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 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 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 Glutathione and Homoglutathione Play a Critical Role in the Nodulation Process of Medicago truncatula

2005 ◽  
Vol 18 (3) ◽  
pp. 254-259 ◽  
Author(s):  
Pierre Frendo ◽  
Judith Harrison ◽  
Christel Norman ◽  
María Jesús Hernández Jiménez ◽  
Ghislaine Van de Sype ◽  
...  
Keyword(s):  
Medicago Truncatula ◽  
Root Nodules ◽  
Critical Role ◽  
Specific Inhibitor ◽  
Buthionine Sulfoximine ◽  
Infection Process ◽  
Symbiotic Interaction ◽  
Transgenic Roots ◽  
Model Legume ◽  
Early Nodulin

Legumes form a symbiotic interaction with bacteria of the Rhizobiaceae family toproduce nitrogen-fixing root nodules under nitrogen-limiting conditions. This process involves the recognition of the bacterial Nod factors by the plant which mediates the entry of the bacteria into the root and nodule organogenesis. We have examined the importance of the low molecular weight thiols, glutathione (GSH) and homoglutathione (hGSH), during the nodulation process in the model legume Medicago truncatula. Using both buthionine sulfoximine, a specific inhibitor of GSH and hGSH synthesis, and transgenic roots expressing GSH synthetase and hGSH synthetase in an antisense orientation, we showed that deficiency in GSH and hGSH synthesis inhibited the formation of the root nodules. This inhibition was not correlated to a modification in the number of infection events or to a change in the expression of the Rhizobium sp.-induced peroxidase rip1, indicating that the low level of GSH or hGSH did not alter the first steps of the infection process. In contrast, a strong diminution in the number of nascent nodules and in the expression of the early nodulin genes, Mtenod12 and Mtenod40, were observed in GSHand hGSH-depleted plants. In conclusion, GSH and hGSH appear to be essential for proper development of the root nodules during the symbiotic interaction.

scholarly journals Symbiosis-Specific Expression of Two Medicago truncatula Nodulin Genes, MtN1 and MtN13, Encoding Products Homologous to Plant Defense Proteins

1998 ◽  
Vol 11 (5) ◽  
pp. 393-403 ◽  
Author(s):  
Pascal Gamas ◽  
Françoise de Billy ◽  
Georges Truchet
Keyword(s):  
Plant Defense ◽  
Medicago Truncatula ◽  
Pathogenic Bacteria ◽  
Rhizobium Meliloti ◽  
Infection Process ◽  
Specific Marker ◽  
Outer Cortex ◽  
Specific Expression ◽  
Defense Proteins ◽  
Nodulin Genes

Two Medicago truncatula nodulin genes putatively encoding proteins structurally related to two classes of proteins commonly associated with plant defense reactions have been characterized. MtN1 is homologous to two small, cysteine-rich, pathogen-inducible proteins from pea (pI39 and pI230), whereas MtN13 is closely related to the PR10 family of pathogenesis-related proteins. We show that neither MtN1 nor MtN13 is induced in leaves in response to pathogenic bacteria, and that both are exclusively expressed during nodulation. In situ hybridization experiments as well as Northern (RNA) studies of interactions between M. truncatula and either wild-type Rhizobium meliloti or mutants deficient in infection establish that MtN1 is associated with the infection process, while MtN13 represents the first specific marker described for the nodule outer cortex. Possible roles for MtN1 and MtN13 are discussed. We also present the identification of another member of the PR10 family, designated as MtPR10-1, whose regulation is strikingly different from that observed for MtN13, being constitutively expressed in roots and pathogen-inducible in leaves.

scholarly journals Composite Actinorhizal Plants with Transgenic Roots for the Study of Symbiotic Associations with Frankia

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Faïza Meriem Benabdoun ◽  
Mathish Nambiar-Veetil ◽  
Leandro Imanishi ◽  
Sergio Svistoonoff ◽  
Nadia Ykhlef ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Infection Process ◽  
Actinorhizal Plants ◽  
Nodule Formation ◽  
Symbiotic Genes ◽  
Actinorhizal Symbiosis ◽  
Symbiotic Interaction ◽  
Transgenic Roots ◽  
Symbiotic Associations ◽  
Composite Plants

More than 200 species of dicotyledonous plants belonging to eight different families and 24 genera can establish actinorhizal symbiosis with the nitrogen-fixing soil actinomycete Frankia. Compared to the symbiotic interaction between legumes and rhizobia, little is known about the molecular basis of the infection process and nodule formation in actinorhizal plants. Here, we review a gene transfer system based on Agrobacterium rhizogenes that opens the possibility to rapidly analyze the function of candidate symbiotic genes. The transformation protocol generates “composite plants” that consist of a nontransgenic aerial part with transformed hairy roots. Composite plants have already been obtained in three different species of actinorhizal plants, including the tropical tree species Casuarina glauca, the Patagonian shrub Discaria trinervis, and the nonwoody plant Datisca glomerata. The potential of this technique to advancing our understanding of the molecular mechanisms underlying infection by Frankia is demonstrated by functional analyses of symbiotic genes.

scholarly journals The Early Nodulin Gene MtN6 Is a Novel Marker for Events Preceding Infection of Medicago truncatula Roots by Sinorhizobium meliloti

1999 ◽  
Vol 12 (6) ◽  
pp. 544-555 ◽  
Author(s):  
R. Mathis ◽  
C. Grosjean ◽  
F. de Billy ◽  
T. Huguet ◽  
P. Gamas
Keyword(s):  
Medicago Truncatula ◽  
Sinorhizobium Meliloti ◽  
Root Nodules ◽  
Cdna Clones ◽  
Specific Marker ◽  
Nod Factors ◽  
Cortical Cells ◽  
Infection Threads ◽  
Early Nodulin ◽  
Cell Layers

MtN6 belongs to a series of cDNA clones representing Medicago truncatula genes transcriptionally activated during nodulation by Sinorhizobium meliloti (P. Gamas, F. de Carvalho Niebel, N. Lescure, and J. V. Cullimore, Mol. Plant-Microbe Interact. 9:233–242, 1996). We show here by in situ hybridization that MtN6 transcripts specifically accumulate first at very localized regions in the outer root cell layers, corresponding to outer cortical cells containing preinfection threads. At later stages, MtN6 expression is observed ahead of growing infection threads, including in the infection zone of mature root nodules. Interestingly, regulation of MtN6 is clearly distinct from that of other early nodulins expressed in the same region of the nodule, in terms of response to bacterial symbiotic mutants and to purified Nod factors. We thus suggest that MtN6 represents the first specific marker of a pathway involved in preparation to infection, which is at least partly controlled by Nod factors. Finally, we discuss the intriguing sequence homology shown by MtN6 to a protein from Emericella (Aspergillus) nidulans, FluG, that plays a key role in controlling the organogenesis of conidiophores (B. N. Lee and T. H. Adams, Genes Dev. 8:641–651, 1994).

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 Expression of Medicago truncatula Genes Responsive to Nitric Oxide in Pathogenic and Symbiotic Conditions

2008 ◽  
Vol 21 (6) ◽  
pp. 781-790 ◽  
Author(s):  
Alberto Ferrarini ◽  
Matteo De Stefano ◽  
Emmanuel Baudouin ◽  
Chiara Pucciariello ◽  
Annalisa Polverari ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Medicago Truncatula ◽  
Regulatory Networks ◽  
Sinorhizobium Meliloti ◽  
Biotic Interactions ◽  
Hypersensitive Reaction ◽  
Nodule Formation ◽  
Polymorphism Analysis ◽  
Symbiotic Interaction ◽  
Physiological Relevance

Nitric oxide (NO) is involved in diverse physiological processes in plants, including growth, development, response to pathogens, and interactions with beneficial microorganisms. In this work, a dedicated microarray representing the widest database available of NO-related transcripts in plants has been produced with 999 genes identified by a cDNA amplified fragment length polymorphism analysis as modulated in Medicago truncatula roots treated with two NO donors. The microarray then was used to monitor the expression of NO-responsive genes in M. truncatula during the incompatible interaction with the foliar pathogen Colletotrichum trifolii race 1 and during the symbiotic interaction with Sinorhizobium meliloti 1021. A wide modulation of NO-related genes has been detected during the hypersensitive reaction or during nodule formation and is discussed with special emphasis on the physiological relevance of these genes in the context of the two biotic interactions. This work clearly shows that NO-responsive genes behave differently depending on the plant organ and on the type of interaction, strengthening the need to consider regulatory networks, including different signaling molecules.

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.

scholarly journals The Medicago truncatula N5 Gene Encoding a Root-Specific Lipid Transfer Protein Is Required for the Symbiotic Interaction with Sinorhizobium meliloti

2009 ◽  
Vol 22 (12) ◽  
pp. 1577-1587 ◽  
Author(s):  
Youry Pii ◽  
Alessandra Astegno ◽  
Elisa Peroni ◽  
Massimo Zaccardelli ◽  
Tiziana Pandolfini ◽  
...  
Keyword(s):  
Medicago Truncatula ◽  
Sinorhizobium Meliloti ◽  
Lipid Transfer Protein ◽  
Symbiotic Association ◽  
Lipid Transfer ◽  
Symbiotic Interaction ◽  
Transgenic Roots ◽  
Transfer Protein ◽  
Small Proteins

The Medicago truncatula N5 gene is induced in roots after Sinorhizobium meliloti infection and it codes for a putative lipid transfer protein (LTP), a family of plant small proteins capable of binding and transferring lipids between membranes in vitro. Various biological roles for plant LTP in vivo have been proposed, including defense against pathogens and modulation of plant development. The aim of this study was to shed light on the role of MtN5 in the symbiotic interaction between M. truncatula and S. meliloti. MtN5 cDNA was cloned and the mature MtN5 protein expressed in Escherichia coli. The lipid binding capacity and antimicrobial activity of the recombinant MtN5 protein were tested in vitro. MtN5 showed the capacity to bind lysophospholipids and to inhibit M. truncatula pathogens and symbiont growth in vitro. Furthermore, MtN5 was upregulated in roots after infection with either the fungal pathogen Fusarium semitectum or the symbiont S. meliloti. Upon S. meliloti infection, MtN5 was induced starting from 1 day after inoculation (dpi). It reached the highest concentration at 3 dpi and it was localized in the mature nodules. MtN5-silenced roots were impaired in nodulation, showing a 50% of reduction in the number of nodules compared with control roots. On the other hand, transgenic roots overexpressing MtN5 developed threefold more nodules with respect to control roots. Here, we demonstrate that MtN5 possesses biochemical features typical of LTP and that it is required for the successful symbiotic association between M. truncatula and S. meliloti.

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