Relationship of autofluorescent and ultraviolet-absorbing components in cell walls and wall appositions to disease resistance in kohlrabi roots

1986 ◽  
Vol 64 (2) ◽  
pp. 273-275 ◽  
Author(s):  
James R. Aist ◽  
Herbert W. Israel
Keyword(s):  
Cell Walls ◽  
Secondary Wall ◽  
Root Hairs ◽  
Root Hair Cell ◽  
Vessel Elements ◽  
Wall Appositions ◽  
Olpidium Brassicae ◽  
Phenolic Derivatives ◽  
Relationship Of ◽  
Resistance To Penetration

It has been shown that wound plugs induced mechanically by bending of kohlrabi root hairs are more resistant to subsequent penetration attempts by Olpidium brassicae than are papillae induced by the fungus. A histochemical, autofluorescence, and ultraviolet-microspectrophotometric study was undertaken to determine if a differential composition of phenolic derivatives could explain this difference in resistance. Phenolics in the secondary wall thickenings of xylem vessel elements of roots were distinct from those in wound plugs, papillae, and root hair cell walls. But phenolics in wound plugs and papillae could not be distinguished from each other by the methods employed. Thus, the results do not support the hypothesis that wound plugs are more resistant to penetration than are papillae because they contain phenolic derivatives not found in the latter. However, the possibility that an earlier deposition of phenolics in wound plugs accounts for their greater resistance to penetration has not been ruled out.

Autofluorescent and ultraviolet-absorbing components in cell walls and papillae of barley coleoptiles and their relationship to disease resistance

1986 ◽  
Vol 64 (2) ◽  
pp. 266-272 ◽  
Author(s):  
James R. Aist ◽  
Herbert W. Israel
Keyword(s):  
Disease Resistance ◽  
Cell Walls ◽  
Secondary Wall ◽  
Epidermal Cells ◽  
Ultraviolet Absorption ◽  
Absorption Properties ◽  
Vessel Elements ◽  
Histochemical Tests ◽  
Phenolic Derivatives ◽  
Periclinal Walls

Earlier studies showed that normal-size papillae induced in barley coleoptile epidermal cells by Erysiphe graminis f. sp. hordei were less effective in resisting fungal penetration attempts than were oversize papillae. To determine if a differential content of phenolic derivatives could account for this difference in resistance, we analyzed normal papillae and oversize papillae by histochemical, epifluorimetric, and ultraviolet-microspectrophotometric methods. Whereas the histochemical tests revealed phenolic derivatives only in oversize papillae, the autofluorescence and ultraviolet-absorption properties indicated that both types of papillae contain phenolics. Ultraviolet-absorption spectra indicated that the phenolics were primarily phenylpropanoid groups. Phenolics in papillae were distinct from both those in the secondary wall thickenings of coleoptile xylem vessel elements and those in the periclinal walls of coleoptile epidermal cells. The deposition of phenolics in oversize papillae long before they were challenged by the fungus, the presence of certain phenolics that, tentatively, were detected histochemically only in the oversize papillae, or both could have rendered them resistant to penetration by the fungus.

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 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.

Cytochemical localization of peroxidase activity in wound vessel members of Coleus

1972 ◽  
Vol 50 (5) ◽  
pp. 977-983 ◽  
Author(s):  
Peter K. Hepler ◽  
Rita M. Rice ◽  
William A. Terranova
Keyword(s):  
Peroxidase Activity ◽  
Cell Walls ◽  
Secondary Wall ◽  
Primary Wall ◽  
Electron Microscopic ◽  
Cytochemical Localization ◽  
Secondary Thickening ◽  
Vessel Elements ◽  
Microscopic Investigations

Peroxidase activity has been localized in the cell walls and cytoplasm of wound vessel elements of Coleus which had been fixed in glutaraldehyde, incubated in diaminobenzidine (DAB) and H2O2, and postfixed in OSO4. Electron microscopic investigations revealed prominent staining in the reticulate secondary wall and in the primary wall where the secondary thickenings attach. The stain in the secondary wall is finely textured and heavier towards its periphery than towards its core. The staining of the primary wall, however, is coarsely granular. In the cytoplasm of differentiating vessel elements electron-opaque deposits are observed in the plasmalemma, especially where it overlies the secondary thickening, and in the dictyosomes and their associated vesicles. Staining also occurs on the internal membranes of developing chloroplasts where it is most likely the result of photooxidation of DAB.Staining, except in chloroplasts, appears to be due specifically to peroxidase, since either removal of H2O2 or preincubation with KCN markedly reduces staining, whereas preincubation with aminotriazole, an inhibitor of catalase, does not. The similarity of localization of peroxidase and lignin in the walls of Coleus wound vessel elements supports the postulate that the enzyme participates in lignification.

scholarly journals Involvement of CesA4, CesA7-A/B and CesA8-A/B in secondary wall formation in Populus trichocarpa wood

2019 ◽  
Vol 40 (1) ◽  
pp. 73-89 ◽  
Author(s):  
Manzar Abbas ◽  
Ilona Peszlen ◽  
Rui Shi ◽  
Hoon Kim ◽  
Rui Katahira ◽  
...  
Keyword(s):  
Solid State ◽  
Mechanical Strength ◽  
Cell Walls ◽  
Secondary Wall ◽  
Populus Trichocarpa ◽  
Wood Formation ◽  
Fiber Cell ◽  
Modulus Of Rupture ◽  
Cellulose Content ◽  
Wall Formation

Abstract Cellulose synthase A genes (CesAs) are responsible for cellulose biosynthesis in plant cell walls. In this study, functions of secondary wall cellulose synthases PtrCesA4, PtrCesA7-A/B and PtrCesA8-A/B were characterized during wood formation in Populus trichocarpa (Torr. & Gray). CesA RNAi knockdown transgenic plants exhibited stunted growth, narrow leaves, early necrosis, reduced stature, collapsed vessels, thinner fiber cell walls and extended fiber lumen diameters. In the RNAi knockdown transgenics, stems exhibited reduced mechanical strength, with reduced modulus of rupture (MOR) and modulus of elasticity (MOE). The reduced mechanical strength may be due to thinner fiber cell walls. Vessels in the xylem of the transgenics were collapsed, indicating that water transport in xylem may be affected and thus causing early necrosis in leaves. A dramatic decrease in cellulose content was observed in the RNAi knockdown transgenics. Compared with wildtype, the cellulose content was significantly decreased in the PtrCesA4, PtrCesA7 and PtrCesA8 RNAi knockdown transgenics. As a result, lignin and xylem contents were proportionally increased. The wood composition changes were confirmed by solid-state NMR, two-dimensional solution-state NMR and sum-frequency-generation vibration (SFG) analyses. Both solid-state nuclear magnetic resonance (NMR) and SFG analyses demonstrated that knockdown of PtrCesAs did not affect cellulose crystallinity index. Our results provided the evidence for the involvement of PtrCesA4, PtrCesA7-A/B and PtrCesA8-A/B in secondary cell wall formation in wood and demonstrated the pleiotropic effects of their perturbations on wood formation.

scholarly journals The TOR–Auxin Connection Upstream of Root Hair Growth

Plants ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 150 ◽  
Author(s):  
Katarzyna Retzer ◽  
Wolfram Weckwerth
Keyword(s):  
Cell Fate ◽  
Root Hair ◽  
Hair Growth ◽  
Environmental Changes ◽  
Growth Control ◽  
Root Hairs ◽  
Signaling Cascades ◽  
Continuous Growth ◽  
Root Hair Cell ◽  
Root Hair Growth

Plant growth and productivity are orchestrated by a network of signaling cascades involved in balancing responses to perceived environmental changes with resource availability. Vascular plants are divided into the shoot, an aboveground organ where sugar is synthesized, and the underground located root. Continuous growth requires the generation of energy in the form of carbohydrates in the leaves upon photosynthesis and uptake of nutrients and water through root hairs. Root hair outgrowth depends on the overall condition of the plant and its energy level must be high enough to maintain root growth. TARGET OF RAPAMYCIN (TOR)-mediated signaling cascades serve as a hub to evaluate which resources are needed to respond to external stimuli and which are available to maintain proper plant adaptation. Root hair growth further requires appropriate distribution of the phytohormone auxin, which primes root hair cell fate and triggers root hair elongation. Auxin is transported in an active, directed manner by a plasma membrane located carrier. The auxin efflux carrier PIN-FORMED 2 is necessary to transport auxin to root hair cells, followed by subcellular rearrangements involved in root hair outgrowth. This review presents an overview of events upstream and downstream of PIN2 action, which are involved in root hair growth control.

Phenological Comparison of the Onset of Vessel Formation Between Ring-Porous and Diffuse-Porous Deciduous Trees in a Japanese Temperate Forest

IAWA Journal ◽  
1996 ◽  
Vol 17 (4) ◽  
pp. 431-444 ◽  
Author(s):  
Mitsuo Suzuki ◽  
Kiyotsugu Yoda ◽  
Hitoshi Suzuki
Keyword(s):  
Secondary Wall ◽  
Leaf Expansion ◽  
Vessel Element ◽  
Early Maturation ◽  
Vessel Formation ◽  
Wall Deposition ◽  
Water Conduction ◽  
Vessel Elements ◽  
Secondary Wall Deposition ◽  
Diffuse Porous

Initiation of vessel formation and vessel maturation indicated by secondary wall deposition have been compared in eleven deciduous broadleaved tree species. In ring-porous species the first vessel element formation in the current growth ring was initiated two to six weeks prior to the onset of leaf expansion, and secondary wall deposition on the vessel elements was completed from one week before to three weeks after leaf expansion. In diffuse-porous species, the first vessel element formation was initiated two to seven weeks after the onset of leaf expansion, and secondary wall deposition was completed four to nine weeks after leaf expansion. These results suggest that early maturation of the first vessel elements in the ring-porous species will serve for water conduction in early spring. On the contrary, the late maturation of the first vessel elements in the diffuse-porous species indicates that no new functional vessels exist at the time of the leaf expansion.

Review — The Orientation of Cellulose Microfibrils in the cell walls of Tracheids in Conifers

IAWA Journal ◽  
2005 ◽  
Vol 26 (2) ◽  
pp. 161-174 ◽  
Author(s):  
Hisashi Abe ◽  
Ryo Funada
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Outer Layer ◽  
Cell Walls ◽  
Secondary Wall ◽  
Middle Layer ◽  
Cellulose Microfibrils ◽  
Conifer Species ◽  
Predominant Orientation ◽  
Scanning Electron

We examined the orientation of cellulose microfibrils (Mfs) in the cell walls of tracheids in some conifer species by field emission-scanning electron microscopy (FE-SEM) and developed a model on the basis of our observations. Mfs depositing on the primary walls in differentiating tracheids were not well-ordered. The predominant orientation of the Mfs changed from longitudinal to transverse, as the differentiation of tracheids proceeded. The first Mfs to be deposited in the outer layer of the secondary wall (S1 layer) were arranged as an S-helix. Then the orientation of Mfs changed gradually, with rotation in the clockwise direction as viewed from the lumen side of tracheids, from the outermost to the innermost S1 layer. Mfs in the middle layer of the secondary wall (S2 layer) were oriented in a steep Z-helix with a deviation of less than 15° within the layer. The orientation of Mfs in the inner layer of the secondary wall (S3 layer) changed, with rotation in a counterclockwise direction as viewed from the lumen side, from the outermost to the innermost S3 layer. The angle of orientation of Mfs that were deposited on the innermost S3 layer varied among tracheids from 40° in a Z-helix to 20° in an S-helix.

Resistance of hardwood vessels to degradation by white rot Basidiomycetes

1988 ◽  
Vol 66 (9) ◽  
pp. 1841-1847 ◽  
Author(s):  
Robert A. Blanchette ◽  
John R. Obst ◽  
John I. Hedges ◽  
Karen Weliky
Keyword(s):  
Cell Wall ◽  
Secondary Wall ◽  
White Rot ◽  
Fungal Decay ◽  
Acacia Koa ◽  
Monomer Composition ◽  
Lignin Removal ◽  
Vessel Elements ◽  
Parenchyma Cells ◽  
Unusual Type

White stringy rot, an unusual type of selective fungal decay, can be found in wood of some dicotyledonous angiosperms. Stages of advanced decay consist of a mass of vessel elements with only remnants of other cells adhering to the vessel walls. Degradation by various white rot Basidiomycetes causes loss of fibers, fiber tracheids, and parenchyma cells but not vessels. In wood of Acacia koa var. koa with a white pocket rot caused by Phellinus kawakamii, fibers and parenchyma cells were preferentially delignified. After extensive lignin removal the cellulose remaining in the secondary wall was degraded. Large vessel elements remained relatively intact after other cells were completely degraded. The resistance of vessels to degradation appears to be due to their high ligninxarbohydrate ratio, lignin monomer composition, and cell wall morphology.

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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