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 The Medicago truncatula MtAnn1 Gene Encoding an Annexin Is Induced by Nod Factors and During the Symbiotic Interaction with Rhizobium meliloti

1998 ◽  
Vol 11 (6) ◽  
pp. 504-513 ◽  
Author(s):  
Fernanda de Carvalho Niebel ◽  
Nicole Lescure ◽  
Julie V. Cullimore ◽  
Pascal Gamas
Keyword(s):  
Medicago Truncatula ◽  
Rhizobium Meliloti ◽  
Marker Gene ◽  
Distal Region ◽  
Infection Process ◽  
Biologically Active ◽  
Nod Factors ◽  
Symbiotic Interaction ◽  
Symbiotic Associations ◽  
Infection Threads

Here we report the characterization of a new Nod factor-induced gene from Medicago truncatula identified by mRNA differential display. This gene, designated MtAnn1, encodes a protein homologous to the annexin family of calcium- and phospholipid-binding proteins. We further show that the MtAnn1 gene is also induced during symbiotic associations with Rhizobium meliloti, both at early stages in bacterial-inoculated roots and in nodule structures. By in situ hybridization, we demonstrate that MtAnn1 expression in nodules is mainly associated with the distal region of invasion zone II not containing infection threads, revealing MtAnn1 as a new marker gene of the pre-infection zone. Moreover, analyses of MtAnn1 expression in response to bacterial symbiotic mutants suggest that the expression of MtAnn1 during nodulation requires biologically active Nod factors and is independent of the infection process.

scholarly journals Evidence for the Involvement in Nodulation of the Two Small Putative Regulatory Peptide-Encoding Genes MtRALFL1 and MtDVL1

2008 ◽  
Vol 21 (8) ◽  
pp. 1118-1127 ◽  
Author(s):  
Jean-Philippe Combier ◽  
Helge Küster ◽  
Etienne-Pascal Journet ◽  
Natalija Hohnjec ◽  
Pascal Gamas ◽  
...  
Keyword(s):  
Nodule Development ◽  
Strong Increase ◽  
Nod Factors ◽  
Plant Host ◽  
Symbiotic Interaction ◽  
Nod Factor ◽  
Infection Threads ◽  
Genes Encoding ◽  
Supernodulating Mutant ◽  
Increased Sensitivity

Nod factors are key bacterial signaling molecules regulating the symbiotic interaction between bacteria known as rhizobia and leguminous plants. Studying plant host genes whose expression is affected by Nod factors has given insights into early symbiotic signaling and development. Here, we used a double supernodulating mutant line that shows increased sensitivity to Nod factors to study the Nod factor-regulated transcriptome. Using microarrays containing more than 16,000 70-mer oligonucleotide probes, we identified 643 Nod-factor-regulated genes, including 225 new Nod-factor-upregulated genes encoding many potential regulators. Among the genes found to be Nod factor upregulated, we identified and characterized MtRALFL1 and MtDVL1, which code for two small putative peptide regulators of 135 and 53 amino acids, respectively. Expression analysis confirmed that these genes are upregulated during initial phases of nodulation. Overexpression of MtRALFL1 and MtDVL1 in Medicago truncatula roots resulted in a marked reduction in the number of nodules formed and in a strong increase in the number of aborted infection threads. In addition, abnormal nodule development was observed when MtRALFL1 was overexpressed. This work provides evidence for the involvement of new putative small-peptide regulators during nodulation.

scholarly journals NO Network for Plant–Microbe Communication Underground: A Review

2021 ◽  
Vol 12 ◽  
Author(s):  
Anjali Pande ◽  
Bong-Gyu Mun ◽  
Da-Sol Lee ◽  
Murtaza Khan ◽  
Geun-Mo Lee ◽  
...  
Keyword(s):  
Mycorrhizal Fungi ◽  
Nodule Development ◽  
Symbiotic Interaction ◽  
Plant Microbe Interaction ◽  
Nodule Senescence ◽  
Infection Threads ◽  
Molecular Patterns ◽  
Defense Studies ◽  
Hair Curling

Mechanisms governing plant–microbe interaction in the rhizosphere attracted a lot of investigative attention in the last decade. The rhizosphere is not simply a source of nutrients and support for the plants; it is rather an ecosystem teeming with diverse flora and fauna including different groups of microbes that are useful as well as harmful for the plants. Plant–microbe interaction occurs via a highly complex communication network that involves sophisticated machinery for the recognition of friend and foe at both sides. On the other hand, nitric oxide (NO) is a key, signaling molecule involved in plant development and defense. Studies on legume–rhizobia symbiosis suggest the involvement of NO during recognition, root hair curling, development of infection threads, nodule development, and nodule senescence. A similar role of NO is also suggested in the case of plant interaction with the mycorrhizal fungi. Another, insight into the plant–microbe interaction in the rhizosphere comes from the recognition of pathogen-associated molecular patterns (PAMPs)/microbe-associated molecular patterns (MAMPs) by the host plant and thereby NO-mediated activation of the defense signaling cascade. Thus, NO plays a major role in mediating the communication between plants and microbes in the rhizosphere. Interestingly, reports suggesting the role of silicon in increasing the number of nodules, enhancing nitrogen fixation, and also the combined effect of silicon and NO may indicate a possibility of their interaction in mediating microbial communication underground. However, the exact role of NO in mediating plant–microbe interaction remains elusive. Therefore, understanding the role of NO in underground plant physiology is very important, especially in relation to the plant’s interaction with the rhizospheric microbiome. This will help devise new strategies for protection against phytopathogens and enhancing plant productivity by promoting symbiotic interaction. This review focuses on the role of NO in plant–microbe communication underground.

scholarly journals Rhizobial Exopolysaccharides: Genetic Regulation of Their Synthesis and Relevance in Symbiosis with Legumes

2021 ◽  
Vol 22 (12) ◽  
pp. 6233
Author(s):  
Sebastián Acosta-Jurado ◽  
Francisco Fuentes-Romero ◽  
Jose-Enrique Ruiz-Sainz ◽  
Monika Janczarek ◽  
José-María Vinardell
Keyword(s):  
Genetic Regulation ◽  
Bacterial Invasion ◽  
Rhizobial Strain ◽  
Nod Factors ◽  
Root Infection ◽  
Symbiotic Interaction ◽  
Cell Association ◽  
Acidic Polysaccharides ◽  
Surface Polysaccharides ◽  
Complex Regulation

Rhizobia are soil proteobacteria able to engage in a nitrogen-fixing symbiotic interaction with legumes that involves the rhizobial infection of roots and the bacterial invasion of new organs formed by the plant in response to the presence of appropriate bacterial partners. This interaction relies on a complex molecular dialogue between both symbionts. Bacterial N-acetyl-glucosamine oligomers called Nod factors are indispensable in most cases for early steps of the symbiotic interaction. In addition, different rhizobial surface polysaccharides, such as exopolysaccharides (EPS), may also be symbiotically relevant. EPS are acidic polysaccharides located out of the cell with little or no cell association that carry out important roles both in free-life and in symbiosis. EPS production is very complexly modulated and, frequently, co-regulated with Nod factors, but the type of co-regulation varies depending on the rhizobial strain. Many studies point out a signalling role for EPS-derived oligosaccharides in root infection and nodule invasion but, in certain symbiotic couples, EPS can be dispensable for a successful interaction. In summary, the complex regulation of the production of rhizobial EPS varies in different rhizobia, and the relevance of this polysaccharide in symbiosis with legumes depends on the specific interacting couple.

scholarly journals New Nodulation Mutants Responsible for Infection Thread Development in Lotus japonicus

2006 ◽  
Vol 19 (7) ◽  
pp. 801-810 ◽  
Author(s):  
Koji Yano ◽  
Myra L. Tansengco ◽  
Taihei Hio ◽  
Kuniko Higashi ◽  
Yoshikatsu Murooka ◽  
...  
Keyword(s):  
Developmental Process ◽  
Lotus Japonicus ◽  
Infection Thread ◽  
Nodule Development ◽  
Short Root ◽  
Symbiotic Interaction ◽  
Model Legume ◽  
Infection Threads ◽  
Nodulation Mutants ◽  
Legume Plants

Legume plants develop specialized root organs, the nodules, through a symbiotic interaction with rhizobia. The developmental process of nodulation is triggered by the bacterial microsymbiont but regulated systemically by the host legume plants. Using ethylmethane sulfonate mutagenesis as a tool to identify plant genes involved in symbiotic nodule development, we have isolated and analyzed five nodulation mutants, Ljsym74-3, Ljsym79-2, Ljsym79-3, Ljsym80, and Ljsym82, from the model legume Lotus japonicus. These mutants are defective in developing functional nodules and exhibit nitrogen starvation symptoms after inoculation with Mesorhizobium loti. Detailed observation revealed that infection thread development was aborted in these mutants and the nodules formed were devoid of infected cells. Mapping and complementation tests showed that Ljsym74-3, and Ljsym79-2 and Ljsym79-3, were allelic with reported mutants of L. japonicus, alb1 and crinkle, respectively. The Ljsym82 mutant is unique among the mutants because the infection thread was aborted early in its development. Ljsym74-3 and Ljsym80 were characterized as mutants with thick infection threads in short root hairs. Map-based cloning and molecular characterization of these genes will help us understand the genetic mechanism of infection thread development in L. japonicus.

scholarly journals Nodule Development Induced by Mesorhizobium loti Mutant Strains Affected in Polysaccharide Synthesis

2005 ◽  
Vol 18 (5) ◽  
pp. 446-457 ◽  
Author(s):  
Alejandra L. D'Antuono ◽  
Adriana Casabuono ◽  
Alicia Couto ◽  
Rodolfo A. Ugalde ◽  
Viviana C. Lepek
Keyword(s):  
Pleiotropic Effect ◽  
Nodule Development ◽  
Wild Type ◽  
Mesorhizobium Loti ◽  
O Antigen ◽  
Polysaccharide Synthesis ◽  
Infection Threads ◽  
Surface Polysaccharides ◽  
Hair Curling

The role of Mesorhizobium loti surface polysaccharides on the nodulation process is not yet fully understood. In this article, we describe the nodulation phenotype of mutants affected in the synthesis of lipopolysaccharide (LPS) and β(1,2) cyclic glucan. M. loti lps β2 mutant produces LPS with reduced amount of O-antigen, whereas M. loti lps β1 mutant produces LPS totally devoid of O-antigen. Both genes are clustered in the chromosome. Based on amino acid sequence homology, LPS sugar composition, and enzymatic activity, we concluded that lps β2 codes for an enzyme involved in the transformation of dTDP-glucose into dTDP-rhamnose, the sugar donor of rhamnose for the synthesis of O-antigen. On the other hand, lps β1 codes for a glucosyl transferase involved in the biosynthesis of the O-antigen. Although LPS mutants elicited normal nodules, both show reduced competitiveness compared with the wild type. M. loti β(1-2) cyclic glucan synthase (cgs) mutant induces white, empty, ineffective pseudonodules in Lotus tenuis. Cgs mutant induces normal root hair curling but is unable to induce the formation of infection threads. M. loti cgs mutant was more sensitive to deoxycholate and displayed motility impairment compared with the wild-type strain. This pleiotropic effect depends on calcium concentration and temperature.

scholarly journals Rhizobial Exopolysaccharides: Genetic Regulation of Their Synthesis and Relevance in Symbiosis With Legumes

2021 ◽  
Author(s):  
Sebastián Acosta-Jurado ◽  
Francisco Fuentes-Romero ◽  
Jose-Enrique Ruiz-Sainz ◽  
Monika Janczarek ◽  
José-María Vinardell
Keyword(s):  
Genetic Regulation ◽  
Bacterial Invasion ◽  
Rhizobial Strain ◽  
Nod Factors ◽  
Root Infection ◽  
Symbiotic Interaction ◽  
Cell Association ◽  
Surface Polysaccharides ◽  
Complex Regulation

Abstract: Rhizobia are soil proteobacteria able to engage in a nitrogen-fixing symbiotic interaction with legumes which involves root rhizobial infection and bacterial invasion of new organs formed by the plant in response to the presence of appropriate bacterial partners. This interaction relies on a complex molecular dialogue between both symbionts. Bacterial N-acetyl-glucosamine oligomers called Nod factors are indispensable in most cases for early steps of the symbiotic interaction. In addition, different rhizobial surface polysaccharides, such as exopolysaccharides (EPS), may also be symbiotically relevant. EPS are acidic polysaccharides located out of the cell with little or no cell association that carry out important roles both in free-life and in symbiosis. EPS production is very complexly modulated and, frequently, co-regulated with that of Nod factors, but the type of co-regulation varies depending on the rhizobial strain. Many studies point out a signalling role of EPS-derived oligosaccharides in root infection and nodule invasion but, in certain symbiotic couples, EPS can be dispensable for a successful interaction. In summary, the complex regulation of the production of rhizobial EPS varies in different rhizobia and the relevance of this polysaccharide in symbiosis with legumes depends on the specific interacting couple.

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 Identification of Symbiotically Defective Mutants of Lotus japonicus Affected in Infection Thread Growth

2006 ◽  
Vol 19 (12) ◽  
pp. 1444-1450 ◽  
Author(s):  
Fabien Lombardo ◽  
Anne B. Heckmann ◽  
Hiroki Miwa ◽  
Jillian A. Perry ◽  
Koji Yano ◽  
...  
Keyword(s):  
Root Hair ◽  
Plant Cell Wall ◽  
Plant Root ◽  
Lotus Japonicus ◽  
Cortical Cell ◽  
Host Cells ◽  
Infection Thread ◽  
Mycorrhizal Symbiosis ◽  
Symbiotic Interaction ◽  
Infection Threads

During the symbiotic interaction between legumes and rhizobia, the host cell plasma membrane and associated plant cell wall invaginate to form a tunnel-like infection thread, a structure in which bacteria divide to reach the plant root cortex. We isolated four Lotus japonicus mutants that make infection pockets in root hairs but form very few infection threads after inoculation with Mesorhizobium loti. The few infection threads that did initiate in the mutants usually did not progress further than the root hair cell. These infection-thread deficient (itd) mutants were unaffected for early symbiotic responses such as calcium spiking, root hair deformation, and curling, as well as for the induction of cortical cell division and the arbuscular mycorrhizal symbiosis. Complementation tests and genetic mapping indicate that itd2 is allelic to Ljsym7, whereas the itd1, itd3, and itd4 mutations identified novel loci. Bacterial release into host cells did occur occasionally in the itd1, itd2, and itd3 mutants suggesting that some infections may succeed after a long period and that infection of nodule cells could occur normally if the few abnormal infection threads that were formed reached the appropriate nodule cells.

scholarly journals H2O2 Is Required for Optimal Establishment of the Medicago sativa/Sinorhizobium meliloti Symbiosis

2007 ◽  
Vol 189 (23) ◽  
pp. 8741-8745 ◽  
Author(s):  
Alexandre Jamet ◽  
Karine Mandon ◽  
Alain Puppo ◽  
Didier Hérouart
Keyword(s):  
Medicago Sativa ◽  
Plant Cell ◽  
Sinorhizobium Meliloti ◽  
Root Hairs ◽  
Symbiotic Interaction ◽  
Infection Threads ◽  
Cell Layers

ABSTRACT The symbiotic interaction between Medicago sativa and Sinorhizobium meliloti RmkatB ++ overexpressing the housekeeping catalase katB is delayed, and this delay is combined with an enlargement of infection threads. This result provides evidence that H2O2 is required for optimal progression of infection threads through the root hairs and plant cell layers.

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