scholarly journals The morphogenesis of lupine root nodules during infection by Rhizobium lupini

2014 ◽  
Vol 56 (4) ◽  
pp. 687-703 ◽  
Author(s):  
Władysław Golinowski ◽  
Joanna Kopcińska ◽  
Wojciech Borucki
Keyword(s):  
Structural Changes ◽  
Root Nodules ◽  
Root Hairs ◽  
Lupinus Luteus ◽  
Stages Of Development ◽  
Root Cortex ◽  
Parenchyma Cells ◽  
Rhizobium Lupini ◽  
Infected Cells ◽  
Cytological Characteristics

The development of root nodules in <em>Lupinus luteus</em> infected by <em>Rhizobium lupini</em> was studied using cytological methods. The results obtained from examination of material sampled 6, 9, 13, 15, 20, 29 and 60 days after infection are given. The successive stages of development are described and the cytological characteristics of the tissue are presented. The mitotic divisions of the root cortex parenchyma cells, which initiated the formation of the nodule primordium, were accompanied by structural changes in the root hairs and divisions in the root pericycle. The development of the nodule was associated with the activity of the lateral meristems, which encompass both the infected cells and cells not containing bacteroids Characteristics of bacteria found in the symplast and apoplast of the bacteroid tissue are given.

scholarly journals Nodulation of Aeschynomene afraspera and A. indica by Photosynthetic Bradyrhizobium Sp. Strain ORS285: The Nod-Dependent Versus the Nod-Independent Symbiotic Interaction

2011 ◽  
Vol 24 (11) ◽  
pp. 1359-1371 ◽  
Author(s):  
Katia Bonaldi ◽  
Daniel Gargani ◽  
Yves Prin ◽  
Joel Fardoux ◽  
Djamel Gully ◽  
...  
Keyword(s):  
Fluorescent Protein ◽  
Lateral Roots ◽  
Root Hairs ◽  
Infection Process ◽  
Cortical Cells ◽  
Symbiotic Interaction ◽  
Root Cortex ◽  
Bradyrhizobium Sp ◽  
Infected Cells ◽  
Green Fluorescent

Here, we present a comparative analysis of the nodulation processes of Aeschynomene afraspera and A. indica that differ in their requirement for Nod factors (NF) to initiate symbiosis with photosynthetic bradyrhizobia. The infection process and nodule organogenesis was examined using the green fluorescent protein–labeled Bradyrhizobium sp. strain ORS285 able to nodulate both species. In A. indica, when the NF-independent strategy is used, bacteria penetrated the root intercellularly between axillary root hairs and invaded the subepidermal cortical cells by invagination of the host cell wall. Whereas the first infected cortical cells collapsed, the infected ones immediately beneath kept their integrity and divided repeatedly to form the nodule. In A. afraspera, when the NF-dependent strategy is used, bacteria entered the plant through epidermal fissures generated by the emergence of lateral roots and spread deeper intercellularly in the root cortex, infecting some cortical cells during their progression. Whereas the infected cells of the lower cortical layers divided rapidly to form the nodule, the infected cells of the upper layers gave rise to an outgrowth in which the bacteria remained enclosed in large tubular structures. Together, two distinct modes of infection and nodule organogenesis coexist in Aeschynomene legumes, each displaying original features.

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.

Development of Alnus japonica root nodules after inoculation with Frankia strain HFPArI3

1987 ◽  
Vol 65 (8) ◽  
pp. 1647-1657 ◽  
Author(s):  
D. Burgess ◽  
R. L. Peterson
Keyword(s):  
Root Nodules ◽  
Root Hairs ◽  
Vascular Cylinder ◽  
Alnus Japonica ◽  
Frankia Strain ◽  
Cortical Cells ◽  
Starch Grains ◽  
Transmission Electron ◽  
Exotic Tree ◽  
Infected Cells

The ontogeny and structure of nodules on an exotic tree species, Alnus japonica (Thunb.) Steud. were studied for up to 3 months after inoculation of seedlings with a North American Frankia strain, HFPArI3. Nodules developed with Frankia growth first restricted to one side of the developing vascular cylinder. Nodules became multilobed, developed a complex network of vascular cylinders, and infected cortical cells organized in a concentric ring around each vascular cylinder. Each nodule lobe showed a zonation from the meristem basipetally. Cortical cells adjacent to the meristem contained hyphae, while those distal to this zone developed hyphae and endophytic vesicles. Staining for suberin induced fluorescence of root hairs, the endodermal Casparian strip, endophytic vesicle clusters, and periderm. Staining for callose resulted in fluorescence of the encapsulation material at one stage of Frankia development. Infected cells had few, small starch grains, while uninfected cells had several, large starch grains. The adjacent pericycle was multilayered. Its cells, viewed with the transmission electron microscope, had lobed nuclei, small vacuoles, many mitochondria, and dense plastids containing small starch grains.

The occurrence of infected cells, with persistent infection threads, in legume root nodules

1987 ◽  
Vol 65 (3) ◽  
pp. 553-558 ◽  
Author(s):  
Sergio M. de Faria ◽  
Shona G. McInroy ◽  
Janet I. Sprent
Keyword(s):  
Root Nodules ◽  
Root Hairs ◽  
Infection Process ◽  
Wall Material ◽  
Cell Wall Material ◽  
Legume Trees ◽  
Infection Threads ◽  
Host Cell Wall ◽  
Infected Cells ◽  
Intercellular Spread

A survey of the structure of nodules from primitive legume trees was conducted. All genera examined in the subfamily Caesalpinioideae, some from the Papilionoideae, but none from the Mimosoideae had cells in the central, nitrogen-fixing region in which bacteria were confined by host cell wall material in structures resembling infection threads. However, infection of these cells occurred by intercellular spread of rhizobia rather than by infection threads. It is suggested that infection threads may have evolved in infected cells and later extended to early stages of the infection process including entry into root hairs.

scholarly journals Development of Functional Symbiotic White Clover Root Hairs and Nodules Requires Tightly Regulated Production of Rhizobial Cellulase CelC2

2011 ◽  
Vol 24 (7) ◽  
pp. 798-807 ◽  
Author(s):  
Marta Robledo ◽  
José I. Jiménez-Zurdo ◽  
M. José Soto ◽  
Encarnación Velázquez ◽  
Frank Dazzo ◽  
...  
Keyword(s):  
Cell Wall ◽  
White Clover ◽  
Rhizobium Leguminosarum ◽  
Plant Cell Wall ◽  
Root Nodules ◽  
Root Hairs ◽  
Nitrogen Fixing ◽  
Plant Host ◽  
Root Cortex ◽  
Infection Threads

The establishment of rhizobia as nitrogen-fixing endosymbionts within legume root nodules requires the disruption of the plant cell wall to breach the host barrier at strategic infection sites in the root hair tip and at points of bacterial release from infection threads (IT) within the root cortex. We previously found that Rhizobium leguminosarum bv. trifolii uses its chromosomally encoded CelC2 cellulase to erode the noncrystalline wall at the apex of root hairs, thereby creating the primary portal of its entry into white clover roots. Here, we show that a recombinant derivative of R. leguminosarum bv. trifolii ANU843 that constitutively overproduces the CelC2 enzyme has increased competitiveness in occupying aberrant nodule-like root structures on clover that are inefficient in nitrogen fixation. This aberrant symbiotic phenotype involves an extensive uncontrolled degradation of the host cell walls restricted to the expected infection sites at tips of deformed root hairs and significantly enlarged infection droplets at termini of wider IT within the nodule infection zone. Furthermore, signs of elevated plant host defense as indicated by reactive oxygen species production in root tissues were more evident during infection by the recombinant strain than its wild-type parent. Our data further support the role of the rhizobial CelC2 cell wall–degrading enzyme in primary infection, and show evidence of its importance in secondary symbiotic infection and tight regulation of its production to establish an effective nitrogen-fixing root nodule symbiosis.

Effective and ineffective root nodules in Myrica faya

1976 ◽  
Vol 194 (1116) ◽  
pp. 285-293 ◽  
Keyword(s):  
Root Nodules ◽  
Light And Electron Microscopy ◽  
Nodule Formation ◽  
Culture Solution ◽  
Myrica Gale ◽  
Main Site ◽  
Myrica Faya ◽  
Modern Methods ◽  
Infected Cells ◽  
Nodule Endophytes

In cross-inoculation trials, inocula containing the nodule endophytes of Myrica gale, M. cerifera, M. cordifolia and M. pilulifera respectively were applied to the roots of young plants of M. faya Ait. growing in nitrogen-free culture solution. All four inocula induced nodule formation, and except where the M. gale inoculum had been used the nodules were of effective type and enabled the plants bearing them to grow nearly as well as other M. faya plants associated with the normal endophyte. The nodules induced by the M. gale endophyte were very numerous, but remained small and fixed no significant amount of nitrogen, and were thus ineffective. Light and electron microscopy showed that in the effective nodules induced by the normal endophyte or by that of M. cordifolia , the endophyte was confined to a layer 1-2 cells deep near the middle of the nodule cortex, and that in respect of the width of the hyphae and their production of club-shaped internally subdivided vesicles, the endophytes resembled closely those in the nodules of the few other species of Myrica that have been studied by modern methods of microscopy. In ineffective nodules the disposition of the infected cells was unchanged, but within the cells only a sparse development of the endophyte was observed, and no vesicles were found. The finding that nodules lacking vesicles showed little or no fixation is consistent with other evidence that the vesicles normally produced by non-legume nodule endophytes are the main site of nitrogen fixation.

scholarly journals Zika virus replication in glioblastoma cells: electron microscopic tomography shows 3D arrangement of endoplasmic reticulum, replication organelles, and viral ribonucleoproteins

2021 ◽  
Author(s):  
Johannes Wieland ◽  
Stefan Frey ◽  
Ulrich Rupp ◽  
Sandra Essbauer ◽  
Rüdiger Groß ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Line ◽  
Zika Virus ◽  
Structural Changes ◽  
Electron Tomography ◽  
Glioblastoma Cells ◽  
Electron Microscopic ◽  
N Protein ◽  
Ribonucleoprotein Complexes ◽  
Infected Cells

AbstractStructural changes of two patient-derived glioblastoma cell lines after Zika virus infection were investigated using scanning transmission electron tomography on high-pressure-frozen, freeze-substituted samples. In Zika-virus-infected cells, Golgi structures were barely visible under an electron microscope, and viral factories appeared. The cytosol outside of the viral factories resembled the cytosol of uninfected cells. The viral factories contained largely deranged endoplasmic reticulum (ER), filled with many so-called replication organelles consisting of a luminal vesicle surrounded by the ER membrane. Viral capsids were observed in the vicinity of the replication organelles (cell line #12537 GB) or in ER cisternae at large distance from the replication organelles (cell line #15747 GB). Near the replication organelles, we observed many about 100-nm-long filaments that may represent viral ribonucleoprotein complexes (RNPs), which consist of the RNA genome and N protein oligomers. In addition, we compared Zika-virus-infected cells with cells infected with a phlebovirus (sandfly fever Turkey virus). Zika virions are formed in the ER, whereas phlebovirus virions are assembled in the Golgi apparatus. Our findings will help to understand the replication cycle in the virus factories and the building of the replication organelles in glioblastoma cells.

Morphological and biochemical changes in peanut nodules during photosynthate stress

1992 ◽  
Vol 38 (6) ◽  
pp. 526-533 ◽  
Author(s):  
A. B. M. Siddique ◽  
A. K. Bal
Keyword(s):  
Nitrogen Fixation ◽  
Root Nodules ◽  
Ultrastructural Level ◽  
Malate Synthase ◽  
Morphological Evidence ◽  
Lipid Bodies ◽  
Biochemical Status ◽  
Short Period ◽  
Infected Cells ◽  
Ultrastructural Damage

Nitrogen fixation in legume root nodules is believed to be supported by the supply of photosynthate of the current photoperiod. However, in peanut nodules, prolonged periods of darkness or detopping do not disrupt nitrogen fixation for at least 48 h. During this period, nodule oleosomes (lipid bodies) have been shown to decrease in number within the infected cells, and it has been suggested that lipids from oleosomes are mobilized to maintain the energy and carbon requirements of the nitrogen-fixing nodules. We present morphological evidence, at the ultrastructural level, for the utilization of oleosomes during photosynthate stress. The biochemical status of the nodule has also been assessed and correlated with ultrastructure. For comparison cowpea nodules were used that totally lacked oleosomes. In peanut nodules leghemoglobin and total protein remained unchanged along with integrated ultrastructure on nodule cells for 48 h, whereas in cowpea a decline in proteins with ultrastructural damage became apparent within a very short period of photosynthate stress. In peanut nodules empty or partially empty oleosomes were taken as evidence for their utilization during the stress period. Key words: N2 fixation, photosynthate stress, lipid bodies, catalase, malate synthase, peanut nodule, β-oxidation.

scholarly journals Heterologous Expression of Rhizobial CelC2 Cellulase Impairs Symbiotic Signaling and Nodulation in Medicago truncatula

2018 ◽  
Vol 31 (5) ◽  
pp. 568-575 ◽  
Author(s):  
Marta Robledo ◽  
Esther Menéndez ◽  
Jose Ignacio Jiménez-Zurdo ◽  
Raúl Rivas ◽  
Encarna Velázquez ◽  
...  
Keyword(s):  
Medicago Truncatula ◽  
Cell Walls ◽  
Rhizobium Leguminosarum ◽  
Root Nodules ◽  
Root Hairs ◽  
Nod Factors ◽  
Model Legume ◽  
Ensifer Meliloti ◽  
Early Nodulin ◽  
The Impact

The infection of legume plants by rhizobia is tightly regulated to ensure accurate bacterial penetration, infection, and development of functionally efficient nitrogen-fixing root nodules. Rhizobial Nod factors (NF) have key roles in the elicitation of nodulation signaling. Infection of white clover roots also involves the tightly regulated specific breakdown of the noncrystalline apex of cell walls in growing root hairs, which is mediated by Rhizobium leguminosarum bv. trifolii cellulase CelC2. Here, we have analyzed the impact of this endoglucanase on symbiotic signaling in the model legume Medicago truncatula. Ensifer meliloti constitutively expressing celC gene exhibited delayed nodulation and elicited aberrant ineffective nodules, hampering plant growth in the absence of nitrogen. Cotreatment of roots with NF and CelC2 altered Ca2+ spiking in root hairs and induction of the early nodulin gene ENOD11. Our data suggest that CelC2 alters early signaling between partners in the rhizobia-legume interaction.

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