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.

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.

Structure and host–actinomycete interactions in developing root nodules of Comptonia peregrina

1978 ◽  
Vol 56 (5) ◽  
pp. 502-531 ◽  
Author(s):  
William Newcomb ◽  
R. L. Peterson ◽  
Dale Callaham ◽  
John G. Torrey
Keyword(s):  
Host Cell ◽  
Root Nodules ◽  
Host Cells ◽  
Electron Microscopic ◽  
Cortical Cells ◽  
Host Cytoplasm ◽  
Transmission Electron ◽  
Microscopic Studies ◽  
Host Plasma Membrane ◽  
Soil Actinomycete

Correlated fluorescence, bright-field, transmission electron, and scanning electron microscopic studies were made on developing root nodules of Comptonia peregrina (L.) Coult. (Myricaceae) produced by a soil actinomycete which invades the root and establishes a symbiosis leading to fixation of atmospheric dinitrogen. After entering the host via a root hair infection, the hyphae of the endophyte perforate root cortical cells by local degradation of host cell walls and penetration of the host cytoplasm. The intracellular hyphae are always surrounded by host plasma membrane and a thick polysaccharide material termed the capsule. (For convenience, term intracellular refers to the endophyte being inside a Comptonia cell as distinguished from being intercellular, i.e.. between host cells, even though the former is actually extracellular as the endophyte is separated from the host cytoplasm by the host plasmalemma.) Numerous profiles of vesiculate rough endoplasmic reticulum (RER) occur near the growing hyphae. Although the capsule shows a positive Thiery reaction indicating its polysaccharide nature, the fibrillar contents of the RER do not, leaving uncertain whether the capsule results from polymers derived from the RER. Amyloplasts of the cortical cells lose their starch deposits during hyphal proliferation. The hyphae branch extensively in specific layers of the cortex, penetrating much of the host cytoplasm. At this stage, hyphal ends become swollen and form septate club-shaped vesicles within the periphery of the host cells. Lipid-like inclusions and Thiery-positive particles, possibly glycogen, are observed in the hyphae at this time. Associated with hyphal development is an increase in average host cell volume, although nuclear volume appears to remain constant. Concomitant with vesicle maturation, the mitochondrial population increases sharply, suggesting a possible relationship to vesicle function. The intimate interactions between host and endophyte during development of the symbiotic relationship are emphasized throughout.

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 Silencing of Putative Cytokinin Receptor Histidine Kinase1 Inhibits Both Inception and Differentiation of Root Nodules in Arachis hypogaea

2018 ◽  
Vol 31 (2) ◽  
pp. 187-199 ◽  
Author(s):  
Anindya Kundu ◽  
Maitrayee DasGupta
Keyword(s):  
Arachis Hypogaea ◽  
Root Nodules ◽  
Nodule Development ◽  
Response Regulators ◽  
Cytokinin Signaling ◽  
Cortical Cells ◽  
Cytokinin Receptor ◽  
Undifferentiated State ◽  
Mitotic Cyclin ◽  
Infected Cells

Rhizobia–legume interaction activates the SYM pathway that recruits cytokinin signaling for induction of nodule primordia in the cortex. In Arachis hypogaea, bradyrhizobia invade through natural cracks developed in the lateral root base and are directly endocytosed in the cortical cells to generate the nodule primordia. To unravel the role of cytokinin signaling in A. hypogaea, RNA-interference (RNAi) of cytokinin receptor histidine-kinase1 (AhHK1) was done. AhHK1-RNAi downregulated the expression of type-A response regulators such as AhRR5 and AhRR3 along with several symbiotic genes, indicating that both cytokinin signaling and the SYM pathway were affected. Accordingly, there was a drastic downregulation of nodulation in AhHK1-RNAi roots and the nodules that developed were ineffective. These nodules were densely packed, with infected cells having a higher nucleo-cytoplasmic ratio and distinctively high mitotic index, where the rod-shaped rhizobia failed to differentiate into bacteroids within spherical symbiosomes. In accordance with the proliferating state, expression of a mitotic-cyclin AhCycB2.1 was higher in AhHK1-RNAi nodules, whereas expression of a retinoblastoma-related (AhRBR) nodule that restrains proliferation was lower. Also, higher expression of the meristem maintenance factor WUSCHEL-RELATED HOMEOBOX5 correlated with the undifferentiated state of AhHK1-RNAi nodules. Our results suggest that AhHK1-mediated cytokinin signaling is important for both inception and differentiation during nodule development in A. hypogaea.

The life cycle of Lagena radicicola, an oomycetous parasite of wheat roots

1990 ◽  
Vol 68 (4) ◽  
pp. 813-824 ◽  
Author(s):  
D. J. S. Barr ◽  
N. L. Désaulniers
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Life Cycle ◽  
Root Hairs ◽  
Wheat Roots ◽  
Virus Like Particles ◽  
Transmission Electron ◽  
Resting Spores ◽  
Single Host ◽  
Infected Cells

Lagena radicicola Vanterpool & Ledingham is an obligate parasite inside root hairs and epidermal cells. It was cultured in a unifungal state on wheat in pots. The life cycle was examined by both light and transmission electron microscopy. The thallus developed inside a single host cell and formed either a single sporangium or one to four resting spores. Zoospore cleavage was completed in vesicles outside the root. The resting spores were similar to oospores in their development and cytology, but there was no evidence of cell fusion and sexuality. Virus-like particles were seen in 3- to 12-month-old cultures, and infected cells became degenerate. Key words: Oomycetes, ultrastructure, virus-like particles, biocontrol.

Fine structure of the root nodules of Dryas drummondii Richards (Rosaceae)

1981 ◽  
Vol 59 (12) ◽  
pp. 2500-2514 ◽  
Author(s):  
William Newcomb
Keyword(s):  
Fine Structure ◽  
Root Nodules ◽  
Host Cells ◽  
Vascular Cylinder ◽  
Cortical Cells ◽  
Polysaccharide Capsule ◽  
Nodule Morphology

The root nodules of Dryas drummondii (common name: mountain avens; Family Rosaceae) possess numerous nodule lobes devoid of nodule roots and thus they exhibit the Alnus-type of nodule morphology. Each nodule lobe possesses a nodule meristem, infected cortical cells, and a central vascular cylinder. The endophyte is prokaryotic and has two forms: septate hyphae, 0.3–0.6 μm in diameter, and nonseptate vesicles, ca. 2 μm in diameter; thus, the endophyte appears to be an actinomycete similar to those of other Frankia-induced nodules. A polysaccharide capsule surrounds both forms of the endophyte and contains numerous electron-dense inclusions near the hyphae in host cells containing both forms of the endophyte.

Host–endophyte interactions in effective and ineffective nodules induced by the endophyte of Myrica gale

1983 ◽  
Vol 61 (11) ◽  
pp. 2898-2909 ◽  
Author(s):  
Kathryn A. VandenBosch ◽  
John G. Torrey
Keyword(s):  
Nitrogenase Activity ◽  
Root Nodules ◽  
Seedling Development ◽  
Nodule Development ◽  
Nodule Formation ◽  
Cortical Tissue ◽  
Intercellular Spaces ◽  
Cortical Cells ◽  
Myrica Gale ◽  
Infected Cells

Suspensions of crushed root nodules of Myrica gale containing the actinomycete Frankia induced nodule formation on roots of seedlings of M. gale and Comptonia peregrina grown in nutrient water culture. Nodules formed on M. gale were normal in structure and exhibited nitrogenase activity (measured as acetylene reduction) and provided the necessary nitrogen for seedling development. These effective nodules showed typical external and internal structure with the endophyte developing both vesicles and sporangia within cortical cells of the host tissue. Small nodules formed on C. peregrina representing the primary nodule stage. They lacked nitrogenase activity and were termed ineffective. Vesicles failed to develop within these ineffective nodules. However, sporangia were formed in infected cells and within intercellular spaces of the nodule cortical tissue. In addition, prominent amyloplasts occurred in infected cells of the ineffective nodules, a feature lacking in effective nodules. Exogenously supplied combined nitrogen increased seedling growth but did not improve nodule development or endophyte morphogenesis in the ineffective nodules.

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 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.

Use of SEM, X-ray analysis and TEM to localize Fe3+ reduction in roots

1988 ◽  
Vol 46 ◽  
pp. 392-393 ◽  
Author(s):  
William P. Wergin ◽  
P. F. Bell ◽  
Rufus L. Chaney
Keyword(s):  
Electron Microscopy ◽  
Root Hairs ◽  
Rapid Reduction ◽  
X Ray ◽  
Physical Evidence ◽  
Transmission Electron ◽  
Young Root ◽  
Insoluble Precipitate ◽  
Uptake And Transport ◽  
Scanning Electron

In dicotyledons, Fe3+ must be reduced to Fe2+ before uptake and transport of this essential macronutrient can occur. Ambler et al demonstrated that reduction along the root could be observed by the formation of a stain, Prussian blue (PB), Fe4 [Fe(CN)6]3 n H2O (where n = 14-16). This stain, which is an insoluble precipitate, forms at the reduction site when the nutrient solution contains Fe3+ and ferricyanide. In 1972, Chaney et al proposed a model which suggested that the Fe3+ reduction site occurred outside the cell membrane; however, no physical evidence to support the model was presented at that time. A more recent study using the PB stain indicates that rapid reduction of Fe3+ occurs in a region of the root containing young root hairs. Furthermore the most pronounced activity occurs in plants that are deficient in Fe. To more precisely localize the site of Fe3+ reduction, scanning electron microscopy (SEM), x-ray analysis, and transmission electron microscopy (TEM) were utilized to examine the distribution of the PB precipitate that was induced to form in roots.

Sign in / Sign up

Export Citation Format

Share Document