scholarly journals Rapid, Plateau-like Increases in Intracellular Free Calcium Are Associated with Nod-Factor—Induced Root-Hair Deformation

1997 ◽  
Vol 10 (7) ◽  
pp. 791-802 ◽  
Author(s):  
Christoph A. Gehring ◽  
Helen R. Irving ◽  
Akram A. Kabbara ◽  
Roger W. Parish ◽  
Nawal M. Boukli ◽  
...  
Keyword(s):  
Root Hair ◽  
Root Hairs ◽  
Epidermal Cells ◽  
Intracellular Free Calcium ◽  
Free Calcium ◽  
Broad Host Range ◽  
Nod Factors ◽  
Root Cortex ◽  
Cellular Events ◽  
Root Hair Deformation

Rhizobia excrete variously substituted lipo-oligosaccha-ride Nod factors into the legume rhizosphere. Homologous legumes respond to these signals through deformation of the root hairs and the development of nodulation foci in the root cortex. Cellular events in root hairs from the susceptible zone of nearly mature root hairs were studied in root segments loaded with the calcium indicators Fura-2 or Fluo-3. Application of 10-9 M Nod factors of the broad-host-range Rhizobium sp. NGR234 to the homologous legume Vigna unguiculata resulted, within seconds, in plateau-like increases in intracellular free calcium ([Ca2+]i) in the root hairs and root epidermal cells. Nod factors of R. meliloti at 10-9 M caused equally rapid increases in [Ca2+]i in the root hairs and epidermal cells of the nonhost V. unguiculata, and also induced root-hair deformation. The chitin tetramer, N-N′-N″-N′″-tetracetylchitotetraose, which represents the backbone of Nod factors, induced neither root-hair deformation nor changes in [Ca2+]i in V. unguiculata. Root hairs and epidermal cells of the nonlegume non-host Arabidopsis thaliana showed neither [Ca2+]i increases nor root-hair deformation in response to both factors.

scholarly journals Identical Accumulation and Immobilization of Sulfated and Nonsulfated Nod Factors in Host and Nonhost Root Hair Cell Walls

2003 ◽  
Vol 16 (10) ◽  
pp. 884-892 ◽  
Author(s):  
Joachim Goedhart ◽  
Jean-Jacques Bono ◽  
Ton Bisseling ◽  
Theodorus W. J. Gadella
Keyword(s):  
Hair Cell ◽  
Root Hair ◽  
Cell Walls ◽  
Root Hairs ◽  
Sharp Decrease ◽  
Biologically Active ◽  
Nod Factors ◽  
Nod Factor ◽  
Root Hair Cell ◽  
Root Hair Deformation

Nod factors are signaling molecules secreted by Rhizobium bacteria. These lipo-chitooligosaccharides (LCOs) are required for symbiosis with legumes and can elicit specific responses at subnanomolar concentrations on a compatible host. How plants perceive LCOs is unclear. In this study, using fluorescent Nod factor analogs, we investigated whether sulfated and nonsulfated Nod factors were bound and perceived differently by Medicago truncatula and Vicia sativa root hairs. The bioactivity of three novel sulfated fluorescent LCOs was tested in a root hair deformation assay on M. truncatula, showing bioactivity down to 0.1 to 1 nM. Fluorescence microscopy of plasmolyzed M. truncatula root hairs shows that sulfated fluorescent Nod factors accumulate in the cell wall of root hairs, whereas they are absent from the plasma membrane when applied at 10 nM. When the fluorescent Nod factor distribution in medium surrounding a root was studied, a sharp decrease in fluorescence close to the root hairs was observed, visualizing the remarkable capacity of root hairs to absorb Nod factors from the medium. Fluorescence correlation microscopy was used to study in detail the mobilities of sulfated and nonsulfated fluorescent Nod factors which are biologically active on M. truncatula and V. sativa, respectively. Remarkably, no difference between sulfated and nonsulfated Nod factors was observed: both hardly diffuse and strongly accumulate in root hair cell walls of both M. truncatula and V. sativa. The implications for the mode of Nod factor perception are discussed.

scholarly journals Rhizobium Nod factors induce increases in intracellular free calcium and extracellular calcium influxes in bean root hairs

1999 ◽  
Vol 19 (3) ◽  
pp. 347-352 ◽  
Author(s):  
Luis Cardenas ◽  
Jose A. Feijo ◽  
Joseph G. Kunkel ◽  
Federico Sanchez ◽  
Terena Holdaway-Clarke ◽  
...  
Keyword(s):  
Root Hairs ◽  
Extracellular Calcium ◽  
Intracellular Free Calcium ◽  
Free Calcium ◽  
Nod Factors ◽  
Bean Root

scholarly journals Invasion by Invitation: Rhizobial Infection in Legumes

2011 ◽  
Vol 24 (6) ◽  
pp. 631-639 ◽  
Author(s):  
Jeremy D. Murray
Keyword(s):  
Root Hair ◽  
Root Hairs ◽  
Infection Process ◽  
Nodule Development ◽  
Nod Factors ◽  
Cortical Cells ◽  
Root Cortex ◽  
Root Hair Cell ◽  
Cytoplasmic Bridges ◽  
Cytoskeletal Rearrangements

Nodulation of legume roots typically begins with rhizobia attaching to the tip of a growing root-hair cell. The attached rhizobia secrete Nod factors (NF), which are perceived by the plant. This initiates a series of preinfection events that include cytoskeletal rearrangements, curling at the root-hair tip, and formation of radially aligned cytoplasmic bridges called preinfection threads (PIT) in outer cortical cells. Within the root-hair curl, an infection pocket filled with bacteria forms, from which originates a tubular invagination of cell wall and membrane called an infection thread (IT). IT formation is coordinated with nodule development in the underlying root cortex tissues. The IT extends from the infection pocket down through the root hair and into the root cortex, where it passes through PIT and eventually reaches the nascent nodule. As the IT grows, it is colonized by rhizobia that are eventually released into cells within the nodule, where they fix nitrogen. NF can also induce cortical root hairs that appear to originate from PIT and can become infected like normal root hairs. Several genes involved in NF signaling and some of the downstream transcription factors required for infection have been characterized. More recently, several genes with direct roles in infection have been identified, some with roles in actin rearrangement and others with possible roles in protein turnover and secretion. This article provides an overview of the infection process, including the roles of NF signaling, actin, and calcium and the influence of the hormones ethylene and cytokinin.

Root hair deformation in the infection process of Alnus rubra

1983 ◽  
Vol 61 (11) ◽  
pp. 2863-2876 ◽  
Author(s):  
Alison M. Berry ◽  
John G. Torrey
Keyword(s):  
Root Hair ◽  
Cell Walls ◽  
Root Hairs ◽  
Infection Process ◽  
Alnus Rubra ◽  
Pseudomonas Cepacia ◽  
Developmental Studies ◽  
Experimental Conditions ◽  
Root Hair Cell ◽  
Root Hair Deformation

Structural and cell developmental studies of root hair deformation in Alnus rubra Bong. (Betulaceae) were carried out following inoculation with the soil pseudomonad Pseudomonas cepacia 85, alone or in concert with Frankia, and using axenically grown seedlings. Deformational changes can be observed in elongating root hairs within 2 h of inoculation with P. cepacia 85. These growing root hairs become branched or multilobed and highly modified from the single-tip growth of axenic root hairs. The cell walls of deformed hairs are histologically distinctive when stained with the fluorochrome acridine orange. Filtrate studies using P. cepacia 85 suggest that the deforming substance is not a low molecular weight compound. Root hair deformation and the associated wall histology are host specific in that Betula root hairs show none of these responses when grown and inoculated in the experimental conditions described. The bacterially induced changes in root hair cell walls during deformation may create a chemically and physically modified substrate for Frankia penetration, and the deformation itself may serve to entrap and enclose the filamentous organism, allowing wall dissolution and entry. Thus these events represent a complex host response as a precondition to successful nodulation.

scholarly journals Analysis of Promoter Activity of the Early Nodulin Enod40 in Lotus japonicus

2005 ◽  
Vol 18 (5) ◽  
pp. 414-427 ◽  
Author(s):  
Mette Grønlund ◽  
Andreas Roussis ◽  
Emmanouil Flemetakis ◽  
Nicolette E. M. Quaedvlieg ◽  
Helmi R. M. Schlaman ◽  
...  
Keyword(s):  
Promoter Activity ◽  
Lotus Japonicus ◽  
Root Hairs ◽  
Early Time ◽  
Cellular Level ◽  
Nod Factors ◽  
Root Cortex ◽  
Model Legume ◽  
Early Nodulin ◽  
Nodulin Genes

Our comparative studies on the promoter (pr) activity of Enod40 in the model legume Lotus japonicus in stably transformed GusA reporter lines and in hairy roots of L. japonicus demonstrate a stringent regulation of the Enod40 promoter in the root cortex and root hairs in response to Nod factors. Interestingly, the L. japonicus Enod40-2 promoter fragment also shows symbiotic activity in the reverse orientation. Deletion analyses of the Glycine max (Gm) Enod40 promoter revealed the presence of a minimal region -185 bp upstream of the transcription start. Stable transgenic L. japonicus reporter lines were used in bioassays to test the effect of different compounds on early symbiotic signaling. The responses of prGmEnod40 reporter lines were compared with the responses of L. japonicus (Lj) reporter lines based on the LjNin promoter. Both reporter lines show very early activity postinoculation in root hairs of the responsive zone of the root and later in the dividing cells of nodule primordia. The LjNin promoter was found to be more responsive than the GmEnod40 promoter to Nod factors and related compounds. The use of prGmEnod40 reporter lines to analyze the effect of nodulin genes on the GmEnod40 promoter activity indicates that LJNIN has a positive effect on the regulation of the Enod40 promoter, whereas the latter is not influenced by ectopic overexpression of its own gene product. In addition to pointing to a difference in the regulation of the two nodulin genes Enod40 and Nin during early time points of symbiosis, the bioassays revealed a difference in the response to the synthetic cytokinin 6-benzylaminopurine (BAP) between alfalfa and clover and L. japonicus. In alfalfa and clover, Enod40 expression was induced upon BAP treatment, whereas this seems not to be the case in L. japonicus; these results correlate with effects at the cellular level because BAP can induce pseudonodules in alfalfa and clover but not in L. japonicus. In conclusion, we demonstrate the applicability of the described L. japonicus reporter lines in analyses of the specificity of compounds related to nodulation as well as for the dissection of the interplay between different nodulin genes.

scholarly journals The Small GTPase ROP10 of Medicago truncatula Is Required for Both Tip Growth of Root Hairs and Nod Factor-Induced Root Hair Deformation

2015 ◽  
Vol 27 (3) ◽  
pp. 806-822 ◽  
Author(s):  
Ming-Juan Lei ◽  
Qi Wang ◽  
Xiaolin Li ◽  
Aimin Chen ◽  
Li Luo ◽  
...  
Keyword(s):  
Medicago Truncatula ◽  
Root Hair ◽  
Tip Growth ◽  
Root Hairs ◽  
Small Gtpase ◽  
Nod Factor ◽  
Root Hair Deformation

The homeobox gene GLABRA2 is required for position-dependent cell differentiation in the root epidermis of Arabidopsis thaliana

Development ◽  
1996 ◽  
Vol 122 (4) ◽  
pp. 1253-1260 ◽  
Author(s):  
J.D. Masucci ◽  
W.G. Rerie ◽  
D.R. Foreman ◽  
M. Zhang ◽  
M.E. Galway ◽  
...  
Keyword(s):  
Epidermal Cell ◽  
Hair Cells ◽  
Root Hair ◽  
Root Hairs ◽  
Homeobox Gene ◽  
Epidermal Cells ◽  
Wild Type ◽  
Cell Identity ◽  
Root Epidermis ◽  
Root Hair Cells

The role of the Arabidopsis homeobox gene, GLABRA 2 (GL2), in the development of the root epidermis has been investigated. The wild-type epidermis is composed of two cell types, root-hair cells and hairless cells, which are located at distinct positions within the root, implying that positional cues control cell-type differentiation. During the development of the root epidermis, the differentiating root-hair cells (trichoblasts) and the differentiating hairless cells (atrichoblasts) can be distinguished by their cytoplasmic density, vacuole formation, and extent of elongation. We have determined that mutations in the GL2 gene specifically alter the differentiation of the hairless epidermal cells, causing them to produce root hairs, which indicates that GL2 affects epidermal cell identity. Detailed analyses of these differentiating cells showed that, despite forming root hairs, they are similar to atrichoblasts of the wild type in their cytoplasmic characteristics, timing of vacuolation, and extent of cell elongation. The results of in situ nucleic acid hybridization and GUS reporter gene fusion studies show that the GL2 gene is preferentially expressed in the differentiating hairless cells of the wild type, during a period in which epidermal cell identity is believed to be established. These results indicate that the GL2 homeodomain protein normally regulates a subset of the processes that occur during the differentiation of hairless epidermal cells of the Arabidopsis root. Specifically, GL2 appears to act in a cell-position-dependent manner to suppress hair formation in differentiating hairless cells.

Nod factors modulate the concentration of cytosolic free calcium differently in growing and non-growing root hairs of Medicago sativa L.

Planta ◽  
1999 ◽  
Vol 209 (2) ◽  
pp. 207-212 ◽  
Author(s):  
Hubert H. Felle ◽  
Éva Kondorosi ◽  
ÁdÁm Kondorosi ◽  
Michael Schultze
Keyword(s):  
Medicago Sativa ◽  
Root Hairs ◽  
Free Calcium ◽  
Nod Factors ◽  
Cytosolic Free Calcium ◽  
Medicago Sativa L

ROP6 is involved in root hair deformation induced by Nod factors in Lotus japonicus

2016 ◽  
Vol 108 ◽  
pp. 488-498 ◽  
Author(s):  
Danxia Ke ◽  
Xiangyong Li ◽  
Yapeng Han ◽  
Lin Cheng ◽  
Hongyu Yuan ◽  
...  
Keyword(s):  
Root Hair ◽  
Lotus Japonicus ◽  
Nod Factors ◽  
Root Hair Deformation

scholarly journals Rhizobia Modulate Root-Hair-Specific Expression of Extensin Genes

1997 ◽  
Vol 10 (1) ◽  
pp. 95-101 ◽  
Author(s):  
Ivana Arsenijevic-Maksimovic ◽  
William J. Broughton ◽  
Andrea Krause
Keyword(s):  
Root Hair ◽  
Promoter Region ◽  
Root Hairs ◽  
Mrna Levels ◽  
Genomic Locus ◽  
Gene Encoding ◽  
Specific Expression ◽  
Transcript Levels ◽  
Root Hair Deformation ◽  
Lectin Promoter

Three cDNAs (ext3, ext127, and ext26), originally isolated by differential screening from a root-hair cDNA library of Vigna unguiculata, were found to encode extensin-like cell wall proteins. Transcripts homologous to these cDNAs were only detected in root hairs where mRNA levels decreased 1 day after inoculation with rhizobia. This coincided with the onset of root-hair deformation, the first morphological step in the Rhizobium-legume interaction. Decreases in transcript levels following inoculation with wild-type Rhizobium sp. NGR234 were more pronounced than with NGRΔnodABC, a mutant deficient in Nod-factor production. Inoculation with a rhizobial strain carrying a mutation in a gene encoding a transcriptional activator for nod genes (NGRΔnodD1) did not repress mRNA levels, indicating that a second nodulation signal may be present that is nodD dependent. Application of purified NodNGR factors only affected transcript levels of ext3. The genomic locus of the gene homologous to ext26 (Ext26G) was cloned. In the 5′ flanking region, several potential TATA boxes and CAP signals were identified. Part of the promoter region shares homology with the Pisum sativum seed lectin promoter and the Nicotiana tabacum nitrate reductase promoter region. Nonetheless, the function of these homologous regions in gene regulation is unknown.

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