The Infection Process and Nodule Development

1990 ◽  
pp. 61-81 ◽  
Author(s):  
Alison M. Berry ◽  
Leslie A. Sunell
Keyword(s):  
Infection Process ◽  
Nodule Development

scholarly journals Expression of small GTPases in the roots and nodules of Medicago truncatula cv. Jemalong

2019 ◽  
Vol 78 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Abdul Razaque Memon ◽  
Christiane Katja Schwager ◽  
Karsten Niehaus
Keyword(s):  
Medicago Truncatula ◽  
Binding Proteins ◽  
Polymerase Chain Reaction Analysis ◽  
Small Gtpases ◽  
Infection Process ◽  
Nodule Development ◽  
Gtp Binding Proteins ◽  
Gtp Binding ◽  
Differential Expression Pattern

Abstract In this study we used Medicago truncatula, to identify and analyze the expression of small GTP-binding proteins (Arf1, Arl1, Sar1, Rabs, Rop/Rac) and their interacting partners in the infection process in the roots and nodules. A real-time polymerase chain reaction analysis was carried out and our results showed that Arf1 (AtArfB1c-like), MtSar1, AtRabA1e-like, AtRabC1-like, MsRab11-like and AtRop7-like genes were highly expressed in the nodules of rhizobium inoculated plants compared to the non-inoculated ones. On the contrary, AtRabA3 like, AtRab5c and MsRac1-like genes were highly expressed in non-infected nitrogen supplied roots of M. truncatula. Other Rab genes (AtRabA4a, AtRabA4c and AtRabG3a-like genes) were nearly equally expressed in both treatments. Interestingly, RbohB (a respiratory burst NADPH oxidase homologue) was more highly expressed in rhizobium infected than in non-infected roots and nodules. Our data show a differential expression pattern of small GTP-binding proteins in roots and nodules of the plants. This study demonstrates an important role of small GTP-binding proteins in symbiosome biogenesis and root nodule development in legumes.

Light and electron microscopic studies of nodule structure of alfalfa

1981 ◽  
Vol 27 (1) ◽  
pp. 36-43 ◽  
Author(s):  
J. J. Patel ◽  
A. F. Yang
Keyword(s):  
Light And Electron Microscopy ◽  
Infection Process ◽  
Infection Thread ◽  
Nodule Development ◽  
Electron Microscopic ◽  
Meristematic Region ◽  
Microscopic Studies ◽  
A Site ◽  
Ongoing Infection ◽  
Nodule Tissue

Light and electron microscopy was used to establish the structural organisation of the developing nodule of alfalfa. In these nodules three distinct regions were noted: (1) the base region, site of original infection where the nodule is attached to the root and now composed of degenerating nodule tissue, (2) the central region, or active region composed of nodule cells containing tightly packed bacteroids surrounding a central vacuole, and (3) the meristematic region, a site of new growth, behind which newly formed cells are continually invaded. The ongoing infection process accompanying continued nodule development provided the opportunity to study the release of Rhizobium cells from the infection threads.In the nodules of alfalfa it would appear that the Rhizobium cells are released from infection thread into the nodule tissue in two different ways: (i) release with infection thread membrane and (ii) release in thin-walled vesicular structures. Thus it is concluded that Rhizobium cells are surrounded by the infection thread membrane when they are released from the infection thread into nodule tissue.

A calcium-dependent bacterial surface protein is involved in the attachment of rhizobia to peanut roots

2003 ◽  
Vol 49 (6) ◽  
pp. 399-405 ◽  
Author(s):  
Marta Dardanelli ◽  
Jorge Angelini ◽  
Adriana Fabra
Keyword(s):  
Cell Surface ◽  
Calcium Binding ◽  
Fluorescent Protein ◽  
Sodium Dodecyl ◽  
Surface Protein ◽  
Infection Process ◽  
Surface Proteins ◽  
Phase Cell ◽  
Nodule Development ◽  
Bradyrhizobium Sp

As part of a project to characterize molecules involved in the crack-entry infection process leading to nodule development, a microscopic assay was used to visualize the attachment of cells of Bradyrhizobium sp. strains SEMIA 6144 and TAL 1000 (labelled by introducing a plasmid expressing constitutively the green fluorescent protein GFP-S65T) to Arachis hypogaea L. (peanut). Qualitative and quantitative results revealed that attachment was strongly dependent on the growth phase of the bacteria. Optimal attachment occurred when bacteria were at the late log or early stationary phase. Cell surface proteins from the Bradyrhizobium sp. strains inhibited the attachment when supplied prior to the attachment assay. Root incubation with a 14-kDa protein (eluted from sodium dodecyl sulphate – gel electrophoresis of the cell surface fraction) prior to the attachment assay resulted in a strong decrease of attachment. The adhesin appeared to be a calcium-binding protein, since cells treated with EDTA were found to be able to bind to adhesin-treated peanut roots. Since this protein has properties identical to those reported for rhicadhesin, we propose that this adhesin is also involved in the attachment process of rhizobia to root legumes that are infected by the crack-entry process.Key words: peanut, crack entry, rhizobia, attachment, adhesin.

scholarly journals The Medicago truncatula Vacuolar Iron Transporter-Like proteins VTL4 and VTL8 deliver iron to endosymbiotic bacteria at different stages of the infection process

2019 ◽  
Author(s):  
Jennifer H. Walton ◽  
Gyöngyi Kontra-Kováts ◽  
Robert T. Green ◽  
Ágota Domonkos ◽  
Beatrix Horváth ◽  
...  
Keyword(s):  
Medicago Truncatula ◽  
Iron Transport ◽  
Iron Status ◽  
Root Nodules ◽  
Lotus Japonicus ◽  
Infection Process ◽  
Nodule Development ◽  
Endosymbiotic Bacteria ◽  
Iron Transporter ◽  
Late Stages

SummaryThe symbiotic relationship between legumes and rhizobium bacteria in root nodules has a high demand for iron. The host plant is known to provide iron to developing bacteroids, but questions remain regarding which transporters are involved. Here, we characterize two Vacuolar Iron Transporter-Like (VTL) proteins in Medicago truncatula that are specifically expressed during nodule development. VTL4 is mostly expressed during early infection and the protein was localized to membranes and the infection thread. vtl4 mutants were delayed in nodule development. VTL8 is closely related to SEN1 in Lotus japonicus and expressed in the late stages of bacteroid differentiation. The VTL8 protein was localized to the symbiosome membrane. A mutant line lacking the tandemly-arranged VTL4 – VTL8 genes, named 13U, was unable to develop functional nodules and failed to fix nitrogen, which was restored by expression of VTL8 alone. Using a newly developed lux reporter to monitor iron status of the bacteroids, a slight decrease in luminescence was observed in vtl4 mutants and a strong decrease in the 13U mutant. Iron transport capability of VTL4 and VTL8 was shown by yeast complementation. Taken together, these data indicate that VTL-type transporters are the main route for delivering iron to symbiotic rhizobia.

scholarly journals Double Mutant Analysis of Sequential Functioning of Pea (Pisum sativum L.) Genes: Sym13, Sym33 and Sym40 During Symbiotic Nodule Development

2010 ◽  
Vol 8 (2) ◽  
pp. 3-8 ◽  
Author(s):  
Viktor E Tsyganov ◽  
Elena V Seliverstova ◽  
Vera A Voroshilova ◽  
Anna V Tsyganova ◽  
Zlata B Pavlova ◽  
...  
Keyword(s):  
Pisum Sativum ◽  
Mutant Allele ◽  
Double Mutant ◽  
Developmental Stages ◽  
Infection Process ◽  
Nodule Development ◽  
Symbiotic Gene ◽  
Mutant Analysis ◽  
Pisum Sativum L ◽  
Symbiotic Nodule

Two double mutants carrying pea symbiotic gene pairs sym13, sym40 and sym33, sym40, respectively, were constructed using single mutants blocked at different nodule developmental stages: E135f (sym13), SGEFix–‑1 (sym40) and SGEFix–‑2 (sym33). The epistasis of the mutant allele sym40 over the mutant allele sym13 and sym33 over sym40 was shown with respect to nodule histological and ultrastructural organisation. Thus, the proposed earlier sequential functioning of genes during infection process: Sym33→Sym40→Sym13 has been confirmed. 

Development of an ineffective pea root nodule: morphogenesis, fine structure, and cytokinin biosynthesis

1977 ◽  
Vol 55 (14) ◽  
pp. 1891-1907 ◽  
Author(s):  
William Newcomb ◽  
Kunihiko Syono ◽  
John G. Torrey
Keyword(s):  
Rhizobium Leguminosarum ◽  
Nitrogenase Activity ◽  
Zeatin Riboside ◽  
Infection Process ◽  
Nodule Development ◽  
Cytokinin Biosynthesis ◽  
Low Frequencies ◽  
Host Cytoplasm ◽  
Host Membrane ◽  
Infected Cells

Roots of the garden pea Pisam sativum L. cv. Little Marvel inoculated with Rhizobium leguminosarum strain 1019 produce small white nodules which are ineffective in fixing atmospheric nitrogen. Analyses of cytokinin contents of the nodules at different ages using extraction, purification, and thin-layer chromatographic separation showed that the cytokinins zeatin and zeatin riboside and isopentenyladenine and its riboside were present in greatest amounts early in nodule development and decreased thereafter. A new unidentified cytokinin was present in older nodules. The early stages of the infection process in the ineffective nodules were similar to those observed in effective nodules. However, bacteria released from the bacterial thread via an unwalled droplet were not always surrounded by a host membrane. In later stages of nodule development many infected cells contained rhizobia with no enclosing membranes so that the bacteria were free within the host cytoplasm. Such cells showed very low frequencies of mitochondria, of polyribosomes, and endoplasmic reticulum. Thus, the biosynthetic capacity of the cells appeared to be impaired and membrane synthesis defective. The failure of the nodules to develop nitrogenase activity is probably related to the failure of membrane formation around the bacteria. Abnormalities in amyloplast formation were also noted, as well as structural differences in the nodule, including a higher proportion of uninfected cells and earlier cessation of mitotic activity in the nodule meristem than occurs in effective nodules of pea. Transfer cells were observed in the pericycle in both effective and ineffective nodules.

scholarly journals The Impairment of the Nodulation Process, Induced by a Bradyrhizobium japonicum Exopolysaccharide Mutant is Determined by the Genotype of the Host Plant

1994 ◽  
Vol 49 (11-12) ◽  
pp. 727-736 ◽  
Author(s):  
Kerstin Kosch ◽  
Andreas Jacobi ◽  
Martin Parniske ◽  
Dietrich Werner ◽  
Peter Müller
Keyword(s):  
Host Plant ◽  
Bradyrhizobium Japonicum ◽  
Early Stage ◽  
Glycine Soja ◽  
Defense Responses ◽  
Infection Process ◽  
Nodule Development ◽  
Morphological Studies ◽  
Determinate Nodule

The deletion mutant Bradyrhizobium japonicum ΔP22 produces a structurally altered exopolysaccharide. The nodulation of two cultivars each of Glycine max and Glycine soja, and cultivars of Macroptilium atropurpureum and Vigna radiata, infected with this mutant was examined in order to analyze the role of the exopolysaccharide in the infection process of plants with a determinate nodule type. All host plants analyzed exhibited delayed nodulation and formed fewer nodules per plant. The extent of the impairments depended on the genotype of the host plant. Morphological studies confirmed these results. In V radiata later steps in nodule development proceeded without further disturbances, whereas with G. soja PI 407287 minor changes were detected. In contrast, the inoculation of G. soja PI 468397 and M. atropurpureum lead to the formation of nodules most of which were not infected by Bradyrhizobium japonicum ΔP22 (Inf-). However, on M. atropurpureum at least some effective nitrogen-fixing nodules developed. Such nodules did not emerge from G. soja PI 468397. Inf- nodules were arrested in an early stage of nodule development, and symptoms of plant defense responses were observed.

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.

scholarly journals Roles for Azorhizobial Nod Factors and Surface Polysaccharides in Intercellular Invasion and Nodule Penetration, Respectively

1998 ◽  
Vol 11 (10) ◽  
pp. 999-1008 ◽  
Author(s):  
Wim D'Haeze ◽  
Mengsheng Gao ◽  
Riet De Rycke ◽  
Marc Van Montagu ◽  
Gilbert Engler ◽  
...  
Keyword(s):  
Infection Process ◽  
Nodule Development ◽  
Nod Factors ◽  
Symbiotic Interaction ◽  
Simultaneous Application ◽  
Infection Threads ◽  
Cortical Infection ◽  
Surface Polysaccharides ◽  
Altered Surface ◽  
Cortical Regions

In the symbiotic interaction between Azorhizobium caulinodans and Sesbania rostrata root and stem-borne nodules are formed. The bacteria enter the host via intercellular spaces at lateral or adventitious root bases and form infection pockets in outer cortical layers. Infection threads guide the bacteria to nodule primordia where plant cells are invaded. To identify bacterial functions that are required for this infection process, two mutants defective in nodulation were studied; one produced no Nod factors (nodA mutant), the other had altered surface polysaccharides (SPS) and induced the formation of pseudo-nodules. Bacteria were visualized with the help of a nodA-uidA reporter fusion that was functional during nodule development and in bacteroids. In contrast to the SPS mutant, nodA mutants were unable to colonize outer cortical regions. In mixed inoculations with both mutants, functional nodules were formed, the central tissue of which was occupied by the nodA mutant. These observations suggest that SPS play a role in deeper invasion and that Nod factors are necessary for entry. Simultaneous application of purified Nod factors and nodA mutant bacteria restored the formation of outer cortical infection pockets leading to the conclusion that intercellular infection is an active process that is dependent on bacterial Nod factor signaling.

scholarly journals Novel rkp Gene Clusters ofSinorhizobium meliloti Involved in Capsular Polysaccharide Production and Invasion of the Symbiotic Nodule: the rkpKGene Encodes a UDP-Glucose Dehydrogenase

1998 ◽  
Vol 180 (20) ◽  
pp. 5426-5431 ◽  
Author(s):  
Attila Kereszt ◽  
Ernő Kiss ◽  
Bradley L. Reuhs ◽  
Russell W. Carlson ◽  
Ádám Kondorosi ◽  
...  
Keyword(s):  
Sinorhizobium Meliloti ◽  
Capsular Polysaccharide ◽  
Rhizobium Meliloti ◽  
Glucose Dehydrogenase ◽  
Attachment Site ◽  
Gene Clusters ◽  
Protein Product ◽  
Infection Process ◽  
Nodule Development ◽  
Symbiotic Nodule

ABSTRACT The production of exopolysaccharide (EPS) was shown to be required for the infection process by rhizobia that induce the formation of indeterminate nodules on the roots of leguminous host plants. InSinorhizobium meliloti (also known as Rhizobium meliloti) Rm41, a capsular polysaccharide (KPS) analogous to the group II K antigens of Escherichia coli can replace EPS during symbiotic nodule development and serve as an attachment site for the strain-specific bacteriophage φ16-3. The rkpA to -J genes in the chromosomal rkp-1 region code for proteins that are involved in the synthesis, modification, and transfer of an as-yet-unknown lipophilic molecule which might function as a specific lipid carrier during KPS biosynthesis. Here we report that with a phage φ16-3-resistant population obtained after random Tn5 mutagenesis, we have identified novel mutants impaired in KPS production by genetic complementation and biochemical studies. The mutations represent two novel loci, designated therkp-2 and rkp-3 regions, which are required for the synthesis of rhizobial KPS. The rkp-2 region harbors two open reading frames (ORFs) organized in monocistronic transcription units. Although both genes are required for normal lipopolysaccharide production, only the second one, designated rkpK, is involved in the synthesis of KPS. We have demonstrated that RkpK possesses UDP-glucose dehydrogenase activity, while the protein product of ORF1 might function as a UDP-glucuronic acid epimerase.

Sign in / Sign up

Export Citation Format

Share Document