scholarly journals A Laser Dissection-RNAseq Analysis Highlights the Activation of Cytokinin Pathways by Nod Factors in the Medicago truncatula Root Epidermis

2016 ◽  
Vol 171 (3) ◽  
pp. 2256-2276 ◽  
Author(s):  
Marie-Françoise Jardinaud ◽  
Stéphane Boivin ◽  
Nathalie Rodde ◽  
Olivier Catrice ◽  
Anna Kisiala ◽  
...  
Keyword(s):  
Medicago Truncatula ◽  
Nod Factors ◽  
Root Epidermis ◽  
Laser Dissection

scholarly journals Heterologous Expression of Rhizobial CelC2 Cellulase Impairs Symbiotic Signaling and Nodulation in Medicago truncatula

2018 ◽  
Vol 31 (5) ◽  
pp. 568-575 ◽  
Author(s):  
Marta Robledo ◽  
Esther Menéndez ◽  
Jose Ignacio Jiménez-Zurdo ◽  
Raúl Rivas ◽  
Encarna Velázquez ◽  
...  
Keyword(s):  
Medicago Truncatula ◽  
Cell Walls ◽  
Rhizobium Leguminosarum ◽  
Root Nodules ◽  
Root Hairs ◽  
Nod Factors ◽  
Model Legume ◽  
Ensifer Meliloti ◽  
Early Nodulin ◽  
The Impact

The infection of legume plants by rhizobia is tightly regulated to ensure accurate bacterial penetration, infection, and development of functionally efficient nitrogen-fixing root nodules. Rhizobial Nod factors (NF) have key roles in the elicitation of nodulation signaling. Infection of white clover roots also involves the tightly regulated specific breakdown of the noncrystalline apex of cell walls in growing root hairs, which is mediated by Rhizobium leguminosarum bv. trifolii cellulase CelC2. Here, we have analyzed the impact of this endoglucanase on symbiotic signaling in the model legume Medicago truncatula. Ensifer meliloti constitutively expressing celC gene exhibited delayed nodulation and elicited aberrant ineffective nodules, hampering plant growth in the absence of nitrogen. Cotreatment of roots with NF and CelC2 altered Ca2+ spiking in root hairs and induction of the early nodulin gene ENOD11. Our data suggest that CelC2 alters early signaling between partners in the rhizobia-legume interaction.

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 Strain-Ecotype Specificity in Sinorhizobium meliloti-Medicago truncatula Symbiosis Is Correlated to Succinoglycan Oligosaccharide Structure

2007 ◽  
Vol 189 (21) ◽  
pp. 7733-7740 ◽  
Author(s):  
Senay Simsek ◽  
Tuula Ojanen-Reuhs ◽  
Samuel B. Stephens ◽  
Bradley L. Reuhs
Keyword(s):  
Medicago Truncatula ◽  
Sinorhizobium Meliloti ◽  
Donor Strain ◽  
Factor Activity ◽  
Nod Factors ◽  
Strain Specificity ◽  
Oligosaccharide Structure ◽  
Nod Factor ◽  
Structural Nature ◽  
Molecular Signals

ABSTRACT Molecular signals, including Nod factors and succinoglycan, are necessary for the establishment of nitrogen-fixing nodules (Fix+) in Medicago truncatula-Sinorhizobium meliloti symbiosis. This report shows that M. truncatula-S. meliloti interactions involve ecotype-strain specificity, as S. meliloti Rm41 and NRG247 are Fix+ (compatible) on M. truncatula A20 and Fix− (incompatible) on M. truncatula A17, the Fix phenotypes are reversed with S. meliloti NRG185 and NRG34, and there is a correlation between the host specificity and succinoglycan oligosaccharide structure. S. meliloti NRG185 produces oligosaccharides that are almost fully succinylated, with two succinate groups per subunit, whereas the oligosaccharides produced by S. meliloti Rm41 include many nonsuccinylated subunits, as well as subunits with a single succinate group and others with malate. The results of this study demonstrated the following: (i) incompatibility is not a consequence of an avirulence factor or lack of Nod factor activity; (ii) the Fix+ phenotypes are succinoglycan dependent; (iii) there is structural variability in the succinoglycan oligosaccharide populations between S. meliloti strains; (iv) the structural nature of the succinoglycan oligosaccharides is correlated to compatibility; most importantly, (v) an S. meliloti Rm41 derivative, carrying exo genes from an M. truncatula A17-compatible strain, produced a modified population of succinoglycan oligosaccharides (similar to the donor strain) and was Fix+ on A17.

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 Nod Factors Alter the Microtubule Cytoskeleton in Medicago truncatula Root Hairs to Allow Root Hair Reorientation

2005 ◽  
Vol 18 (11) ◽  
pp. 1195-1204 ◽  
Author(s):  
Björn J. Sieberer ◽  
Antonius C. J. Timmers ◽  
Anne Mie C. Emons
Keyword(s):  
Medicago Truncatula ◽  
Root Hair ◽  
Tip Growth ◽  
Root Hairs ◽  
High Density ◽  
Nod Factors ◽  
Microtubule Cytoskeleton ◽  
Nod Factor ◽  
Set Up ◽  
Drug Studies

The microtubule (MT) cytoskeleton is an important part of the tip-growth machinery in legume root hairs. Here we report the effect of Nod factor (NF) on MTs in root hairs of Medicago truncatula. In tip-growing hairs, the ones that typically curl around rhizobia, NF caused a subtle shortening of the endoplasmic MT array, which recovered within 10 min, whereas cortical MTs were not visibly affected. In growth-arresting root hairs, endoplasmic MTs disappeared shortly after NF application, but reformed within 20 min, whereas cortical MTs remained present in a high density. After NF treatment, growth-arresting hairs were swelling at their tips, after which a new outgrowth formed that deviated with a certain angle from the former growth axis. MT depolymerization with oryzalin caused a growth deviation similar to the NF; whereas, combined with NF, oryzalin increased and the MT-stabilizing drug taxol suppressed NF-induced growth deviation. The NF-induced disappearance of the endoplasmic MTs correlated with a loss of polar cytoarchitecture and straight growth directionality, whereas the reappearance of endoplasmic MTs correlated with the new set up of polar cytoarchitecture. Drug studies showed that MTs are involved in determining root hair elongation in a new direction after NF treatment.

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