FUNGI ASSOCIATED WITH LEGUME ROOT NODULES AND THEIR EFFECT ON RHIZOBIA

1966 ◽  
Vol 12 (6) ◽  
pp. 1253-1261 ◽  
Author(s):  
P. K. Chhonkar ◽  
N. S. Subba-Rao
Keyword(s):  
Rhizobium Leguminosarum ◽  
Rhizobium Meliloti ◽  
Root Nodules ◽  
Antibiotic Activity ◽  
Rhizobium Japonicum ◽  
Trifolium Alexandrinum ◽  
Rhizobium Trifolii ◽  
Rhizobium Phaseoli ◽  
Fresh Weight ◽  
Rhizobium Sp

Fungi associated with the nodules of nine common legumes were isolated and identified. The nodules had a mycoflora consisting of Cephalosporium, Alternaria, Aspergillus, Penicillium, Rhizopus, Acrothecium, Fusarium, Rhizoctonia, Curvularia, Pythium, and Trichoderma. Mycoflora of nodules of Trifolium alexandrinum was also analyzed in relation to the age of the plant and the volume of nodules. The fungi were screened for antibiotic activity towards six species of rhizobia. The results showed that Rhizobium trifolii, Rhizobium phaseoli, Rhizobium leguminosarum, and Rhizobium japonicum were relatively more susceptible to fungal antibiotics than either Rhizobium meliloti or Rhizobium sp. (cowpea group). Mycocolonization in soil by an isolate of Cephalosporium sp. significantly reduced the fresh weight and nitrogen status of T. alexandrinum.

Typing of Rhizobium by phages

1970 ◽  
Vol 16 (10) ◽  
pp. 1003-1009 ◽  
Author(s):  
Ryszard Staniewski
Keyword(s):  
Rhizobium Leguminosarum ◽  
Rhizobium Meliloti ◽  
Rhizobium Trifolii ◽  
Rhizobium Phaseoli ◽  
Group Iii ◽  
Phage Types ◽  
Group I ◽  
Rhizobium Lupini ◽  
Distinguished Group ◽  
Established Group

Two hundred and thirty strains of Rhizobium trifolii, Rhizobium leguminosarum for pea, vetch, horse bean, and Lathyrus spp., Rhizobium phaseoli and Rhizobium meliloti were subjected to phage typing. On the basis of their sensitivity to phages these strains were divided into three groups: I, II, and III.In group I, consisting of R. trifolii, R. leguminosarum for pea, vetch, and horse bean, and R. phaseoli, 18 phage types were established. Group II included some strains of R. trifolii and R. leguminosarum for pea and vetch. Among them three phage types were distinguished. Group III included R. meliloti strains and one strain of Rhizobium lupini for lupine. In that group 10 phage types were found.

Genetic characterization of Rhizobium sp. strain TAL1145 that nodulates tree legumes

1994 ◽  
Vol 40 (3) ◽  
pp. 208-215 ◽  
Author(s):  
M. L. C. George ◽  
J. P. W. Young ◽  
D. Borthakur
Keyword(s):  
Rhizobium Leguminosarum ◽  
Genetic Characterization ◽  
Rhizobium Meliloti ◽  
Wild Type ◽  
Tree Legumes ◽  
Wide Range ◽  
The Common ◽  
Rrna Sequences ◽  
Rhizobium Sp

Rhizobium sp. strain TALI 145 nodulates Leucaena ieucocephaia and Phaseolus vulgaris, in addition to a wide range of tropical tree legumes. Six overlapping clones that complemented nodulation defects in leucaena and bean rhizobia were isolated and a 40-kb map of the symbiosis region was constructed. The common nod and nifA genes were situated approximately 17 kb apart, with the nodlJ genes in between. These clones enabled a derivative of TAL1145 carrying a partially deleted pSym to form ineffective nodules on both leucaena and bean, and a similar derivative of Rhizobium etli TAL182 to form ineffective nodules on bean. When two representative clones, pUHR9 and pUHR114, were each transferred to wild-type rhizobial strains, they allowed ineffective nodulation by Rhizobium meliloti on both leucaena and bean and by Rhizobium leguminosarum bv. viciae on bean. Transconjugants of R. leguminosarum bv. trifolii formed effective nodules on leucaena and ineffective nodules on bean. Tn5 mutagenesis of the symbiosis region resulted in a variety of nodulation and fixation phenotypes on leucaena and bean. On the basis of 16S rRNA sequences, TAL1145 was found to be distinct from both R. tropici and NGR234, the two groups of leucaena symbionts that were previously described.Key words: Rhizobium, Leucaena leucocephala, nodulation, nitrogen fixation.

Gene Expression of Medicago sativa Inoculated with Sinorhizobium meliloti as Modulated by the Xenobiotics Cadmium and Fluoranthene

2000 ◽  
Vol 55 (3-4) ◽  
pp. 222-232 ◽  
Author(s):  
Heike Neumann ◽  
Dietrich Werner
Keyword(s):  
Gene Expression ◽  
Arabidopsis Thaliana ◽  
Medicago Sativa ◽  
Sinorhizobium Meliloti ◽  
Rhizobium Meliloti ◽  
Root Nodules ◽  
Cadmium Concentration ◽  
Transcript Level ◽  
Northern Hybridization ◽  
Fresh Weight

Abstract Alfalfa plants (Medicago sativa cv. Europe) inoculated with Sinorhizobium meliloti 2011 (formerly Rhizobium meliloti, de Lajudie et al., 1994) were cultivated for 14 days under standardized growth conditions in mineral medium with addition of the heavy metal cadmium or the polycyclic aromatic hydrocarbon fluoranthene. These xenobiotics significantly reduced the numbers of root nodules before any visible damage to the plant could be detected. EC10. EC50, and EC90 (effective concentrations reducing nodulation, shoot and root fresh weight by 10, 50, or 90% compared to the control without pollutant) were calculated. EC50 for cadmium ranged from 5.8 jam (nodulation) to more than 20 μᴍ (root fresh weight). Testing fluoranthene resulted in an EC50 of 2.5 μg cm-2 for nodulation, and EC50 values of more than 35 μg cm-2 for shoot and root biomass production, indicating that the effect parameter nodulation is 10-fold more sensitive than shoot and root fresh weight. With m RNA differential display techniques the effects of both xenobiotics on gene expression in alfalfa root systems were studied. 37 differentially displayed transcripts were detected. Two of them, called DDMs1 and DDMs2, were confirmed by northern hybridization to be down-regulated in the presence of the xenobiotics. The expression of transcript DDMs1 was enhanced in alfalfa control plants inoculated with rhizobia, the transcript level was increased 2.5-3-fold compared to non-inoculated plants. This positive effect of nodulation was suppressed, partly by 35 μg cm-2 fluoranthene and totally by 20 μᴍ cadmium. The decrease in DDMsl transcription was highly affected by the cadmium concentration with an EC50 of 5.9 μᴍ . Compared to nodulation, almost identical EC10, EC50. and EC90 values were found for DDMsl expression. Sequence analysis of DDMsl revealed a significant overall homology (50% identity) to a hypothetical protein from Arabidopsis thaliana with high similarity to a copper transporting ATPase. High levels of transcript DDMs2 were observed in control plants with a 50% decrease in the xenobiotic-treated plants. DDM s2 gave a strong homology (82% identity) to the cytoplasmatic 60S ribosomal protein L18 from Arabidopsis thaliana.

Formation and structure of root nodules induced on Macroptilium atropurpureum inoculated with various species of Rhizobium

1991 ◽  
Vol 69 (7) ◽  
pp. 1520-1532 ◽  
Author(s):  
Michael J. Trinick ◽  
Celia Miller ◽  
Paul A. Hadobas
Keyword(s):  
Rhizobium Leguminosarum ◽  
Rhizobium Meliloti ◽  
Root Nodules ◽  
Matrix Material ◽  
Immunogold Labelling ◽  
Infection Threads ◽  
Glass Tubes ◽  
Infected Cells ◽  
Macroptilium Atropurpureum ◽  
Nodule Tissue

Fifteen strains of Rhizobium leguminosarum biovar trifolii formed ineffective nodules and (or) nodule-like structures (rhizobia were re-isolated from both structures) on Macroptilium atropurpureum grown in enclosed glass tubes. Bacteria were observed among the parenchyma cells surrounding the nodule-like structures. One variant of R. leguminosarum biovar trifolii (NGR66/ST) isolated from M. atropurpureum formed nodules on this host that exhibited abnormal intercellular and intracellular infection. The bacteria (NGR66/ST) were contained within threadlike structures, surrounded by matrix material. The identities of the Rhizobium strains were confirmed serologically after reisolation and in sections of nodule tissue using immunogold labelling. Rhizobium leguminosarum biovar phaseoli strain NGR76 isolated from Phaseolus vulgaris formed nodules on M. atropurpureum resembling those formed by effective Bradyrhizobium strains. The association was partially effective in nitrogen fixation, and this was reflected in the nodule structure. The percentage of cells infected was lower than that in fully effective nodules. There was a high frequency of infected cells showing degeneration; these were located throughout the nodule tissue and were often adjacent to healthy infected cells. The rhizobia appeared to infect new nodule cells via infection threads, which were abundant both intercellularly and intracellularly in young, mature, and degenerating host nodule cells. Strains of R. leguminosarum biovar viceae and Rhizobium meliloti were unable to induce nodule-like structures on M. atropurpureum. Key words: Macroptilium, Bradyrhizobium, Rhizobium, microscopy, nodule, structure.

Nitrate reductase activities of rhizobia and the correlation between nitrate reduction and nitrogen fixation

1979 ◽  
Vol 25 (10) ◽  
pp. 1169-1174 ◽  
Author(s):  
James R. Manhart ◽  
Peter P. Wong
Keyword(s):  
Nitrogen Fixation ◽  
Nitrate Reductase ◽  
Nitrate Reduction ◽  
Nitrate Reductase Activity ◽  
Reductase Activity ◽  
Root Nodules ◽  
Sole Source ◽  
Rhizobium Japonicum ◽  
Rhizobium Trifolii ◽  
Rhizobium Species

All species of Rhizobium except R. lupini had nitrate reductase activity. Only R. lupini was incapable of growth with nitrate as the sole source of nitrogen. However, the conditions necessary for the induction of nitrate reductase varied among species of Rhizobium. Rhizobium japonicum and some Rhizobium species of the cowpea strains expressed nitrate reductase activities both in the root nodules of appropriate leguminous hosts and when grown in the presence of nitrate. Rhizobium trifolii, R. phaseoli, and R. legnminosarum did not express nitrate reductase activities in the root nodules, but they did express them when grown in the presence of nitrate. In bacteroids of R. japonicum and some strains of cowpea Rhizobium, high N2 fixation activities were accompanied by high nitrate reductase activities. In bacteroids of R. trifolii, R. leguminosarum, and R. phaseoli, high N2 fixation activities were not accompanied by high nitrate reductase activities.

scholarly journals Morphology of root nodules and nodule-like structures formed by Rhizobium and Agrobacterium strains containing a Rhizobium meliloti megaplasmid.

1983 ◽  
Vol 97 (3) ◽  
pp. 787-794 ◽  
Author(s):  
C H Wong ◽  
C E Pankhurst ◽  
A Kondorosi ◽  
W J Broughton
Keyword(s):  
Normal Development ◽  
Rhizobium Meliloti ◽  
Root Nodules ◽  
Root Hairs ◽  
Host Cells ◽  
Donor Strain ◽  
Intercellular Spaces ◽  
Infection Threads ◽  
Infected Cells ◽  
Rhizobium Sp

We examined expression of the megaplasmid pRme41b of Rhizobium meliloti in two different Rhizobium sp. Strains and in Agrobacterium tumefaciens. Transfer of pRme41b into these bacteria was facilitated by insertion of a recombinant plasmid coding for mobilization functions of RP4 into the nif region (Kondorosi, A., E. Kondorosi, C.E. Pankhurst, W. J. Broughton, and Z. Banfalvi, 1982, Mol. Gen. Genet., 188:433-439). In all cases, transconjugants formed nodule-like structures on the roots of Medicago sativa. These structures were largely composed of meristematic cells but they were not invaded by bacteria. Bacteria were found only within infection threads in root hairs, and within intercellular spaces of the outermost cells of the structures. The donor strain of R. meliloti containing pAK11 or pAK12 in pRme41b initially produced nodules on M. sativa that did not fix nitrogen (Fix-). In these nodules, bacteria were released from infection threads into the host cells but they did not multiply appreciably. Any bacteroids formed degenerated prematurely. In some cases, however, reversion to a Fix+ phenotype occurred after 4 to 6 wk. Bacteria released into newly infected cells in these nodules showed normal development into bacteriods.

Catalase activity and nitrogen fixation in legume root nodules

1972 ◽  
Vol 18 (6) ◽  
pp. 861-864 ◽  
Author(s):  
A. J. Francis ◽  
Martin Alexander
Keyword(s):  
Nitrogen Fixation ◽  
White Clover ◽  
Catalase Activity ◽  
Oxidase Activity ◽  
Root Nodules ◽  
Phenol Oxidase ◽  
Rhizobium Japonicum ◽  
Rhizobium Trifolii ◽  
Phenol Oxidase Activity ◽  
Japonicum Strain

Effective white clover and soybean nodules contained more catalase than ineffective nodules. The catalase activity of a Rhizobium japonicum strain collected from effective soybean nodules was greater than that in a strain from the ineffective root structures. Ineffective Rhizobium trifolii mutants grown in laboratory media had less catalase than their effective parent strains, but no relationship between catalase content and effectiveness was noted among laboratory-grown R. japonicum cultures. Effective nodules from soybean but not from white clover were somewhat richer in peroxidase than the analogous non-nitrogen-fixing root structures. No correlation was evident between effectiveness and phenol-oxidase activity of soybean nodules.

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