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Introduction
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December 1994 - present
Publications
Publications (101)
Auxin Response Factors (ARFs) constitute a large family of transcription factors that mediate auxin-regulated developmental programs in plants. ARF2, ARF3, and ARF4 are post-transcriptionally regulated by the microRNA390 (miR390)/trans-acting small interference RNA 3 (TAS3) module through the action of TAS3-derived trans
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acting small interfering...
Organogenesis of legume root nodules begins with the nodulation factor-dependent stimulation of compatible root cells to initiate divisions, signifying an early nodule primordium formation event. This is followed by cellular differentiation, including cell expansion and vascular bundle formation, and we previously showed that Lotus japonicus NF-YA1...
Advances in deciphering the functional architecture of eukaryotic genomes have been facilitated by recent breakthroughs in sequencing technologies, enabling a more comprehensive representation of genes and repeat elements in genome sequence assemblies, as well as more sensitive and tissue-specific analyses of gene expression. Here we show that PacB...
The formation of nitrogen-fixing nodules in legumes involves the initiation of synchronized programs in the root epidermis and cortex to allow rhizobial infection and nodule development. In this study, we provide evidence that symplastic communication, regulated by callose turnover at plasmodesmata (PD), is important for coordinating nodule develop...
Despite the importance of plant-plant interactions on crop yield and plant community dynamics, our understanding of the genetic and molecular bases underlying natural variation of plant-plant interactions is largely limited in comparison to other types of biotic interactions. By listing 63 QTL mapping and global gene expression studies based on pla...
Promoters with tissue-specific activity are very useful to address cell-autonomous and non cell autonomous functions of candidate genes. Although this strategy is widely used in Arabidopsis thaliana, its use to study tissue-specific regulation of root symbiotic interactions in legumes has only started recently. Moreover, using tissue specific promo...
Thin section profile of GUS activity in LaSCR1:GUS Medicago truncatula nodules.
Root cross sections showing GUS activity driven by the LaSCR1 promoter fusions in nodules of M. truncatula. GUS staining is shown in blue. 10 μm cross-sections were counter stained with ruthenium red. p: pericycle, en: endodermis. Bar = 100 μm.
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Primers used for Golden Gate cloning.
(XLSX)
Plant NF-Y transcription factors control a wide array of biological functions enabling appropriate reproductive and developmental processes as well as adaptation to various abiotic and biotic environments. In Medicago truncatula, MtNF-YA1 was previously identified as a key determinant for nodule development and establishment of rhizobial symbiosis....
NF-Ys are heterotrimeric transcription factors composed by the NF-YA, NF-YB and NF-YC subunits. In plants, NF-Y subunits are encoded by multigene families whose members show structural and functional diversifications. An increasing number of NF-Y genes has been shown to play key roles during different stages of root nodule and arbuscular mycorrhiza...
Legumes develop symbiotic interactions with rhizobial bacteria to form nitrogen-fixing nodules. Bacterial Nod factors (NFs) and plant regulatory pathways modulating NF signalling control rhizobial infections and nodulation efficiency. Here we show that gibberellin (GA) signalling mediated by DELLA proteins inhibits rhizobial infections and controls...
Supplementary Figures 1-8, Supplementary Tables 1-5
Biological nitrogen fixation in legumes occurs in nodules that are initiated in the root cortex following Nod factor recognition at the root surface, and this requires coordination of diverse developmental programs in these different tissues. We show that while early Nod factor signaling associated with calcium oscillations is limited to the root s...
The endosymbiotic association between legumes and soil bacteria called rhizobia leads to the formation of a new root-derived organ called the nodule in which differentiated bacteria convert atmospheric nitrogen into a form that can be assimilated by the host plant. Successful root infection by rhizobia and nodule organogenesis require the activatio...
Background
Legume roots show a remarkable plasticity to adapt their architecture to biotic and abiotic constraints, including symbiotic interactions. However, global analysis of miRNA regulation in roots is limited, and a global view of the evolution of miRNA-mediated diversification in different ecotypes is lacking.
Results
In the model legume Me...
Legume root nodules are induced by N-fixing rhizobium bacteria that are hosted in an intracellular manner. These nodules are formed by reprogramming differentiated root cells. The model legume Medicago truncatula forms indeterminate nodules with a meristem at their apex. This organ grows by the activity of the meristem that adds cells to the differ...
During endosymbiotic interactions between legume plants and nitrogen-fixing rhizobia, successful root infection by bacteria and nodule organogenesis requires the perception and transduction of bacterial lipo-chitooligosaccharidic signal called Nod Factor (NF). NF perception in legume roots leads to the activation of an early signaling pathway and o...
Transcription factors are DNA binding proteins that regulate gene expression. The nitrogen fixing symbiosis established between legume plants and soil bacteria is a complex interaction, in which plants need to integrate signals derived from the symbiont and the surrounding environment to initiate the developmental program of nodule organogenesis an...
A C subunit of the heterotrimeric nuclear factor Y (NF-YC1) was shown to play a key role in nodule organogenesis and bacterial infection during the nitrogen fixing symbiosis established between Phaseolus vulgaris (common bean) and Rhizobium etli. In order to identify other proteins involved in this process, we used the yeast two hybrid system to sc...
Symbiosis between legume plants and soil rhizobia culminates in the formation of a novel root organ, the ‘nodule’, containing
bacteria differentiated as facultative nitrogen-fixing organelles. MtNF-YA1 is a Medicago truncatula CCAAT box-binding transcription factor (TF), formerly called HAP2-1, highly expressed in mature nodules and required for
no...
ABSTRACT Rhizobial Nodulation Factors (NF) activate a specific signaling pathway in Medicago truncatula root hairs (RHs) that involves the complex interplay of NSP1/NSP2 GRAS and ERN1 ERF transcription factors (TFs) to achieve full ENOD11 transcription. ERN1 acts as a direct transcriptional regulator of ENOD11 through the activation of the NF-respo...
Transcription factors belonging to the CCAAT-box binding factor family (also known as the Nuclear Factor Y) are present in all higher eukaryotes. Studies in plants have revealed that each subunit of this heterotrimeric transcription factor is encoded by a gene belonging to a multigene family allowing a considerable modularity. In this review, we fo...
Most land plants live symbiotically with arbuscular mycorrhizal fungi. Establishment of this symbiosis requires signals produced by both partners: strigolactones in root exudates stimulate pre-symbiotic growth of the fungus, which releases lipochito-oligosaccharides (Myc-LCOs) that prepare the plant for symbiosis. Here, we have investigated the eve...
Cross comparison of differentially regulated genes found in different nodule samples compared to non-inoculated roots.
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Search of co-regulated transcription factors using the Medicago truncatula gene atlas data.
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List of primers used for quantitative RT-PCR analyses.
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list of 16kPlus reporters scored as differentially regulated in nodules, as compared to non inoculated, nitrogen-starved roots.
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List of genes classified by MapMan as related to heme (hemoglobin genes), phenylpropanoids and flavonoids.
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Example of a WRKY transcription factor gene from the exo1 regulation class activated both in nodules and pathogenic conditions. Gene up-regulated in wild type and mutant nodules ([19][20], this study) as well as M. truncatula plants treated by yeast elicitor [68] or challenged with the bacterial pathogen Pseudomonas syringae [103].
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Use of the Legoo knowledge base to search for possible expression of nodule-associated regulators in other conditions.
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Examples of multigene families containing root-expressed genes and nodule-associated genes.
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list of putative regulator genes scored as differentially regulated in nodules when compared to non inoculated, nitrogen-starved roots.
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Quantitative RT-PCR analyses in root samples.
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Many genes which are associated with root nodule development and activity in the model legume Medicago truncatula have been described. However information on precise stages of activation of these genes and their corresponding transcriptional regulators is often lacking. Whether these regulators are shared with other plant developmental programs als...
Arbuscular mycorrhiza (AM) is a root endosymbiosis between plants and glomeromycete fungi. It is the most widespread terrestrial plant symbiosis, improving plant uptake of water and mineral nutrients. Yet, despite its crucial role in land ecosystems, molecular mechanisms leading to its formation are just beginning to be unravelled. Recent evidence...
Remorin proteins have been hypothesized to play important roles during cellular signal transduction processes. Induction of some members of this multigene family has been reported during biotic interactions. However, no roles during host-bacteria interactions have been assigned to remorin proteins until now. We used root nodule symbiosis between Me...
Mechanisms regulating legume root nodule development are still poorly understood, and very few regulatory genes have been cloned and characterized. Here, we describe EFD (for ethylene response factor required for nodule differentiation), a gene that is upregulated during nodulation in Medicago truncatula. The EFD transcription factor belongs to the...
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 increa...
Legumes played central roles in the development of agriculture and civilization, and today account for approximately one-third of the world's primary crop production. Unfortunately, most cultivated legumes are poor model systems for genomic research. Therefore, Medicago truncatula, which has a relatively small diploid genome, has been adopted as a...
Legume root architecture is characterized by the development of two de novo meristems, leading to the formation of lateral roots or symbiotic nitrogen-fixing nodules. Organogenesis involves networks of transcription factors, the encoding mRNAs of which are frequently targets of microRNA (miRNA) regulation. Most plant miRNAs, in contrast with animal...
MtHAP2-1 is a CCAAT-binding transcription factor from the model legume Medicago truncatula. We previously showed that MtHAP2-1 expression is regulated both spatially and temporally by microRNA169. Here we present a novel regulatory mechanism controlling MtHAP2-1 expression. Alternative splicing of an intron in the MtHAP2-1 5'leader sequence (LS) be...
Branched 1,6-1,3-beta-glucans from Phytophthora sojae cell walls represent pathogen-associated molecular patterns (PAMPs) that have been shown to mediate the activation of plant defence reactions in many legumes. In soybean, a receptor protein complex containing a high affinity beta-glucan-binding protein (GBP) was identified and investigated in de...
Forward genetics has been extremely fruitful in the recent past to identify key genes involved in the very early stages of
symbiotic signaling in model legumes. However, the number of regulatory genes, particularly transcription-factor genes, demonstrated
to play a role in the control of the formation of an infected nodule remains very limited. Tra...
Genome-wide annotation of remorins, a plant-specific protein family: evolutionary and functional perspectives
Root growth and function are determined by the action of environmental stresses through specific genes that adapt root development to these restrictive conditions. We have defined in vitro conditions affecting the growth and recovery of Medicago truncatula roots after a salt stress. A dedicated macroarray containing 384 genes, based on a large-scal...
We set up a large-scale suppression subtractive hybridization (SSH) approach to identify Medicago truncatula genes differentially expressed at different stages of the symbiotic interaction with Sinorhizobium meliloti, with a particular interest for regulatory genes. We constructed 7 SSH libraries covering successive stages from Nod factor signal tr...
In the model legume Medicago truncatula, we identified a new transcription factor of the CCAAT-binding family, MtHAP2-1, for which RNA interference (RNAi) and in situ hybridization experiments indicate a key role during nodule development, possibly by controlling nodule meristem function. We could also show that MtHAP2-1 is regulated by microRNA169...
The MtENOD11 gene from the model legume Medicago truncatula is transcriptionally activated both in response to Sinorhizobium meliloti Nod factors and throughout infection of root tissues by the nitrogen-fixing microsymbiont. To identify the regulatory sequences involved in symbiosis-related MtENOD11 expression, a series of promoter deletions drivin...
This article describes an efficient procedure to study Nod factor-induced gene expression in root hairs of the model legume
Medicago truncatula. By developing an improved method of fracturing frozen root hairs, it has been possible to obtain a highly purified root
hair fraction from M. truncatula seedlings yielding sufficient RNA for real-time quan...
In this study, we describe a large-scale expression-profiling approach to identify genes differentially regulated during the symbiotic interaction between the model legume Medicago truncatula and the nitrogen-fixing bacterium Sinorhizobium meliloti. Macro- and microarrays containing about 6,000 probes were generated on the basis of three cDNA libra...