Persistence of introduced strains of Rhizobium leguminosarum bv trifolii in acidic soils of north-eastern Victoria

1999 ◽  
Vol 39 (7) ◽  
pp. 829 ◽  
Author(s):  
J. F. Slattery ◽  
D. R. Coventry

Summary. A 5-year study was undertaken to establish if introduced rhizobia with higher tolerance to Al than the current inoculant Rhizobium can persist and continue nodulating subterranean clover (Trifolium subterraneum L.) in acidic soils. Two Rhizobium leguminosarum bv trifolii strains were introduced as seed inoculants with subterranean clover at 2 acidic sites (pHCa 4.1 and pHCa 4.3), where lime and gypsum had been applied as soil amendments. Strain NA3001 was selected for its tolerance to high Al concentrations when grown on an agar medium and WU95, which is a widely used commercial inoculant strain, for its relatively poor tolerance to Al when grown on agar. Liming the soil increased its pH and reduced the concentration of extractable Al at both sites. In the year the subterranean clover was sown, strain WU95 had nodule occupancy of 20–49%, decreasing with time to 4–7% after 5 seasons (1991–95). The nodule occupancy of strain NA3001 was initially lower than strain WU95 (14–16%), but its occupancy did not vary with time (significant strain x time interactions, P<0.05). These data indicate that the acid-tolerant strain NA3001 has the potential to persist in these strongly acidic soils and, despite the presence of high background populations of naturalised rhizobia, to continue initiating nodulation. The use of soil amendments (lime and gypsum) to increase pH and reduce soluble Al concentrations did not affect the nodule occupancy of either NA3001 or WU95 with time, nor did it slow the rate of decline in nodule occupancy of WU95.

1997 ◽  
Vol 37 (6) ◽  
pp. 623 ◽  
Author(s):  
P. E. Quigley ◽  
P. J. Cunningham ◽  
M. Hannah ◽  
G. N. Ward ◽  
T. Morgan

Summary. The whole-soil inoculation method was used to assess the symbiotic effectiveness of rhizobia populations in soils collected from 18 randomly-selected pastures in south-western Victoria. This was part of a larger study which described the condition of pasture within this region. Based on the shoot weights of test subterranean clover plants, cv. Mount Barker, effectiveness varied from 36 to 94% depending on the site of rhizobia collection. This range was wider than that found in an earlier survey of rhizobia effectiveness conducted nearby. WU95, the commercial inoculant for subterranean clover, was significantly more effective than 9 of the rhizobia samples. Rhizobia from 2 sites were especially poor and their effectiveness (37%) was not significantly different from the nil inoculum control (28%). Symbiotic effectiveness was not related to soil pH, available sulfur, available phosphorus, total nitrogen or mean annual rainfall for each site where rhizobia were collected. After pooling data for all sites, the shoot weights were significantly related to the proportions of plants with nodules assigned high nodulation scores. In contrast, low scores, within 1 of 6 categories, did not significantly affect shoot weight. The technique of using mean nodulation score was less capable of discriminating differences in symbiotic effectiveness, compared with assessment based on test plant weight.


Plants ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1630
Author(s):  
Ana Paço ◽  
José Rodrigo da-Silva ◽  
Denise Pereira Torres ◽  
Bernard R. Glick ◽  
Clarisse Brígido

Manganese (Mn) toxicity is a very common soil stress around the world, which is responsible for low soil fertility. This manuscript evaluates the effect of the endophytic bacterium Pseudomonas sp. Q1 on different rhizobial-legume symbioses in the absence and presence of Mn toxicity. Three legume species, Cicer arietinum (chickpea), Trifolium subterraneum (subterranean clover), and Medicago polymorpha (burr medic) were used. To evaluate the role of 1-aminocyclopropane-1-carboxylate (ACC) deaminase produced by strain Q1 in these interactions, an ACC deaminase knockout mutant of this strain was constructed and used in those trials. The Q1 strain only promoted the symbiotic performance of Rhizobium leguminosarum bv. trifolii ATCC 14480T and Ensifer meliloti ATCC 9930T, leading to an increase of the growth of their hosts in both conditions. Notably, the acdS gene disruption of strain Q1 abolished the beneficial effect of this bacterium as well as causing this mutant strain to act deleteriously in those specific symbioses. This study suggests that the addition of non-rhizobia with functional ACC deaminase may be a strategy to improve the pasture legume–rhizobial symbioses, particularly when the use of rhizobial strains alone does not yield the expected results due to their difficulty in competing with native strains or in adapting to inhibitory soil conditions.


2002 ◽  
Vol 29 (7) ◽  
pp. 907
Author(s):  
Louise F. Roddam ◽  
Wendy R. Lewis-Henderson ◽  
Michael A. Djordjevic

The nodulation failure resulting from the interaction between Rhizobium leguminosarum biovar trifolii strain ANU794 and the Trifolium subterraneum cv. Woogenellup was examined by transposon mutagenesis to resolve whether multiple determinants were involved in cultivar-specificity. Three new transposon-induced mutants of ANU794 (W72, W78 and W710) with significantly enhanced nodulation ability on cv. Woogenellup were identified. The W72 and W78 mutations are chromosomally-located, whereas the W710 mutation isplasmid-located. The ethylene synthesis inhibitor, aminoethoxyvinylglycine, fails to enhance the nodulation ability of ANU794, ANU7943 (csn1::Tn5) and W78 on cv. Woogenellup, but enhances the nodulation ability of W72,W710 and ANU7941 (nodM::Tn5). DNA sequencing of the W78 locus reveals strong homology to an unknown Mycobacterium open reading frame, and to several bacterial non-haem chloroperoxidases. The previously identified csn1 locus showed homology to the 50S ribosomal protein, L9, with the Tn5 insertion being located in the 5′-untranslated region. The results suggest that cultivar-specificity is mediated by at least two independent mechanisms or determinants, and not by a simple gene-for-gene interaction. The role of ethylene in cultivar specificity is discussed. Cultivar-specific interactions may prove useful in identifying pathways involved in efficient nodule formation and plant-microbe interactions.


2015 ◽  
Vol 66 (11) ◽  
pp. 1197 ◽  
Author(s):  
Leo J. Hamilton ◽  
Kevin F. M. Reed ◽  
Elainne M. A. Leach ◽  
John Brockwell

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.


1968 ◽  
Vol 19 (6) ◽  
pp. 891 ◽  
Author(s):  
AH Gibson ◽  
J Brockwell

An examination was made of the ability of lines of Trifolium subterraneum L. subsp. subterraneum, subsp. yanninicum Katzn. et Morley, and subsp. brachycalycinum Katzn. et Morley to nodulate and fix nitrogen with strains of .Rlzizobium trifolii isolated from habitats dominated by each of the subspecies.Host line x bacterial strain specificity was demonstrated at two levels: (a) some strains nodulated one, or two, host lines ineffectively, yet formed an effective symbiosis with the other host lines; (b) among the symbiotic combinations classed as effective, the degree of effectiveness of the strains was dependent on the host lines. It was found that the lines of a subspecies were not more effectively nodulated by the bacterial strains isolated from a habitat in which that subspecies was the predominant subterranean clover, than they were by strains isolated from habitats in which the other subspecies predominated. For example, lines of T. subterraneum subsp. yanninicum fixed nitrogen as well with strains of R. trifolii isolated from habitats of subsp. subterraneum or subsp. brachycalycinum as they did with strains isolated from its own habitat. Similarly, there was little evidence that the strains from the habitat in which a subspecies predominated were more effective in their symbiosis with the lines of that subspecies than they were with the lines of the other subspecies. The only exception to this latter generalization was that the strains isolated from the subsp. brachycalycinum habitat were slightly more effective with subsp. brachycalycinum than with subspp. yanninicum or subterraneum. Groupings of the strains based on their response with the lines of any subspecies, or with the lines of all subspecies combined, bore no relation to groupings based on the origin of the strains. It was concluded that it was not possible to predict the effectiveness of any symbiotic combination from a consideration of the taxonomy of the host or the habitat from which the bacterium was isolated. The feasibility of using a standard host line for the screening of the general effectiveness of all strains of potential value in subterranean clover inoculants is discussed. The commercial inoculant strain, TA1, was not the most effective strain with all lines, and overall, ranked fifth among the strains examined.


2002 ◽  
Vol 29 (4) ◽  
pp. 473 ◽  
Author(s):  
Louise F. Roddam ◽  
Wendy R. Lewis-Henderson ◽  
Michael A. Djordjevic

The nodulation failure resulting from the interaction between Rhizobium leguminosarum biovar trifolii strain ANU794 and the Trifolium subterraneum cv. Woogenellup was examined by transposon mutagenesis to resolve whether multiple determinants were involved in cultivar-specificity. Three new transposon-induced mutants of ANU794 (W72, W78 and W710) with significantly enhanced nodulation ability on cv. Woogenellup were identified. The W72 and W78 mutations are chromosomally-located, whereas the W710 mutation isplasmid-located. The ethylene synthesis inhibitor, aminoethoxyvinylglycine, fails to enhance the nodulation ability of ANU794, ANU7943 (csn1::Tn5) and W78 on cv. Woogenellup, but enhances the nodulation ability of W72,W710 and ANU7941 (nodM::Tn5). DNA sequencing of the W78 locus reveals strong homology to an unknown Mycobacterium open reading frame, and to several bacterial non-haem chloroperoxidases. The previously identified csn1 locus showed homology to the 50S ribosomal protein, L9, with the Tn5 insertion being located in the 5′-untranslated region. The results suggest that cultivar-specificity is mediated by at least two independent mechanisms or determinants, and not by a simple gene-for-gene interaction. The role of ethylene in cultivar specificity is discussed. Cultivar-specific interactions may prove useful in identifying pathways involved in efficient nodule formation and plant-microbe interactions.


1968 ◽  
Vol 19 (6) ◽  
pp. 907 ◽  
Author(s):  
AH Gibson

The symbiotic relationship between Trifolium subterraneum L. cv. Woogenellup and a number of strains of Rhizobium trifolii was examined in tube and pot culture experiments. Plants grown in agar culture with the roots darkened and at 22°C either failed to nodulate or formed nodules slowly when inoculated with a number of strains; with other strains nodulation was prompt and the effectiveness levels were similar to those achieved with other subterranean clover cultivars. Exposure of the roots to light in tube culture experiments promoted nodulation by the "slowly nodulating" strains; higher root temperatures (28°) also promoted nodulation. Nine samples of the cultivar from widely separated sources behaved in a similar manner. Approximately 50% of 287 field isolates of R. trifolii from three localities were slow to nodulate this host, even when the roots were exposed to light. The proportion of field isolates nodulating the host promptly, and the effectiveness of nodulation achieved varied within and between the localities from which the isolations were made. R. trifolii strain TA1 failed to nodulate Woogenellup adequately in a pot culture experiment with two soils differing in the size of their natural population of R. trifolii (< 2/g, 104/g). Under the same conditions, three other strains formed a high proportion (> 80%) of the nodules in both soils, as determined by serological analysis of isolates from the nodules. A competition study with mixed inoculants showed that strain CC2480a formed a higher proportion of the nodules on cv. Woogenellup than strains WA67 or WU290, the present commercial inoculant strains. The results are discussed in relation to conflicting reports of poor nodulation of Woogenellup in the field, and of satisfactory nodulation in the laboratory and the glasshouse.


2017 ◽  
Vol 68 (8) ◽  
pp. 805
Author(s):  
Leo J. Hamilton ◽  
Kevin F. M. Reed ◽  
Elainne M. A. Leach ◽  
John Brockwell

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.


2011 ◽  
Vol 62 (10) ◽  
pp. 903 ◽  
Author(s):  
E. A. Drew ◽  
N. Charman ◽  
R. Dingemanse ◽  
E. Hall ◽  
R. A. Ballard

Naturalised soil rhizobia that nodulate clover occur in high number and are known to vary in their symbiotic performance (SP) with subterranean clover (Trifolium subterraneum L.). However, the extent of suboptimal fixation across a range of other clover species is not well understood. T. subterraneum and nine other annual clover species of Mediterranean origin were evaluated for their SP in combination with the naturalised clover rhizobia in 71 Australian soils and five strains of Rhizobium leguminosarum bv. trifolii that have been used in the inoculants produced for clovers. The most probable number method, using subterranean clover as the trap plant was used to estimate the number of clover rhizobia in the soils. Ninety-two percent of soils tested contained more than 1000 rhizobia/g. An extract of each soil, or strain of rhizobia was used to inoculate plants growing in N-deficient media in the greenhouse. Plants were grown for 4 weeks after inoculation and shoot dry matter determined and expressed as a percentage of the ‘best’ soil rhizobia treatment, to provide a proportional measure of SP for each clover species. SP (mean of clover species) ranged from 96% with the current inoculant strain for annual clovers (WSM1325) down to 48% with former inoculant strain WU95. When inoculated with soils predominantly from mainland Australia, SP (mean of soil treatments) of the different Trifolium spp. was 55% (resupinatum), 53–47% (subterraneum), 50% (nigrescens), 49% (michelianum), 48% (isthmocarpum), 38% (hirtum), 35% (purpureum), 32% (vesiculosum), 25% (spumosum) and 21% (glanduliferum). Within each of the clover species, SP resulting from individual soil treatments ranged from 100% (by definition for the best soil treatment) down to close to zero. Trifolium glanduliferum formed nodules readily with the inoculant strains but nodulation was erratic with the rhizobia in many soils. It is therefore proposed that the naturalised rhizobia in many soils are unlikely to be inoculant strains. This research demonstrates symbiotic efficiency across annual clover species is compromised where diverse populations of clover rhizobia have naturalised in soils.


2001 ◽  
Vol 41 (8) ◽  
pp. 1149 ◽  
Author(s):  
J. Evans ◽  
P. Eberbach ◽  
D. Luckett ◽  
S. Cormack

In soils with a resident population of symbiotically effective rhizobia in sufficient number that legume inoculation is not a requirement for successful legume cropping, greater flexibility may be exercised in the use of legume seed dressings that are toxic to rhizobia. Inoculating crops antecedent to legume crops has been suggested as a method for pre-establishing effective inoculant rhizobia in soil. The extent to which this strategy (pre-inoculation) would remove the need for inoculating legume seed (conventional inoculation) was tested for Bradyrhizobium sp. (Lupinus) and Rhizobium leguminosarum bv. viciae with crops of lupin (Lupinus angustifolius) and faba bean (Vicia faba), respectively. In the glasshouse, in pasteurised sand and red kandosol, the numbers of B. sp. (Lupinus) in the rhizospheres of wheat (Triticum aestivum), canola (Brassica campestris) and clover (Trifolium subterraneum) increased 300–10000-fold over a 14-week period, reaching numbers similar to that achieved on L. angustifolius. These increases were not greatly affected by chemical seed dressings commonly applied to the crops: on wheat, Vincit C and Baytan C; on canola and subterranean clover, Lemat. In the sandy soil, the nodulation of lupin following pre-establishment of rhizobia, drying and mixing of soil, was not improved by conventional inoculation; in the red kandosol nodulation was increased only marginally by conventional inoculation. The results with the glasshouse pot trials warranted further investigation in the field. Under field conditions, when B. sp. (Lupinus) was pre-established with wheat, on a red kandosol in south-western New South Wales, the number of these bacteria surviving in the dry soil at the end of the wheat phase was much lower than in the glasshouse study. In the following season, the nodulation of lupin sown without inoculant, and dependent only on pre-established rhizobia, was significantly reduced, as compared with that on conventionally inoculated lupin. An exception occurred where the lupin was dry-sown 3 weeks before rain, in which case nodulation was comparatively poor even with conventional inoculation. Reduced nodulation was generally consistent with initially fewer rhizobia in the lupin rhizosphere. However, the numbers of rhizobia were eventually similar to those found with conventional inoculation. In the third year, in autumn, B. sp. (Lupinus) was abundant in the soil in all treatments and there were no differences in lupin nodulation between treatments. Similarly, introducing R. leguminosarum bv. viciae on wheat, in an acidic red kandosol in south-western New South Wales, failed to provide as much nodulation of faba bean as was achieved with conventional inoculation. The maximal dry matter of the bean crop was also significantly lower with pre-inoculation as compared to conventional inoculation.


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