Infection of Root Hairs by Rhizobia: Infection Thread Development with Emphasis on the Microtubular Cytoskeleton

Root Hairs ◽  
2000 ◽  
pp. 223-239 ◽  
Author(s):  
Antonius C. J. Timmers
Keyword(s):  
Root Hairs ◽  
Infection Thread ◽  
Microtubular Cytoskeleton

Infection thread formation as a basis of nodulation specificity in Rhizobium – strawberry clover associations

1969 ◽  
Vol 15 (10) ◽  
pp. 1133-1136 ◽  
Author(s):  
Diana Li ◽  
D. H. Hubbell
Keyword(s):  
Characteristic Root ◽  
Root Hairs ◽  
Infection Thread ◽  
Root Hair Deformation ◽  
Infection Threads ◽  
Specific Substance ◽  
Thread Formation ◽  
Nodulation Specificity ◽  
Infection Thread Formation

The basis for determination of nodulating specificity in Rhizobium–clover associations was investigated. Thirteen strains of rhizobia from eight different cross-inoculation groups were used to inoculate aseptically grown strawberry clover seedlings in slide culture. Microscopic observation revealed that each strain produced characteristic root hair deformation but infection threads and nodules were observed only in the homologous combination. It is concluded that, in rhizobia–clover combinations which nodulate via infection threads, specificity is determined at or before infection thread initiation. Observations of other workers that rhizobia produce a strain-specific substance affecting growth and morphology of legume root hairs were confirmed by results of this study.

scholarly journals Mechanism of Infection Thread Elongation in Root Hairs of Medicago truncatula and Dynamic Interplay with Associated Rhizobial Colonization

2008 ◽  
Vol 148 (4) ◽  
pp. 1985-1995 ◽  
Author(s):  
Joëlle Fournier ◽  
Antonius C.J. Timmers ◽  
Björn J. Sieberer ◽  
Alain Jauneau ◽  
Mireille Chabaud ◽  
...  
Keyword(s):  
Medicago Truncatula ◽  
Root Hairs ◽  
Infection Thread ◽  
Dynamic Interplay

Early events in the infection of soybean by Rhizobium japonicum. Time course and cytology of the initial infection process

1982 ◽  
Vol 60 (2) ◽  
pp. 152-161 ◽  
Author(s):  
B. Gillian Turgeon ◽  
Wolfgang D. Bauer
Keyword(s):  
Root Hair ◽  
Time Course ◽  
Cortical Cell ◽  
Root Hairs ◽  
Infection Process ◽  
Infection Thread ◽  
Rhizobium Japonicum ◽  
Outer Cortex ◽  
Light Microscope Level ◽  
Infection Threads

The time course of early infection events in Glycine max following inoculation with Rhizobium japonicum is described. Bacteria became attached to epidermal cells and root hairs within minutes of inoculation. Marked root hair curling occurred within 12 h. Infection thread formation was visible at the light microscope level of resolution about 24 h after inoculation. Infections were observed in short, tightly curled root hairs. These root hairs had not yet emerged at the time of inoculation. Infection threads appeared to originate in pockets formed by contact of the cell wall of the curled root hair with itself. Infection threads in the hairs were multiple and (or) branched. By 48 h, the infection thread(s) had progressed to the base of the root hair but had not yet penetrated into the cortex. Increases in cortical cell cytoplasm and in mitotic division occurred in advance of the penetrating infection thread. A nodule meristem developed in the outer cortex next to the infected root hair by 4 days and was accompanied by cell division across the cortex.

scholarly journals Transformed Hairy Roots of Arachis hypogea: A Tool for Studying Root Nodule Symbiosis in a Non–Infection Thread Legume of the Aeschynomeneae Tribe

2009 ◽  
Vol 22 (2) ◽  
pp. 132-142 ◽  
Author(s):  
Senjuti Sinharoy ◽  
Sudip Saha ◽  
Susanta Roy Chaudhury ◽  
Maitrayee DasGupta
Keyword(s):  
Hairy Roots ◽  
Fluorescent Protein ◽  
Root Hairs ◽  
Infection Thread ◽  
Natural Soil ◽  
35S Promoter ◽  
Wild Type ◽  
Cortical Cells ◽  
Arachis Hypogea ◽  
Green Fluorescent

Arachis hypogea is a non–“infection thread” (IT) legume where rhizobial entry or dissemination in the nodules never involves IT. Rhizobia invade through epidermal “cracks” and directly access the cortical cells to develop the characteristic aeschynomenoid nodules. For investigating these nonclassical nodulation features in Arachis spp., we developed an efficient procedure for Agrobacterium rhizogenes R1000-mediated transformation of this plant. In this study, we optimized the induction of hairy roots and nodulation of composite Arachis hypogea plants in the presence of Bradyrhizobium sp. (Arachis) strain NC92. 35S promoter-driven green fluorescent protein and β-glucuronidase expression indicated transformation frequency to be above 80%. The transformed roots had the characteristic rosette-type root hairs and had normal level of expression of symbiosis-related genes SymRK and CCaMK. The transgenic nodules resembled the wild-type nodules with an exception of 2 to 3%, where they structurally deviated from the wild-type nodules to form nodular roots. A 16S rRNA profile of an infected-zone metagenome indicated that identical populations of bradyrhizobia invaded both composite wild-type plants grown in natural soil. Our results demonstrate that Arachis hairy root is an attractive system for undertaking investigations of the nonclassical features associated with its nitrogen-fixing symbiotic interactions.

scholarly journals Nod Factor Perception During Infection Thread Growth Fine-Tunes Nodulation

2007 ◽  
Vol 20 (2) ◽  
pp. 129-137 ◽  
Author(s):  
Jeroen Den Herder ◽  
Celine Vanhee ◽  
Riet De Rycke ◽  
Viviana Corich ◽  
Marcelle Holsters ◽  
...  
Keyword(s):  
Light And Electron Microscopy ◽  
Cortical Cell ◽  
Root Hairs ◽  
Infection Thread ◽  
Bacterial Invasion ◽  
Nodule Formation ◽  
Nodulation Factors ◽  
Polysaccharide Synthesis ◽  
Infection Threads ◽  
Surface Polysaccharide

Bacterial nodulation factors (NFs) are essential signaling molecules for the initiation of a nitrogen-fixing symbiosis in legumes. NFs are perceived by the plant and trigger both local and distant responses, such as curling of root hairs and cortical cell divisions. In addition to their requirement at the start, NFs are produced by bacteria that reside within infection threads. To analyze the role of NFs at later infection stages, several phases of nodulation were studied by detailed light and electron microscopy after coinoculation of adventitious root primordia of Sesbania rostrata with a mixture of Azorhizobium caulinodans mutants ORS571-V44 and ORS571-X15. These mutants are deficient in NF production or surface polysaccharide synthesis, respectively, but they can complement each other, resulting in functional nodules occupied by ORS571-V44. The lack of NFs within the infection threads was confirmed by the absence of expression of an early NF-induced marker, leghemoglobin 6 of S. rostrata. NF production within the infection threads is shown to be necessary for proper infection thread growth and for synchronization of nodule formation with bacterial invasion. However, local production of NFs by bacteria that are taken up by the plant cells at the stage of bacteroid formation is not required for correct symbiosome development.

scholarly journals Role of Cellulose Fibrils and Exopolysaccharides of Rhizobium leguminosarum in Attachment to and Infection of Vicia sativa Root Hairs

2005 ◽  
Vol 18 (6) ◽  
pp. 533-538 ◽  
Author(s):  
M. C. Laus ◽  
A. A. N. van Brussel ◽  
J. W. Kijne
Keyword(s):  
Root Hair ◽  
Rhizobium Leguminosarum ◽  
Developmental Stages ◽  
Cortical Cell ◽  
Root Hairs ◽  
Infection Thread ◽  
Vicia Sativa ◽  
Wild Type ◽  
Infection Threads ◽  
Cellulose Fibrils

Infection and subsequent nodulation of legume host plants by the root nodule symbiote Rhizobium leguminosarum usually require attachment of the bacteria to root-hair tips. Bacterial cellulose fibrils have been shown to be involved in this attachment process but appeared not to be essential for successful nodulation. Detailed analysis of Vicia sativa root-hair infection by wild-type Rhizobium leguminosarum RBL5523 and its cellulose fibril-deficient celE mutant showed that wild-type bacteria infected elongated growing root hairs, whereas cellulose-deficient bacteria infected young emerging root hairs. Exopolysaccharide-deficient strains that retained the ability to produce cellulose fibrils could also infect elongated root hairs but infection thread colonization was defective. Cellulose-mediated agglutination of these bacteria in the root-hair curl appeared to prevent entry into the induced infection thread. Infection experiments with V. sativa roots and an extracellular polysaccharide (EPS)- and cellulose-deficient double mutant showed that cellulose-mediated agglutination of the EPS-deficient bacteria in the infection thread was now abolished and that infection thread colonization was partially restored. Interestingly, in this case, infection threads were initiated in root hairs that originated from the cortical cell layers of the root and not in epidermal root hairs. Apparently, surface polysaccharides of R. leguminosarum, such as cellulose fibrils, are determining factors for infection of different developmental stages of root hairs.

scholarly journals Infection and Invasion of Roots by Symbiotic, Nitrogen-Fixing Rhizobia during Nodulation of Temperate Legumes

2004 ◽  
Vol 68 (2) ◽  
pp. 280-300 ◽  
Author(s):  
Daniel J. Gage
Keyword(s):  
Root Hair ◽  
Composite Structures ◽  
Hair Growth ◽  
Root Hairs ◽  
Infection Thread ◽  
Nitrogen Fixing ◽  
Indeterminate Nodules ◽  
Infection Threads ◽  
Root Hair Growth ◽  
Temperate Legumes

SUMMARY Bacteria belonging to the genera Rhizobium, Mesorhizobium, Sinorhizobium, Bradyrhizobium, and Azorhizobium (collectively referred to as rhizobia) grow in the soil as free-living organisms but can also live as nitrogen-fixing symbionts inside root nodule cells of legume plants. The interactions between several rhizobial species and their host plants have become models for this type of nitrogen-fixing symbiosis. Temperate legumes such as alfalfa, pea, and vetch form indeterminate nodules that arise from root inner and middle cortical cells and grow out from the root via a persistent meristem. During the formation of functional indeterminate nodules, symbiotic bacteria must gain access to the interior of the host root. To get from the outside to the inside, rhizobia grow and divide in tubules called infection threads, which are composite structures derived from the two symbiotic partners. This review focuses on symbiotic infection and invasion during the formation of indeterminate nodules. It summarizes root hair growth, how root hair growth is influenced by rhizobial signaling molecules, infection of root hairs, infection thread extension down root hairs, infection thread growth into root tissue, and the plant and bacterial contributions necessary for infection thread formation and growth. The review also summarizes recent advances concerning the growth dynamics of rhizobial populations in infection threads.

scholarly journals Rhizobium lipopolysaccharide modulates infection thread development in white clover root hairs.

1991 ◽  
Vol 173 (17) ◽  
pp. 5371-5384 ◽  
Author(s):  
F B Dazzo ◽  
G L Truchet ◽  
R I Hollingsworth ◽  
E M Hrabak ◽  
H S Pankratz ◽  
...  
Keyword(s):  
White Clover ◽  
Root Hairs ◽  
Infection Thread ◽  
Clover Root

scholarly journals Entry of Rhizobium leguminosarum bv. viciae into Root Hairs Requires Minimal Nod Factor Specificity, but Subsequent Infection Thread Growth Requires nodO or nodE

2000 ◽  
Vol 13 (7) ◽  
pp. 754-762 ◽  
Author(s):  
Simon A. Walker ◽  
J. Allan Downie
Keyword(s):  
Rhizobium Leguminosarum ◽  
Root Hairs ◽  
Infection Thread ◽  
Growing Up ◽  
Subsequent Infection ◽  
Nod Factor ◽  
Infection Threads ◽  
Significant Difference ◽  
Thread Formation ◽  
Factor Specificity

Using various mutant strains of Rhizobium leguminosarum bv. viciae, we have investigated the role of nodO in stimulating infection thread development in vetch and pea. Analysis of R. leguminosarum bv. viciae nodE and nodO mutants revealed no significant difference from the wild-type infection phenotype. Conversely, an R. leguminosarum bv. viciae nodE nodO double mutant was severely impaired in its ability to form normal infection threads. This strain displayed a number of novel infection-related events, including intracellular accumulations of bacteria at the base of root hairs, distended and enlarged infection threads, and reversed threads growing up root hairs. Since normal infection was seen in a nodE mutant, nodO must suppress these abnormal infection phenomena. A deletion mutant, retaining only the nodD and nodABCIJ genes, also formed intracellular accumulations at the base of root hairs. Addition of R. leguminosarum bv. viciae nodO could alleviate this phenotype and restore some infection thread formation, although these threads appeared to be abnormal. Exogenous application of R. leguminosarum bv. viciae Nod factors could not alleviate the aberrant infection phenotype. Our results show that the most basic Nod factor structure can allow bacterial entry into the root hair, and that nodO can promote subsequent infection thread development.

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