Fine structure of root hair infection leading to nodulation in the Frankia–Alnus symbiosis

Root hair infection by Frankia (Actinomycetales) is the means by which nitrogen-fixing root nodules are initiated upon the actinorhizal host, Alnus rubra. Structural details of the infectious process and the changes in host root hair cells are demonstrated at the prenodule stage for the first time using light and transmission electron microscopy. The Frankia hypha is the infective agent, extending from the rhizosphere through the root hair wall in a highly deformed region of the hair. There is no evidence of pleomorphism of the Frankia hypha. The primary wall fibrils of the root hair appear disorganized at the site of penetration. There is extensive secondary wall formation in the infected hair. At the site of penetration, root hair cell wall ingrowths occur that are structurally consistent with transfer cell wall formation. The ingrowths are continuous with the encapsulating wall layer surrounding the Frankia hypha The host cytoplasm is rich in ribosomes, secretory products, and organelles, including Golgi bodies, mitochondria, plastids, and profiles of endoplasmic reticulum. In an aborted infection sequence, some structural features of the host response to Frankia are observable, while other aspects of successful infection do not occur. Limited transfer cell wall is formed at the site of near infection. The root hair cytoplasm is senescent, however, and a callosic plug appears to surround the pathway of infection.

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The Arabidopsis Root Hair Cell Wall Formation Mutant lrx1 Is Suppressed by Mutations in the RHM1 Gene Encoding a UDP-l-Rhamnose Synthase

The Plant Cell ◽

10.1105/tpc.105.038653 ◽

2006 ◽

Vol 18 (7) ◽

pp. 1630-1641 ◽

Cited By ~ 77

Author(s):

Anouck Diet ◽

Bruce Link ◽

Georg J. Seifert ◽

Barbara Schellenberg ◽

Ulrich Wagner ◽

...

Keyword(s):

Cell Wall ◽

Hair Cell ◽

Root Hair ◽

Cell Wall Formation ◽

Gene Encoding ◽

Arabidopsis Root ◽

Wall Formation ◽

Root Hair Cell

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Colonization and invasion of peanut (Arachis hypogaea L.) roots by gusA-marked Bradyrhizobium sp.

Canadian Journal of Botany ◽

10.1139/b01-050 ◽

2001 ◽

Vol 79 (6) ◽

pp. 733-738 ◽

Cited By ~ 2

Author(s):

Eiji Uheda ◽

Hiroyuki Daimon ◽

Fumiki Yoshizako

Keyword(s):

Cell Wall ◽

Arachis Hypogaea ◽

Hair Cells ◽

Root Hair ◽

Root Nodules ◽

Lateral Roots ◽

Middle Lamella ◽

Root Surface ◽

Arachis Hypogaea L ◽

Root Hair Cells

Tufted rosettes of long root hairs occur in axils of young lateral roots of peanut (Arachis hypogaea L.). Analyses of serial sections of the axils of emerging lateral roots revealed multiple layers of root hair cells. The cells of the outer layer partially overlie the adjacent cells of the inner layer. When Bradyrhizobium cells with an integrated gusA gene were inoculated onto peanut roots and the roots subsequently stained with X-gluc, blue spots indicating the presence of colonies of Bradyrhizobium were observed in the axils of lateral roots. Blue spots were also observed in other areas on the root surface. Transmission electron microscopy revealed that the primary wall of the base of root hair cells has a loose construction. Upon inoculation of Bradyrhizobium, bacteria entered only between root hair cells through the middle lamella. In other areas of the root surface other than axils of lateral roots, the cells had modified walls similar to those at the base of root hair cells. However, invasion by Bradyrhizobium of the cell wall was not observed.Key words: Arachis hypogaea, gusA-marked Bradyrhizobium, cell wall, invasion, root hair cell, root nodules.

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Synergistic interaction of the two paralogous Arabidopsis genes LRX1 and LRX2 in cell wall formation during root hair development

The Plant Journal ◽

10.1046/j.1365-313x.2003.01784.x ◽

2003 ◽

Vol 35 (1) ◽

pp. 71-81 ◽

Cited By ~ 71

Author(s):

N. Baumberger ◽

M. Steiner ◽

U. Ryser ◽

B. Keller ◽

C. Ringli

Keyword(s):

Cell Wall ◽

Root Hair ◽

Synergistic Interaction ◽

Cell Wall Formation ◽

Wall Formation ◽

Root Hair Development ◽

Hair Development

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Ontogeny and fine structure of effective root nodules of the autumn olive (Elaeagnus umbellata)

Canadian Journal of Botany ◽

10.1139/b87-012 ◽

1987 ◽

Vol 65 (1) ◽

pp. 80-94 ◽

Cited By ~ 6

Author(s):

William Newcomb ◽

Dwight Baker ◽

John G. Torrey

Keyword(s):

Cell Wall ◽

Cell Walls ◽

Root Nodules ◽

Freeze Fracture ◽

Wall Layer ◽

Void Space ◽

Elaeagnus Umbellata ◽

Autumn Olive ◽

Clear Area ◽

Glycogen Particles

An ultrastructural study of effective root nodules of the autumn olive (Elaeagnus umbellata Thunb.) demonstrated the presence of hyphal and vesicular forms of the actinomycete endophyte. No sporangial forms of the endophyte were observed within these nodules. The hyphae contained septa, prominent nucleoid regions, and many ribosomes. The endophytic vesicles were initially nonseptate and then became multichambered as a result of the inward growth of complete and incomplete septa. Glycogen particles were numerous in nonseptate and early stages of septate endophytic vesicle formation and in adjacent hyphae but were absent in more developed stages of septate endophytic vesicles. The endophytic vesicles also contained prominent nucleoid areas, vesicular mesosomes, and crystalline-like striated bodies. A capsule, probably derived from host Golgi cisternae and profiles of dilated rough endoplasmic reticulum, surrounded both forms of the endophyte. The endophytic vesicle cell walls consisted of an outer layer continuous with the hyphal cell wall, a middle clear area or “void space,” and an electron-dense inner layer. The “void space” of the endophyte cell wall was resolved into many thin laminae by freeze–fracture microscopy. The laminae were presumed to be different from the outermost cell wall layer because they were washed out in the solvents used in preparing specimens for the TEM.

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Cell wall texture in root hairs of the genus Equisetum

Canadian Journal of Botany ◽

10.1139/b86-293 ◽

1986 ◽

Vol 64 (10) ◽

pp. 2201-2206 ◽

Cited By ~ 14

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.

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The structural basis for infection of root hairs of Trifolium repens by Rhizobium

Canadian Journal of Botany ◽

10.1139/b81-223 ◽

1981 ◽

Vol 59 (9) ◽

pp. 1647-1664 ◽

Cited By ~ 124

Author(s):

Dale A. Callaham ◽

John G. Torrey

Keyword(s):

Trifolium Repens ◽

Root Hair ◽

Hydrolytic Enzymes ◽

Root Hairs ◽

Structural Basis ◽

Physical Constraints ◽

Root Hair Cell ◽

Host Cytoplasm ◽

Infected Root ◽

Root Hair Infection

Root hair infection of Trifolium repens L. by Rhizobium trifolii was investigated with regard to the structural basis of infection thread origin. Most infected root hairs were shown to have in common an enclosed region at-the site of thread origin formed by specialized root hair growth or contacts. Electron micrographs of diverse infection sites showed in every case a degradation of the root hair wall at the site of thread origin within the enclosure. The thread wall is a new layer formed by apposition of material by the host cytoplasm near the penetrated wall and surrounding the break as encapsulation of the invading rhizobia. It is suggested that rhizobial enzymes provide for degradative penetration of the root hair cell wall and that localized concentrated activity of hydrolytic enzymes as well as protection from cell lysis is favored by physical constraints provided by the deformed root hair enclosures.

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

10.1101/2020.12.28.424500 ◽

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.

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Rhizobium sp. Degradation of Legume Root Hair Cell Wall at the Site of Infection Thread Origin

Applied and Environmental Microbiology ◽

10.1128/aem.50.3.717-720.1985 ◽

1985 ◽

Vol 50 (3) ◽

pp. 717-720 ◽

Cited By ~ 27

Author(s):

Robert W. Ridge ◽

Barry G. Rolfe

Keyword(s):

Cell Wall ◽

Hair Cell ◽

Root Hair ◽

Infection Thread ◽

Root Hair Cell ◽

Rhizobium Sp

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

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100161047 ◽

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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