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.

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.

scholarly journals Localization of Superoxide Dismutases and Hydrogen Peroxide in Legume Root Nodules

2004 ◽  
Vol 17 (12) ◽  
pp. 1294-1305 ◽  
Author(s):  
Maria C. Rubio ◽  
Euan K. James ◽  
Maria R. Clemente ◽  
Bruna Bucciarelli ◽  
Maria Fedorova ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Enzyme Inhibitors ◽  
Root Nodules ◽  
Strong Support ◽  
Immunogold Electron Microscopy ◽  
Superoxide Dismutases ◽  
Signal Molecule ◽  
Infection Threads ◽  
Infected Cells ◽  
Nodule Tissue

Superoxide dismutases (SODs) catalyze the dismutation of superoxide radicals to O2 and H2O2 and thus represent a primary line of antioxidant defense in all aerobic organisms. H2O2 is a signal molecule involved in the plant's response to pathogen attack and other stress conditions as well as in nodulation. In this work, we have tested the hypothesis that SODs are a source of H2O2 in indeterminate alfalfa (Medicago sativa) and pea (Pisum sativum) nodules. The transcripts and proteins of the major SODs of nodules were localized by in situ RNA hybridization and immunogold electron microscopy, respectively, whereas H2O2 was localized cytochemically by electron microscopy of cerium-perfused nodule tissue. The transcript and protein of cytosolic CuZnSOD are most abundant in the meristem (I) and invasion (II) zones, interzone II-III, and distal part of the N2-fixing zone (III), and those of MnSOD in zone III, especially in the infected cells. At the subcellular level, CuZnSOD was found in the infection threads, cytosol adjacent to cell walls, and apoplast, whereas MnSOD was in the bacteroids, bacteria within infection threads, and mitochondria. The distinct expression pattern of CuZnSOD and MnSOD suggests specific roles of the enzymes in nodules. Large amounts of H2O2 were found at the same three nodule sites as CuZnSOD but not in association with MnSOD. This colocalization led us to postulate that cytosolic CuZnSOD is a source of H2O2 in nodules. Furthermore, the absence or large reduction of H2O2 in nodule tissue preincubated with enzyme inhibitors (cyanide, azide, diphenyleneiodonium, diethyldithiocarbamate) provides strong support to the hypothesis that at least some of the H2O2 originates by the sequential operation of an NADPH oxidase- like enzyme and CuZnSOD. Results also show that there is abundant H2O2 associated with degrading bacteroids in the senescent zone (IV), which reflects the oxidative stress ensued during nodule senescence.

Organization of microtubules in developing pea root nodule cells

2001 ◽  
Vol 79 (7) ◽  
pp. 777-786
Author(s):  
A L Davidson ◽  
W Newcomb
Keyword(s):  
Rhizobium Leguminosarum ◽  
Root Nodule ◽  
Root Nodules ◽  
Cell Cortex ◽  
Cortical Microtubules ◽  
Microtubule Organization ◽  
Pea Root ◽  
Fluorescence And Electron Microscopy ◽  
Infected Cells ◽  
Cytoplasmic Microtubules

Pisum sativum L. (pea) root nodule cells undergo many cellular changes in response to infection by Rhizobium leguminosarum bv. viciae. These include cell growth, organelle reorganization, and changes relating to the increase in the number of bacteria within the cell. The objective of this study was to characterize microtubule organization during nodule cell development. The organization of microtubules was examined in developing pea root nodules using fluorescence and electron microscopy techniques. Immunolabelling of microtubules in meristematic cells showed diffuse fluorescence in the cell cortex and adjacent to the nuclear envelope. Recently infected cells contained randomly oriented cortical microtubules and cytoplasmic microtubules that were fragmented with diffuse fluorescence. Infected cells contained an extensive network of long, randomly arranged cortical microtubules with some parallel bundles. Cytoplasmic microtubules in single optical sections of infected cells appeared as short undulating filaments; however, overlapping images from a Z-series of an infected cell showed that the microtubules are long and wavy, and generally radiate inward from the cell cortex.Key words: nodule, microtubules, Rhizobium, pea, symbiosis.

scholarly journals Morphogenesis of root nodules in white clover. II. The effect of mutation in genes nod IJ of the microsymbiont upon the nodule structure

2014 ◽  
Vol 67 (1) ◽  
pp. 5-22
Author(s):  
Barbara Łotocka ◽  
Joanna Kopcińska ◽  
Władysław Golinowski
Keyword(s):  
White Clover ◽  
Rhizobium Leguminosarum ◽  
Root Nodules ◽  
Single Cells ◽  
Wild Strain ◽  
Root Hairs ◽  
Nodule Development ◽  
Wild Type ◽  
Delayed Reaction ◽  
Infection Threads

Morphogenesis of ineffective root nodules initiated on the roots of white clover 'Astra' by the <em>Rhizobium leguminosarum</em> biovar. <em>trifolii</em> strains ANU261 (Tn5 insertion in nod 1 gene) and ANU262 (Tn5 insertion in nod J gene) was investigated. Following changes were observed, as compared to the wild-type nodulation: the exaggerated, not delayed reaction of root hairs; the delay in nodulation with the number of nodules the same as in plants inoculated with a wild strain; the formation and organization of the nodule primordium not changed in comparison with the wild-type nodules; infection threads abnormally branched and diffusing with bacteria deprived of light zone and enriched with storage material; infected cells of bacteroidal tissue abnormally strongly osmiophilic and only slightly vacuolated; symbiosomes with very narrowed peribacteroidal space, subject to premature degradation; abnormal accumulation of starch in the nodule tissues; nodule development blocked at the stage of laterally situated meristem and single nodule bundle; inhibition of divisions in the meristem and vacuolation of its cells; the appearance of single cells with colonies of saprophytic rhizobia embedded in the fibrillar matrix in the old, degraded regions of the bacteroidal tissue.

Indirect evidence for cellulase production by Rhizobium in pea root nodules during bacteroid differentiation: cytochemical aspects of cellulose breakdown in rhizobial droplets

1989 ◽  
Vol 35 (9) ◽  
pp. 821-829 ◽  
Author(s):  
François-P. Chalifour ◽  
Nicole Benhamou
Keyword(s):  
Rhizobium Leguminosarum ◽  
Root Nodules ◽  
Hydrolytic Enzyme ◽  
Indirect Evidence ◽  
Cellulase Production ◽  
Cytochemical Localization ◽  
Thin Walls ◽  
Sequence Of Events ◽  
Infection Threads ◽  
Cellulose Breakdown

Cytochemical localization of cellulosic β-(1–4) glucans in pea (Pisum sativum L.) nodules at different stages of infection by an effective isolate of Rhizobium leguminosarum biovar viceae was studied using a gold-complexed exoglucanase. Cellulose subunits were present in great amounts in root cell walls, as shown by intense and regular labeling by gold particles. Labeling was unevenly distributed over the thin walls of emerging infection threads. In more developed infection threads, labeling was more intense and evenly distributed than in emerging threads, although slightly altered, unlabeled wall areas were frequently observed at the growing tips. Droplets containing rhizobia, which originated from infection threads, were surrounded by labeled wall-like material. Rhizobial droplets were either single- or multi-celled, and were sometimes separated by inner, unevenly labeled compartments. The surrounding wall-like material was irregularly labeled, and unlabeled wall areas, neighbouring intensely labeled ones, were observed frequently. There was an absence of labeling ahead of the rhizobia that escaped from the droplets, but degenerating wall-like material was present around the escaping rhizobia, mainly on their sides. At more advanced stages of development, labeling was present only over the outermost wall layers of rhizobial droplets, indicating that inner portions were degraded first. These observations suggest that a hydrolytic enzyme is involved in the sequence of events from infection thread formation through rhizobial release in the host cell cytoplasm, and that the hydrolytic enzyme is of rhizobial origin.Key words: Rhizobium–Pisum symbiosis, root nodules, rhizobial droplets, cellulose, colloidal gold.

scholarly journals Identification of a Family of Extensin-Like Glycoproteins in the Lumen of Rhizobium-Induced Infection Threads in Pea Root Nodules

2002 ◽  
Vol 15 (4) ◽  
pp. 350-359 ◽  
Author(s):  
Elizabeth A. Rathbun ◽  
Michael J. Naldrett ◽  
Nicholas J. Brewin
Keyword(s):  
Posttranscriptional Regulation ◽  
Rhizobium Leguminosarum ◽  
Root Nodules ◽  
Regulation Of Gene Expression ◽  
Pcr Primers ◽  
Amino Acid Sequences ◽  
Sequence Conservation ◽  
Host Cells ◽  
Cdna Clones ◽  
Infection Threads

Rhizobium leguminosarum bv. viciae normally gains access to pea host cells through tubular cell wall ingrowths termed infection threads. Matrix glycoprotein (MGP), a major component of the infection thread lumen, is also secreted from the tips of uninoculated roots and can be released into solution under reducing conditions. Monoclonal antibody MAC265, which recognizes MGP through a carbohydrate epitope, was used for immunoaffinity purification of the glycoprotein from pea roots. Following treatment with chymotrypsin, a peptide fragment was obtained and subjected to N-terminal sequencing. Using PCR primers based on this sequence, cDNA clones were isolated with RNA from inoculated roots and nodules. DNA sequencing of 30 of these clones revealed a family of closely related and repetitive polypeptides with (hydroxy)proline-rich motifs. The cDNA sequences showed over 70% identity with the deduced amino acid sequences of plant extensins, particularly with VfNDS-E from Vicia faba and MtN12 from Medicago truncatula, both of which are strongly upregulated in legume root nodules. Root nodule extensins from pea were of variable length but showed strong sequence conservation of the N-terminus, of the C-terminus, and of a central domain comprising 33 amino acids that were sometimes reiterated. The distribution of tyrosine residues suggested the possible importance of intramolecular and intermolecular cross-linking. There was strong sequence conservation with MtN12 in the 3′-untranslated region, suggesting a possible involvement in posttranscriptional regulation of gene expression.

Comparison of the genomic arrangement and the relative transcription of the nitrogenase genes in Rhizobium meliloti during symbiotic development in alfalfa root nodules

1982 ◽  
Vol 28 (12) ◽  
pp. 1330-1339 ◽  
Author(s):  
Alan S. Paau ◽  
Winston J. Brill
Keyword(s):  
Rhizobium Meliloti ◽  
Protein Pattern ◽  
Root Nodules ◽  
Symbiotic Association ◽  
Free Living ◽  
Genomic Arrangement ◽  
Infection Threads ◽  
Nitrogenase Genes ◽  
Specific Amplification ◽  
Alfalfa Root

In the course of the symbiotic development of free-living rhizobia to mature bacteroids in alfalfa nodules, mRNA transcripts of the nitrogenase structural genes are first detected when the rhizobia are inside the infection threads. These transcripts are most abundant in the mature bacteroids of young (6 to 8 weeks) root nodules and are present in a much lower level in bacteroids from senescent root nodules (13 weeks). Translation of these and related rhizobial genes essential for the symbiotic association apparently occurs very early in the symbiosis because the protein pattern of the "infection thread rhizobia" is very similar to that of the mature bacteroids and is different from that of the cultured vegetative rhizobia. Although bacteroids have a higher DNA content than the vegetative bacteria and are very different in the nucleoid organization, no specific amplification or rearrangement of the nitrogenase genes is detected in bacteroids.

scholarly journals Morphogenesis of root nodules in white clover. III. The effect of mutation in nod IJ genes of the microsymbiont upon the DNA level in the host tissue

2014 ◽  
Vol 67 (1) ◽  
pp. 23-29
Author(s):  
Barbara Łotocka ◽  
Władysław Golinowski
Keyword(s):  
White Clover ◽  
Rhizobium Leguminosarum ◽  
Root Nodule ◽  
Nuclear Dna ◽  
Root Nodules ◽  
Root Hairs ◽  
Infection Threads ◽  
Dna Contents ◽  
Mutant Strains ◽  
Nuclear Dna Contents

On the basis of cytophotometric measurements a slightly increased DNA level in the nuclei of curled root hairs containing infection threads was observed in white clover inoculated with wild and mutant strains of <em>Rhizobium leguminosarum</em> biovar. <em>trifolii</em>, as compared to normal root hairs of te same plants. Cells of the root nodule primordia in 72 h after the inoculation, as compared to the root primary cortex, demonstrated an increased level of the nuclear DNA. No differences were observed in the nuclear DNA contents in individual layers of the cortex of the 28 day-old nodules. Generally it was low, varying from 2c to 4c. The meristematic and bacteroidal tissues in the effective nodules were characterized by a higher DNA level, as compared to the respective zones in ineffective nodules induced with the strains ANU261 (<em>nod I<sup>*</sup></em>) and ANU262 (<em>nod J<sup>*</sup></em>). The DNA level in the effective bacteroidal tissue varied from 4c to 32c, while in the tissue containing the strain ANU26l only the 2c-8c nuclei could be found and in the tissue with the strain ANU262 - the 4c-16c nuclei.

scholarly journals The Structure of Ineffective Root Nodules of Legumes: An Unusual New Type of Ineffectiveness, and an Appraisal of Present Knowledge

1957 ◽  
Vol 10 (3) ◽  
pp. 233 ◽  
Author(s):  
FJ Bergersen
Keyword(s):  
Root Nodules ◽  
Subterranean Clover ◽  
Present Knowledge ◽  
Host Tissue ◽  
Bacterial Strains ◽  
Nodule Bacteria ◽  
Infection Threads ◽  
New Type ◽  
Slow Growing ◽  
Nodule Tissue

A new type of symbiotic ineffectiveness in subterranean clover is described in which very slow-growing nodules are produced. In these the nodule bacteria are not released from the infection threads, where they multiply at the expense of the host tissue. Comparison of nuclear size of normal effective nodules with that of these ineffective nodules suggests that the nodule tissue is almost devoid of the disomatic cells in which the nitrogen-fixing bacteroid form of Rhizobium normally develops. The bacterial strains giving rise to these nodules were obtained as stable variants of a strain producing structurally and cytologically normal nodules.

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