scholarly journals Host‐specific N od‐factors associated with M edicago truncatula nodule infection differentially induce calcium influx and calcium spiking in root hairs

2013 ◽  
Vol 200 (3) ◽  
pp. 656-662 ◽  
Author(s):  
Giulia Morieri ◽  
Eduardo A. Martinez ◽  
Andrzej Jarynowski ◽  
Hugues Driguez ◽  
Richard Morris ◽  
...  
Keyword(s):  
Calcium Influx ◽  
Root Hairs ◽  
Factors Associated ◽  
Calcium Spiking

scholarly journals Analysis of Nod-Factor-Induced Calcium Signaling in Root Hairs of Symbiotically Defective Mutants of Lotus japonicus

2006 ◽  
Vol 19 (8) ◽  
pp. 914-923 ◽  
Author(s):  
Hiroki Miwa ◽  
Jongho Sun ◽  
Giles E. D. Oldroyd ◽  
J. Allan Downie
Keyword(s):  
Calcium Influx ◽  
Lotus Japonicus ◽  
Root Hairs ◽  
Calcium Flux ◽  
Symbiotic Interaction ◽  
Nod Factor ◽  
Root Hair Deformation ◽  
Complementation Groups ◽  
Calcium Spiking ◽  
Timing Of Initiation

Nodulation (Nod)-factor signaling molecules are essential for rhizobia to initiate the nitrogen-fixing symbiotic interaction with legumes. Using a dual dye ratiometric calcium imaging technique, we have shown that 10 nM Nod factor added to roots of Lotus japonicus seedlings induces an intra-cellular calcium increase (calcium flux) that precedes oscillations in intracellular calcium (calcium spiking). The calcium flux was not observed with 1 or 0.1 nM Nod factor, which did induce calcium spiking. The calcium flux was variable in timing of initiation and duration and was observed in approximately half of the root hairs examined. Representatives from 11 complementation groups of symbiotically defective mutants were analyzed for the calcium flux. Mutants from four groups (sym6, ccamk, sym35, and nin) which retained calcium spiking all showed a normal calcium flux. Two classes of mutants (nfr1 and nfr5) lacked both calcium influx and calcium spiking, whereas five classes of mutants (symRK, castor, pollux, nup133, and sym24) defective for calcium spiking retained a calcium flux. There was no correlation between calcium spiking and induction of root hair deformation by Nod factor. We propose that increased bacterial numbers within infection foci in root hairs leads to accumulation of Nod factor to sufficient levels to activate the calcium flux, and this may drive infection thread growth.

scholarly journals Arabidopsis CNGC14 Mediates Calcium Influx Required for Tip Growth in Root Hairs

2017 ◽  
Vol 10 (7) ◽  
pp. 1004-1006 ◽  
Author(s):  
Sisi Zhang ◽  
Yajun Pan ◽  
Wang Tian ◽  
Mengqi Dong ◽  
Huifen Zhu ◽  
...  
Keyword(s):  
Tip Growth ◽  
Calcium Influx ◽  
Root Hairs

scholarly journals Analysis of Differences Between Sinorhizobium meliloti 1021 and 2011 Strains Using the Host Calcium Spiking Response

2002 ◽  
Vol 15 (12) ◽  
pp. 1245-1252 ◽  
Author(s):  
Rebecca J. Wais ◽  
Derek H. Wells ◽  
Sharon R. Long
Keyword(s):  
Gene Expression ◽  
Root Hair ◽  
Sinorhizobium Meliloti ◽  
Field Isolate ◽  
Root Hairs ◽  
Transcriptional Activators ◽  
Bacterial Gene ◽  
Nod Genes ◽  
Legume Symbiosis ◽  
Calcium Spiking

In the Rhizobium-legume symbiosis, compatible partners recognize each other through an exchange of signals. Plant inducers act together with bacterial transcriptional activators, the NodD proteins, to regulate the expression of bacterial biosynthetic nodulation (nod) genes. These genes direct the synthesis of a lipochito-oligosaccharide signal called Nod factor (NF). NFs elicit an early host response, root hair calcium spiking, that is initiated in root hair cells within 15 min of NF or live Rhizobium inoculation. We used calcium spiking as an assay to compare two closely related strains of Sinorhizobium meliloti, Rm1021 and Rm2011, derived from the same field isolate. We found that the two strains show a kinetic difference in the calcium spiking assay: Rm1021 elicits calcium spiking in host root hairs as rapidly as purified NF, whereas Rm2011 shows a significant delay. This difference can be overcome by raising expression levels of either the NodD transcriptional activators or GroEL, a molecular chaperone that affects expression of the biosynthetic nod genes. We further demonstrate that the delay in triggering calcium spiking exhibited by Rm2011 is correlated with a reduced amount of nod gene expression compared with Rm1021. Therefore, calcium spiking is a useful tool in detecting subtle differences in bacterial gene expression that affect the early stages of the Rhizobium-legume symbiosis.

scholarly journals Calcium Spiking in Plant Root Hairs Responding to Rhizobium Nodulation Signals

Cell ◽  
1996 ◽  
Vol 85 (5) ◽  
pp. 673-681 ◽  
Author(s):  
David W Ehrhardt ◽  
Rebecca Wais ◽  
Sharon R Long
Keyword(s):  
Plant Root ◽  
Root Hairs ◽  
Calcium Spiking ◽  
Rhizobium Nodulation

scholarly journals Building a hair: tip growth in Arabidopsis thaliana root hairs

2002 ◽  
Vol 357 (1422) ◽  
pp. 815-821 ◽  
Author(s):  
Rachel J. Carol ◽  
Liam Dolan
Keyword(s):  
Arabidopsis Thaliana ◽  
Reverse Genetics ◽  
Tip Growth ◽  
Fluorescent Protein ◽  
Calcium Influx ◽  
Root Hairs ◽  
New Information ◽  
Active Calcium ◽  
Green Fluorescent

The Arabidopsis thaliana root hair is used as a model for studying tip growth in plants. We review recent advances, made using physiological and genetic approaches, which give rise to different, yet compatible, current views of the establishment and maintenance of tip growth in epidermal cells. For example, an active calcium influx channel localized at the tip of Arabidopsis root hairs has been identified by patch–clamp measurements. Actin has been visualized in vivo in Arabidopsis root hairs by using a green–fluorescent–protein–talin reporter and shown to form a dense mesh in the apex of the growing tip. The kojak gene, which encodes a protein similar to the catalytic subunit of cellulose synthase, is needed in the first stages of hair growth. A role for LRX1 , a leucine–rich repeat extensin, in determining the morphology of the cell wall of root hairs has been established using reverse genetics. The new information can be integrated into a general and more advanced view of how these specialized plant cells grow.

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.

Techniques for preparing the Lolium perenne coleorhiza for scanning electron microscope evaluation

1992 ◽  
Vol 50 (1) ◽  
pp. 766-767
Author(s):  
Susan B.G. Debaene ◽  
John S. Gardner ◽  
Phil S. Allen
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Lolium Perenne ◽  
Morphological Study ◽  
Root Hairs ◽  
Inner Pressure ◽  
Water Potentials ◽  
Radicle Emergence ◽  
Standard Fixation ◽  
Scanning Electron

The coleorhiza is a nonvascular sheath that encloses the embryonic radicle in Poaceae, and is generally the first tissue to emerge during germination. Delicate hairlike extensions develop from some coleorhiza cells prior to radicle emergence. Similar to root hairs, coleorhiza hairs are extremely sensitive to desiccation and are damaged by exposure to negative water potentials. The coleorhiza of Lolium perenne is somewhat spherical when first visible, after which a knob forms at a right angle to the caryopsis due to inner pressure from the elongating radicle. This knob increases in length until the radicle finally punctures the coleorhiza. Standard fixation procedures cause severe desiccation of coleorhiza cells and hairs, making morphological study of the coleorhiza difficult. This study was conducted to determine a more successful process for coleorhiza preservation.

Stain contamination and embedding in electron microscopy

1986 ◽  
Vol 44 ◽  
pp. 50-53
Author(s):  
Hilton H. Mollenhauer
Keyword(s):  
Electron Microscopy ◽  
Information Retrieval ◽  
Epoxy Resins ◽  
Image Contrast ◽  
Sample Preservation ◽  
Factors Associated ◽  
Amount Of Information ◽  
Electron Microscopical ◽  
Contrast Information

Many factors (e.g., resolution of microscope, type of tissue, and preparation of sample) affect electron microscopical images and alter the amount of information that can be retrieved from a specimen. Of interest in this report are those factors associated with the evaluation of epoxy embedded tissues. In this context, informational retrieval is dependant, in part, on the ability to “see” sample detail (e.g., contrast) and, in part, on tue quality of sample preservation. Two aspects of this problem will be discussed: 1) epoxy resins and their effect on image contrast, information retrieval, and sample preservation; and 2) the interaction between some stains commonly used for enhancing contrast and information retrieval.

SEM and fluorescence imaging of callose deposition in root hair tips and suspension cultures of Streptanthus tortuosus

1990 ◽  
Vol 48 (3) ◽  
pp. 698-699
Author(s):  
K.S. Walters ◽  
R.D. Sjolund ◽  
K.C. Moore
Keyword(s):  
Cell Wall ◽  
Root Hair ◽  
Cultured Cells ◽  
Root Hairs ◽  
Callus Cultures ◽  
Callose Deposition ◽  
Culture Cells ◽  
Wall Structures ◽  
Ultraviolet Illumination ◽  
Callose Formation

Callose, B-1,3-glucan, a component of cell walls, is associated with phloem sieve plates, plasmodesmata, and other cell wall structures that are formed in response to wounding or infection. Callose reacts with aniline blue to form a fluorescent complex that can be recognized in the light microscope with ultraviolet illumination. We have identified callose in cell wall protuberances that are formed spontaneously in suspension-cultured cells of S. tortuosus and in the tips of root hairs formed in sterile callus cultures of S. tortuosus. Callose deposits in root hairs are restricted to root hair tips which appear to be damaged or deformed, while normal root hair tips lack callose deposits. The callose deposits found in suspension culture cells are restricted to regions where unusual outgrowths or protuberances are formed on the cell surfaces, specifically regions that are the sites of new cell wall formation.Callose formation has been shown to be regulated by intracellular calcium levels.

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