Agnès Lepage's research while affiliated with Institut national supérieur des sciences agronomiques, de l'alimentation et de l'environnement and other places

Publications (14)

Article
Full-text available
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...
Article
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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...
Data
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. (PDF)
Article
Full-text available
Nod factors (NF) are lipochitooligosaccharidic signal molecules produced by rhizobia, which play a key role in the rhizobium-legume symbiotic interaction. In this study, we analyzed the gene expression reprogramming induced by purified NF (4h and 24h of treatment) in the root epidermis of the model legume Medicago truncatula. Tissue-specific transc...
Article
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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...
Article
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...
Article
Full-text available
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...
Article
Full-text available
This study aimed at defining the role of a basic helix–loop–helix (bHLH) transcription factor gene from Medicago truncatula, MtbHLH1, whose expression is upregulated during the development of root nodules produced upon infection by rhizobia bacteria. We used MtbHLH1 promoter::GUS fusions and quantitative reverse-transcription polymerase chain reac...

Citations

... In addition, using the transcriptomic data for M. truncatula at 24 and 48 h, as well as 3, 4, 5, and 7 dai [16] ( Figure S2), the transcription levels of homologous genes of MADS-domain/AGL family were estimated as well as their localization in mature nodules ( Figure S3). Analysis has shown the highest level of activation in response to inoculation for the MtMADS1 (the closest homologue of Psat2g080200 (PsSVP-like) ( Figure S3A) up to 7 dai, and its high expression level in the nodules ( Figure S3B This resulted in the identification of an additional Psat2g080200 gene encoding MADS-domain/AGL transcription factor, which is the closest homologue of SHORT VEGETATIVE PHASE-like (PvSVP-like, 87.90% of identity) in P. vulgaris, and MtMADS1 [54,55]. Previously, among differentially expressed genes, we found the Psat0s133g0120 gene, the closest homologue of LjSTY1 and LjSTY7 genes from L. japonicus [36]. ...
... For cortical expression, we assembled a GUS reporter driven by the Arabidopsis thaliana endopeptidase PEP-promoter (ProPEP) that has been previously used in Medicago. 19,20 We confirmed cortical activation of this promoter with the GUS signal being excluded from the epidermis and occasionally weaker in the outer compared with inner cortical cell layers ( Figures S4B-S4B%). When silencing NPL expression using a ProPEP-NPL-RNAi construct, we observed that most ITs successfully prolonged through the RHs (42/61; Figure 3M), whereas a large proportion of them aborted in the root cortex (32/48; Figure 3N). ...
... During the infection process and nodule initiation, regulation of plant hormonal status is one of the major targets of symbiotic signaling. Numerous studies have shown that the activation of cytokinin signaling in response to Nod factor perception [4][5][6][7][8][9][10][11] followed by a local increase in auxin in the cortex due to the inhibition of polar auxin transport (PAT) and auxin biosynthesis stimulation may be crucial for the control of nodule primordium formation [12][13][14][15][16][17][18][19][20][21]. Legumes belonging to the inverted repeat-lacking clade (IRLC) such as Medicago truncatula, Pisum sativum, and Vicia sativa form indeterminate nodules with persistent apical meristem. ...
... 8.14 Nuclear factor Y Nuclear factor Y (NF-Y) belongs to the heterotrimeric TF family, made up of three individual proteins, NF-YA, NF-YB, and NF-YC, to regulate the expression of the target gene by binding to the CCAAT element in its promoter (Baudin et al., 2015). Initially, a dimer of NF-YB and NF-YC form in the cytosol, followed by the association of the third subunit, NF-YA, to form a mature, heterotrimeric TF complex. ...
... Target genes of NIN encode proteins such as NODULATION PECTATE LYASE (LjNPL), an enzyme that mediates cell wall degradation during infection thread initiation (Xie et al., 2012;Liu et al., 2019a); SCAR-Nodulation (LjSCARN), a component of the actin regulatory complex that promotes the formation of new actin filaments in root hairs during infection thread development (Qiu et al., 2015); and Nuclear Factor-YA1 (LjNF-YA1/MtNF-YA1), a transcription factor that promotes cortical cell division for nodule organogenesis (Combier et al., 2006;Soyano et al., 2013). MtNF-YA1 also regulates infection thread formation via direct activation of MtERN1 expression in M. truncatula (Laloum et al., 2014). Additionally, phytohormones are involved in root nodule symbiosis signaling (Buhian and Bensmihen, 2018;Lin et al., 2020). ...
... Analysis of plant mutants forming nodules impaired in infection by rhizobia allowed the identification of some regulators involved in the control of later stages of nodule development. As an example, analysis of M. truncatula mutants defective in the MtNF-YA1 (MtHAP2-1) gene showed that bacterial release and microRNA169 may be important for transition of the daughter cells to endoreduplication and subsequent bacterial infection [27,28]. It is proposed that microRNA169 may restrict the MtNF-YA1 (MtHAP2-1) expression to the nodule meristematic zone that is essential for the differentiation of cells in the infection zone of the nodule [27]. ...
... To date, a large number of bHLH family genes has been identified from various plant species, including Arabidopsis [7], poplar [8], rice [9], apple [10], grapes [11], peach [12], tomato [13], pear [14] and so on. The bHLH TFs have been reported to act as important regulators involved in the regulation of various plant developmental and metabolic processes, such as nodule vascular patterning [15], root hair formation [16], stomata and root development [17,18], trichome initiation [19], leaf senescence [20], seed germination [21], flowering regulation [22], hormone metabolism [23,24], biosynthesis of alkaloid, nicotine, tryptophan [25], flavonoid and anthocyanin [26,27]. In addition, previous reports have revealed that bHLH TFs also play important roles in regulating plant responses to drought and other abiotic stresses. ...