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.

Cytological and histochemical characteristics of the axenic root surface of Alnus glutinosa

1986 ◽  
Vol 64 (10) ◽  
pp. 2216-2226 ◽  
Author(s):  
Yves Prin ◽  
Mireille Rougier
Keyword(s):  
Cell Wall ◽  
Root Hair ◽  
Root Hairs ◽  
Root Apex ◽  
Alnus Glutinosa ◽  
Root Surface ◽  
Infection Process ◽  
Root Cap ◽  
A Cell ◽  
Histochemical Tests

The aim of the present study was to investigate the Alnus root surface using seedlings grown axenically. This study has focused on root zones where infection by the symbiotic actinomycete Frankia takes place. The zones examined extend from the root cap to the emerging root hair zone. The root cap ensheaths the Alnus root apex and extends over the root surface as a layer of highly flattened cells closely appressed to the root epidermal cell wall. These cells contain phenolic compounds as demonstrated by various histochemical tests. They are externally bordered by a thin cell wall coated by a thin mucilage layer. The root cap is ruptured when underlying epidermal cells elongate, and cell remnants are still found in the emerging root hair zone. Young emerging root hairs are bordered externally by a cell wall covered by a thin mucilage layer which reacts positively to the tests used for the detection of polysaccharides, glycoproteins, and anionic sites. The characteristics of the Alnus root surface and the biological function of mucilage and phenols present at the root surface are discussed in relation to the infection process.

Cell wall texture in root hairs of the genus Equisetum

1986 ◽  
Vol 64 (10) ◽  
pp. 2201-2206 ◽  
Author(s):  
Anne Mie C. Emons
Keyword(s):  
Cell Wall ◽  
Root Hair ◽  
Root Hairs ◽  
Wall Layer ◽  
Cell Wall Layer ◽  
Additional Layer ◽  
Cell Wall Texture ◽  
Helicoidal Texture

Based on cell wall texture of root hairs, two groups can be distinguished within the 10 species of Equisetum listed in Flora Europaea. This distinction coincides with the division of the genus Equisetum into two subgenera: Equisetum (horsetails) and Hippochaete (scouring rushes). All species of the subgenus Equisetum have a helicoidal cell wall texture in young growing root hairs as well as in full-grown hairs. All species of the subgenus Hippochaete deposit an additional inner cell wall layer against this helicoidal layer when elongation has stopped. The microfibrils in this additional layer do not form a helicoidal texture, but are helically arranged, forming a Z-helix. The presence of a helical layer in full-grown hairs is not a prerequisite for growth in soil, but an exclusively helicoidal root hair wall texture might be favourable for life in water. The wall texture is not influenced by the consistency of the substratum.

Root hair cell walls: filling in the frameworkThis review is one of a selection of papers published in the Special Issue on Plant Cell Biology.

2006 ◽  
Vol 84 (4) ◽  
pp. 613-621 ◽  
Author(s):  
M.E. Galway
Keyword(s):  
Cell Wall ◽  
Hair Cell ◽  
Plant Cell ◽  
Root Hair ◽  
Cell Walls ◽  
Cell Biology ◽  
High Speed ◽  
Root Hairs ◽  
Experimental System ◽  
Plant Cell Walls

Rapid progress is being made in determining the composition, synthesis, and mechanical properties of plant cell walls. Although tip-growing root hairs provide an excellent example of high-speed cell wall assembly, they have been relatively neglected by researchers interested in cell walls and those interested in tip growth. This review aims to present the root hair as an experimental system for future cell wall studies by assembling recent discoveries about the walls onto the existing framework based on older information. Most recent data come from arabidopsis ( Arabidopsis thaliana (L.) Heynh) and model legumes. Evidence supporting the turgor-mediated expansion of hair cell walls is considered, along with a survey of three components needed for cell wall expansion without rupture: cellulose (the role of CesA cellulose synthases is also addressed), Csld3, a cellulose synthase-like protein, and Lrx1, a cell wall protein. Further clues about hair cell wall composition have been obtained from gene expression studies and the use of monoclonal antibodies. Finally, there is a review of the experimental evidence that (i) hairs near the hypocotyl differ developmentally and structurally from other hairs and (ii) biosynthesis of wall components in hairs may differ significantly from the epidermal cells that they grew from. All of these recent advances suggest that root hairs could provide valuable data to augment models of plant cell walls based on more conventional cell types.

Helicoidal microfibril deposition in a tip-growing cell and microtubule alignment during tip morphogenesis: a dry-cleaving and freeze-substitution study

1989 ◽  
Vol 67 (8) ◽  
pp. 2401-2408 ◽  
Author(s):  
Anne Mie C. Emons
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Root Hair ◽  
Root Hairs ◽  
Freeze Substitution ◽  
Axial Direction ◽  
Microfibril Orientation ◽  
Growing Cell ◽  
Equisetum Hyemale ◽  
Dry Cleaving

Cell wall microfibril alignment in the tubular portion of Equisetum hyemale root hairs is helicoidal. Lamellae of helicoidal texture are deposited from tip to base; thus, different microfibril orientations are aligned with the plasma membrane successively. Zones with constant mean microfibril orientation are about 300 μm long. In any such zone of dry-cleaned, shadowed preparations, the frequency of microfibrils at the proximal end is 5 to 7 microfibrils per micrometre, which decreases to 0 at the distal end. The orientation of microfibrils of the underlying lamella, the microfibril frequency of which is 5 to 7/μm throughout, is the same as the microfibril orientation of the neighbouring distal lamella. Microfibrils of the cell wall are randomly oriented in the hair dome. Microtubule alignment in these root hairs was examined by means of freeze substitution. In the extreme tip of the root hair, microtubules run parallel to the plasma membrane and transverse to the long axis of the hair; the hemisphere of the hair contains randomly oriented microtubules. From extreme tip to base of the hair dome, microtubules become more and more axially aligned, and remain axially oriented in the hair tube. Further down the hair, where microfibril alignment is transverse and microfibrils are actively being deposited, microtubules still run in the axial direction. The observations emphasize the involvement of microtubles in root hair tip morphogenesis, but not in determining the alignment of the microfibrils in the hair tube.

STUDIES ON THE LIFE HISTORY OF THE CLUB ROOT ORGANISM, PLASMODIOPHORA BRASSICAE

1944 ◽  
Vol 22c (4) ◽  
pp. 143-149 ◽  
Author(s):  
G. W. Ayers
Keyword(s):  
Cell Wall ◽  
Root Hair ◽  
Plasmodiophora Brassicae ◽  
Tap Water ◽  
Root Hairs ◽  
Average Diameter ◽  
Root Cells ◽  
Free Moisture ◽  
History Of ◽  
Bacteria And Fungi

In the present studies on Plasmodiophora Brassicae Wor., attention was focussed principally on the development of the zoosporangium and the formation and discharge of the zoospores.Resting spores, released from thoroughly clubbed tissue by the action of bacteria and fungi, germinated well in tap water at room temperature in 1 to 10 days. Germination was hastened by exposure to frost.The zoospores from the resting spores are biflagellate and heterokont, and vary in size. When such a zoospore comes in contact with root hairs or epidermal root cells of cruciferous seedlings, it settles down as an amoeba and penetrates the cell wall to form a young thallus within the host cell. The thallus may or may not become considerably enlarged before the protoplasm undergoes cleavage and an irregular cluster of zoosporangia is formed. Each zoosporangium contains four to eight zoospores, which, at maturity, are discharged from the root hair if free moisture is present; otherwise the fungal protoplasm disintegrates. At ordinary field temperatures, from four to six days are required from infection of the host to the discharge of zoospores from the zoosporangium. Discharge takes place through small openings at the point of contact of the zoosporangia with the cell wall of the root hair. These zoospores when discharged are not more than one-half the average diameter of the zoospores from germinating resting spores.Controlled temperature, studies have shown that temperatures most favourable for the growth of the host are also most favourable for infection. The optimum temperature for infection was about 70° F., the minimum between 54° and 57° F., and the maximum above 92° F. Only two to two and one-half days were needed for the process.

scholarly journals The SYP123-VAMP727 SNARE complex is involved in the delivery of inner cell wall components to the root hair shank in Arabidopsis

2020 ◽  
Author(s):  
Tomoko Hirano ◽  
Kazuo Ebine ◽  
Takashi Ueda ◽  
Takumi Higaki ◽  
Takahiro Nakayama ◽  
...  
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Root Hair ◽  
Cortical Microtubule ◽  
Root Hairs ◽  
Snare Complex ◽  
Cell Wall Components ◽  
Root Hair Cell ◽  
Wall Stiffness ◽  
Wall Components

AbstractA root hair is a long tubular protrusion from a root hair cell established via tip growth, which is accomplished by the polarized deposition of membranous and cell wall components at the root hair apex accompanied by simultaneous hardening of the shank. The polarized secretion of materials to the root hair apex is well investigated; however, little is known about the deposition of inner cell wall materials at the root hair shank. We have previously reported that phosphatidylinositol-3,5-bisphosphate (PtdIns(3,5)P2)/ROP10 signaling is required for the regulation of cortical microtubule construction and the deposition of inner cell wall components at the root hair shank during hardening. To unravel the alternate secretion mechanism for delivery of the inner cell wall components to root hair shank, here, we demonstrate that root hair-specific Qa-SNARE, SYP123, localizes to the subapical zone and shank of elongating root hairs in Arabidopsis. SYP123-mediated root hair elongation was inhibited by the FAB1 inhibitor YM201636, and inhibition of PtdIns(3,5)P2 production impaired the plasma membrane localization of SYP123. We also showed that SYP123 forms a SNARE complex with VAMP727 on the plasma membrane, and syp123 and vamp727 mutants exhibited lower cell wall stiffness in the root hair shank because of impaired deposition of inner cell wall components. These results indicate that SYP123/VAMP727-mediated secretion is involved in the transport of inner cell wall components for hardening of the root hair shank.

scholarly journals NAC transcription factor RD26 is a regulator of root hair morphogenic plasticity

2021 ◽  
Author(s):  
Iman Kamranfar ◽  
Salma Balazadeh ◽  
Bernd Mueller-Roeber
Keyword(s):  
Cell Wall ◽  
Transcription Factor ◽  
Drought Stress ◽  
Root Hair ◽  
Regulatory Network ◽  
Hair Growth ◽  
Root Hairs ◽  
Nac Transcription Factor ◽  
Numerous Cell ◽  
Root Hair Growth

AbstractRoot hairs are outgrowths of epidermal cells central for water and nutrient acquisition. Root hair growth is plastically modified by environmental cues. A frequent response to water limitation is active shortening of root hairs, involving largely unknown molecular mechanisms. A root hair-specific cis-regulatory element (RHE) integrates developmental cues with downstream signalling of root hair morphogenesis. Here, we demonstrate NAC transcription factor RD26 to be a key expressional regulator of this drought stress-triggered developmental response in Arabidopsis thaliana. RD26 directly represses RSL4 and RSL1, two master transcription regulators of root hair morphogenesis, by binding RHE. RD26 further represses core cell wall modification genes including expansins (EXPA7, EXPA18), hydroxyproline-rich glycoproteins (LRX1), xyloglucan endotransglucosylases/hydrolases (XTH12, 13, 14, 26), class III peroxidases (PRX44) and plasma membrane H+-ATPase (AHA7) through RHE. Of note, several RD26-repressed genes are activated by RSL4. Thus, by repressing RSL4 and numerous cell wall-related genes, RD26 governs a robust gene regulatory network for restricting root hair growth under drought. A similar regulatory network exists in tomato, indicating evolutionary conservation across species.Significance statementIn plants, root hairs play a vital role for water and nutrient acquisition, soil anchorage, and microbial interactions. During drought stress, root hair growth is suppressed as an adaptive strategy to save cellular energy. We identified NAC transcription factor RD26 as a key regulator of this developmental plasticity in the model plant Arabidopsis thaliana. RD26 directly and negatively controls the transcriptional activity of key root hair developmental genes, RSL1 and RSL4. Furthermore, RD26 suppresses the expression of several functional genes underlying root hair development including numerous cell wall-related genes. RD26 thus governs a robust gene regulatory network underlying the developmental response to drought stress. A similar regulatory network exists in tomato indicating evolutionary conservation of this mechanism across species.

scholarly journals Apoplastic class III peroxidases PRX62 and PRX69 regulate ROS-homeostasis and cell wall associated extensins linked to root hair growth at low-temperature in Arabidopsis thaliana

2021 ◽  
Author(s):  
Javier Martínez Pacheco ◽  
Philippe Ranocha ◽  
Luciana Kasulin ◽  
Corina M. Fusari ◽  
Lucas Servi ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Wall ◽  
Low Temperature ◽  
Root Hair ◽  
Developmental Process ◽  
Association Studies ◽  
Root Hairs ◽  
Genome Wide Association Studies ◽  
Class Iii ◽  
Ros Homeostasis

Root hairs (RH) growth is highly influenced by endogenous as well as by external environmental signals that coordinately regulate its final cell size. RHs actively expand the root surface responsible for nutrient uptake and water absorption. We have recently determined that RH growth was unexpectedly boosted when Arabidopsis thaliana seedlings are cultivated at low temperatures. It was proposed that RH growth plasticity in response to cold was linked to a reduced nutrient availability in the media. Here, we explored the molecular basis of this strong RH growth response by using the Genome Wide Association Studies (GWAS) approach on Arabidopsis thaliana natural accessions. We identified the poorly characterized PEROXIDASE 62 (PRX62) as a key protein triggering this conditional growth under a moderate low-temperature stress. In addition, we identified the related protein PRX69 as an important factor in this developmental process. The prx62 prx69 double mutant and the PRX62 and PRX69 over-expressing lines showed contrasting RH phenotypes, peroxidase activities and cyt/apoReactive Oxygen Species (ROS) levels. Strikingly, a cell wall protein extensin (EXT) reporter revealed the effect of peroxidase activity on the EXT cell wall association at 10C in the RH apical zone. EXT cell wall insolubilization was enhanced at 10C, which was completely abolished under the PRX inhibitor salicylhydroxamic acid (SHAM) treatment. Finally, we demonstrated that the Root Hair defective 6 like 4 (RSL4) transcription factor directly controls the expression of PRX69 under low-temperature. Collectively, our results indicate that both PRX62 and PRX69 are key apoplastic PRXs that modulate ROS-homeostasis and cell wall EXT-insolubilization linked to RH elongation at low-temperature.

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