULE BACTERIA: II. THE PRODUCTION AND BEHAVIOR OF COLONIAL MUTANTS PRODUCED BY X-RAY IRRADIATION

1952 ◽  
Vol 30 (2) ◽  
pp. 125-130 ◽  
Author(s):  
D. C. Jordan
Keyword(s):  
Root Nodule ◽  
Effective Strain ◽  
Sterile Plant ◽  
Nodule Bacteria ◽  
Artificial Medium ◽  
Serial Transfer ◽  
Root Nodule Bacteria ◽  
X Ray ◽  
Colonial Morphology ◽  
And Behavior

Four distinct types of colonial mutation were obtained by X-ray irradiation of a parasitic strain of alfalfa Rhizobium. Two types were procured from an effective strain. Colonial morphology remained stable throughout serial transfer on artificial medium, but changed considerably after one plant passage. Three variants derived from the parasitic parent were found to be efficient in nitrogen fixation when tested by sterile plant growth procedures and the Virtanen technique. This efficiency increased during the course of two plant passages. Colonial variation and effectivity changes occurred independently of one another.

Ecological studies of root-nodule bacteria introduced into field environments. 3. Persistence of Rhizobium trifolii in association with white cover at high elevations

1972 ◽  
Vol 12 (57) ◽  
pp. 407 ◽  
Author(s):  
J Brockwell ◽  
WG Bryant ◽  
RR Gault
Keyword(s):  
White Clover ◽  
Root Nodule ◽  
New South ◽  
Single Step ◽  
Rhizobium Trifolii ◽  
Nodule Bacteria ◽  
Legume Seed ◽  
South Wales ◽  
Inoculant Strain ◽  
High Elevations

Eight strains of Rhizobium trifolii were tested for ability to persist in association with white clover (Trifolium repens) sown at three sites at different elevations in the Snowy Mountains region of New South Wales. The standard clover inoculant strain, TA1, persisted poorly. Five strains of Tasmanian origin (representing two distinct serotypes), all highly effective in nitrogen fixation in combination with white clover, were recovered from the soils at high frequency over a period of three years. A single-step technique of pelleting and seed inoculation was slightly but consistently superior to the more complicated method that has been employed routinely for inoculation of legume seed used in revegetation undertakings in the Snowy Mountains.

Corrigendum to: Boron deficiency in pasture based on subterranean clover (Trifolium subterraneum L.) is linked to symbiotic malfunction

2017 ◽  
Vol 68 (8) ◽  
pp. 805
Author(s):  
Leo J. Hamilton ◽  
Kevin F. M. Reed ◽  
Elainne M. A. Leach ◽  
John Brockwell
Keyword(s):  
N2 Fixation ◽  
Rhizobium Leguminosarum ◽  
Root Nodule ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Boron Deficiency ◽  
Nodule Bacteria ◽  
Clover Root ◽  
Per Se ◽  
Clover Seed

Field and glasshouse experiments confirmed the occurrence of boron (B) deficiency in subterranean clover (Trifolium subterraneum L.) pasture in eastern Victoria. Diminished productivity was linked to the small-seededness of clover and the poor effectiveness of clover root-nodule bacteria (rhizobia, Rhizobium leguminosarum bv. trifolii). Productivity, especially of clover and clover seed, increased following applications of up to 6 kg B ha–1 (P B deficiency in the nodulated legume induced conditions within the plant and or its rhizobia that led to impaired nitrogen (N2) fixation. Glasshouse research indicated that populations of soil-borne rhizobia taken from B-deficient soils were poorly effective in N2 fixation and that rhizobia from soils growing subterranean clover cv. Leura were significantly less effective (P Additionally, subterranean clover seed generated in B-deficient soils was at least one-third smaller than the seed of commercial seed but responded to inoculation with effective rhizobia. This indicated that any symbiotic malfunction of clover from B-deficient soils was not due to an inability to respond to nitrogen per se. On the other hand, cv. Leura from B-deficient soils fixed significantly less N2 than commercial cv. Leura when each was inoculated with rhizobia from B-deficient soils.

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