References of "Périlleux, Claire"
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See detailTowards understanding the function of JOINTLESS gene in tomato inflorescence
Huerga Fernandez, Samuel ULg; Gómez Roldán, Maria Victoria; Orman-Ligeza, Beata ULg et al

Poster (2017, September)

The lack of fruit abscission is a trait of great agronomical value. In tomato, the jointless phenotype, referring to the lack of abscission zone (AZ) in the flower pedicel, has been obtained by two ... [more ▼]

The lack of fruit abscission is a trait of great agronomical value. In tomato, the jointless phenotype, referring to the lack of abscission zone (AZ) in the flower pedicel, has been obtained by two independent mutations, named jointless (j) and jointless-2 (j-2). The corresponding genes encode MADS-box transcription factors, as shown in 2000 for J (Mao et al. 2000) and very recently for J-2, known as SlMBP21 (Gomez-Roldan et al., 2017). Similar to the quartet model of MADS-box protein complexes regulating floral organ formation, J and J-2 interact with MADS-box partners, among which MACROCRALYX (MC), to regulate AZ formation (Liu et al. 2014). In addition to - or in connection with - AZ formation, J acts during the building of the inflorescence to regulate meristem fate. Indeed j mutants produce leafy inflorescences characterized by faster flower maturation and resumption of vegetative meristems (Périlleux et al. 2014). For these traits, j is epistatic to j-2. The involvement of J in the regulation of meristem fate is consistent with the roles of its closest homologs in Arabidopsis, AGAMOUS LIKE 24 (AGL24) and SHORT VEGETATIVE PHASE (SVP). Our goal is to identify J targets in order to unravel its multiple functions in the tomato inflorescence. [less ▲]

See detailFlowering roots: Insensitive Root Growth 1 contributes to photoperiod-induced root responses in Arabidopsis.
Orman-Ligeza, Beata ULg; Detry, Nathalie ULg; Tocquin, Pierre ULg et al

Poster (2017, September)

The capacity to perceive and respond to seasonal changes of day length is essential for flowering plants. Under favourable photoperiod, a mobile stimulus synthesized in leaves moves to the shoot apex and ... [more ▼]

The capacity to perceive and respond to seasonal changes of day length is essential for flowering plants. Under favourable photoperiod, a mobile stimulus synthesized in leaves moves to the shoot apex and triggers the expression of genes required for the transition to flower initiation. Although transition from vegetative to reproductive state also encompasses a transcriptional response in roots, the internal signalling pathways and how root system architecture adjusts to this changing status remain elusive. Here we show in Arabidopsis that root growth rate increases upon a transfer to flowering-inductive long days while remaining constant under short days. To elucidate genetic components of this response, we performed a meta-analysis of available root-growth and flowering-related arrays and selected genes with overlapping transcriptional profiles for further analyses. Loss of function in a member of the basic leucine zipper transcription factor gene family, hereafter named Insensitive Root Growth-1 (IRG1), was found to suppress photoperiod-response of root growth with no defect in flowering time. We show that sucrose, but neither glucose nor mannitol in the growth medium under long days, is needed to trigger this response. In addition, extending the photoperiod with non-photosynthetic far red light had no effect on root growth of irg-1 mutant, alike wild type Col-0. The expression level of IRG1 in the roots remains low during the daytime and peaks late at night, suggesting that this gene is regulated by the clock’s evening loop. Taken together, our results suggest that IRG1 may be involved in sucrose-mediated stimulation of root growth during the night phase in Arabidopsis. The functional characterisation of IRG1 is currently underway. [less ▲]

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See detailNatural and induced loss of function mutations in SlMBP21 MADS-box gene led to jointless-2 phenotype in tomato
Gomez Roldan, Maria Victoria; Périlleux, Claire ULg; Morin, Halima et al

in Scientific Reports (2017), 7

Abscission is the mechanism by which plants disconnect unfertilized flowers, ripe fruits, senescent or diseased organs from the plant. In tomato, pedicel abscission is an important agronomic factor that ... [more ▼]

Abscission is the mechanism by which plants disconnect unfertilized flowers, ripe fruits, senescent or diseased organs from the plant. In tomato, pedicel abscission is an important agronomic factor that controls yield and post-harvest fruit quality. Two non-allelic mutations, jointless (j) and jointless-2 (j-2), controlling pedicel abscission zone formation have been documented but only j-2 has been extensively used in breeding. J was shown to encode a MADS-box protein. Using a combination of physical mapping and gene expression analysis we identified a positional candidate, Solyc12g038510, associated with j-2 phenotype. Targeted knockout of Solyc12g038510, using CRISPR/Cas9 system, validated our hypothesis. Solyc12g038510 encodes the MADS-box protein SlMBP21. Molecular analysis of j-2 natural variation revealed two independent loss-of-function mutants. The first results of an insertion of a Rider retrotransposable element. The second results of a stop codon mutation that leads to a truncated protein form. To bring new insights into the role of J and J-2 in abscission zone formation, we phenotyped the single and the double mutants and the engineered alleles. We showed that J is epistatic to J-2 and that the branched inflorescences and the leafy sepals observed in accessions harboring j-2 alleles are likely the consequences of linkage drags. [less ▲]

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See detailLes mystères de la floraison
Périlleux, Claire ULg

Conference given outside the academic context (2017)

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See detailUsing a Structural Root System Model to Evaluate and Improve the Accuracy of Root Image Analysis Pipelines
Lobet, Guillaume; Koevoets, Iko; Noll, Manuel ULg et al

in Frontiers in Plant Science (2017), 8

Root system analysis is a complex task, often performed with fully automated image analysis pipelines. However, the outcome is rarely verified by ground-truth data, which might lead to underestimated ... [more ▼]

Root system analysis is a complex task, often performed with fully automated image analysis pipelines. However, the outcome is rarely verified by ground-truth data, which might lead to underestimated biases. We have used a root model, ArchiSimple, to create a large and diverse library of ground-truth root system images (10,000). For each image, three levels of noise were created. This library was used to evaluate the accuracy and usefulness of several image descriptors classically used in root image analysis softwares. Our analysis highlighted that the accuracy of the different traits is strongly dependent on the quality of the images and the type, size and complexity of the root systems analysed. Our study also demonstrated that machine learning algorithms can be trained on a synthetic library to improve the estimation of several root system traits. Overall, our analysis is a call to caution when using automatic root image analysis tools. If a thorough calibration is not performed on the dataset of interest, unexpected errors might arise, especially for large and complex root images. To facilitate such calibration, both the image library and the different codes used in the study have been made available to the community. [less ▲]

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See detailInflorescence development in tomato
Périlleux, Claire ULg

Scientific conference (2016, December 02)

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See detailMaize plants can enter a standby mode to cope with chilling stress
Riva-Roveda, Laetitia ULg; Escale, Brigitte; Giauffret, Catherine et al

in BMC Plant Biology (2016), 16

Background European Flint maize inbred lines are used as a source of adaptation to cold in most breeding programs in Northern Europe. A deep understanding of their adaptation strategy could thus provide ... [more ▼]

Background European Flint maize inbred lines are used as a source of adaptation to cold in most breeding programs in Northern Europe. A deep understanding of their adaptation strategy could thus provide valuable clues for further improvement, which is required in the current context of climate change. We therefore compared six inbreds and two derived Flint x Dent hybrids for their response to one-week at low temperature (10°C day/7 or 4°C night) during steady-state vegetative growth. Results Leaf growth was arrested during chilling treatment but recovered fast upon return to warm temperature, so that no negative effect on shoot biomass was measured. Gene expression analyses of the emerging leaf in the hybrids suggest that plants maintained a ‘ready-to-grow’ state during chilling since cell cycle genes were not differentially expressed in the division zone and genes coding for expansins were on the opposite up-regulated in the elongation zone. In photosynthetic tissues, a strong reduction in PSII efficiency was measured. Chilling repressed chlorophyll biosynthesis; we detected accumulation of the precursor geranylgeranyl chlorophyll a and down-regulation of GERANYLGERANYL REDUCTASE (GGR) in mature leaf tissues. Excess light energy was mostly dissipated through fluorescence and constitutive thermal dissipation processes, rather than by light-regulated thermal dissipation. Consistently, only weak clues of xanthophyll cycle activation were found. CO2 assimilation was reduced by chilling, as well as the expression levels of genes encoding phosphoenolpyruvate carboxylase (PEPC), pyruvate orthophosphate dikinase (PPDK), and the small subunit of Rubisco. Accumulation of sugars was correlated with a strong decrease of the specific leaf area (SLA). Conclusions Altogether, our study reveals good tolerance of the photosynthetic machinery of Northern European maize to chilling and suggests that growth arrest might be their strategy for fast recovery after a mild stress. [less ▲]

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See detailUsing a structural root system model for an in-depth assessment of root image analysis pipeline
Lobet, Guillaume ULg; Koevoets, Iko; Tocquin, Pierre ULg et al

in bioRxiv (2016)

Root system analysis is a complex task, often performed using fully automated image analysis pipelines. However, these pipelines are usually evaluated with a limited number of ground-truth root images ... [more ▼]

Root system analysis is a complex task, often performed using fully automated image analysis pipelines. However, these pipelines are usually evaluated with a limited number of ground-truth root images, most likely of limited size and complexity. We have used a root model, ArchiSimple to create a large and diverse library of ground-truth root system images (10.000). This library was used to evaluate the accuracy and usefulness of several image descriptors classicaly used in root image analysis pipelines. Our analysis highlighted that the accuracy of the different metrics is strongly linked to the type of root system analyzed (e.g. dicot or monocot) as well as their size and complexity. Metrics that have been shown to be accurate for small dicot root systems might fail for large dicots root systems or small monocot root systems. Our study also demonstrated that the usefulness of the different metrics when trying to discriminate genotypes or experimental conditions may vary. Overall, our analysis is a call to caution when automatically analyzing root images. If a thorough calibration is not performed on the dataset of interest, unexpected errors might arise, especially for large and complex root images. To facilitate such calibration, both the image library and the different codes used in the study have been made available to the community. [less ▲]

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See detailIntegrating roots into a whole plant network of flowering time genes in Arabidopsis thaliana
Bouché, Frédéric ULg; D'Aloia, Maria; Tocquin, Pierre ULg et al

in Scientific Reports (2016), 6

Molecular data concerning the involvement of roots in the genetic pathways regulating floral transition are lacking. In this study, we performed global analyses of the root transcriptome in Arabidopsis in ... [more ▼]

Molecular data concerning the involvement of roots in the genetic pathways regulating floral transition are lacking. In this study, we performed global analyses of the root transcriptome in Arabidopsis in order to identify flowering time genes that are expressed in the roots and genes that are differentially expressed in the roots during the induction of flowering. Data mining of public microarray experiments uncovered that about 200 genes whose mutations are reported to alter flowering time are expressed in the roots (i.e. were detected in more than 50% of the microarrays). However, only a few flowering integrator genes passed the analysis cutoff. Comparison of root transcriptome in short days and during synchronized induction of flowering by a single 22-h long day revealed that 595 genes were differentially expressed. Enrichment analyses of differentially expressed genes in root tissues, gene ontology categories, and cis-regulatory elements converged towards sugar signaling. We concluded that roots are integrated in systemic signaling, whereby carbon supply coordinates growth at the whole plant level during the induction of flowering. This coordination could involve the root circadian clock and cytokinin biosynthesis as a feed forward loop towards the shoot. [less ▲]

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See detailFunctional analysis of PEBP genes in root chicory (Cichorium intybus)
Saintmard, Nicolas ULg; Tocquin, Pierre ULg; Périlleux, Claire ULg

Poster (2016, June 09)

Manipulating plant architecture is key to increase crop yield. In this perspective, basic knowledge on the molecular mechanisms regulating plant growth and development will be fundamental for the future ... [more ▼]

Manipulating plant architecture is key to increase crop yield. In this perspective, basic knowledge on the molecular mechanisms regulating plant growth and development will be fundamental for the future of agriculture. Recent progress indicates that a family of plant genes, homologous to POSPHADITYLETHANOLAMINE-BINDING PROTEINS (PEBP) in other eukaryotes, plays critical roles in controlling shoot development traits such as branching, flowering, bud dormancy or tuberization. Very little is known however on the functions of these genes in root development. The current research will attempt to answer this question in the case of Cichorium intybus, a biannual plant cultivated for the extraction of inulin (a polymer of fructose) from its root. Functional analyses will include expression kinetics, complementation tests in Arabidopsis mutants and creation of PEBP- overexpressing or silencing chicory plants. The preliminary steps of the project are the identification of PEBP genes in chicory by in silico analyses, the determination of the time of the storage root initiation and the establishment of a regeneration protocol for the genetic transformation. [less ▲]

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See detailRhizosecreted proteases inhibition for the improvement of recombinant protein production in Arabidopsis thaliana
Lallemand, Jérôme ULg; Périlleux, Claire ULg; Tocquin, Pierre ULg

Poster (2016, April)

Plant-based biopharmaceuticals have gained a lot of interest in the past decade due to their reduced cost and relative safety compared to mammalian cell cultures. While the first plant-made recombinant ... [more ▼]

Plant-based biopharmaceuticals have gained a lot of interest in the past decade due to their reduced cost and relative safety compared to mammalian cell cultures. While the first plant-made recombinant proteins are now reaching the market, the production systems still need improvements to maximize their competitiveness. Optimizing production hosts requires the identification and subsequent inhibition of the most active endogenous peptidases, proteolysis being one of the main factors limiting yields. The aim of our study was to identify root-secreted proteases of Arabidopsis thaliana involved in target protein degradation (BSA) and inhibit them in vivo. Biochemical analyses identified serine proteases as the main class responsible for BSA degradation. An RT-qPCR experiment led to the choice of the serine protease gene SBT4.12 and its homologs as targets for an amiRNA-mediated silencing approach. Arabidopsis amiRNA-expressing lines showed lower levels of expression for SBT4.12 and reduced proteolytic activity in their rhizosecreted extracts. Crossing these lines with recombinant protein producing lines could lead to an improved production platform for proteins of interest. [less ▲]

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See detailFLOR-ID: an interactive database of flowering-time gene networks in Arabidopsis thaliana
Bouché, Frédéric ULg; Lobet, Guillaume ULg; Tocquin, Pierre ULg et al

in Nucleic Acids Research (2016), 44(Database), 11671171

Flowering is a hot topic in Plant Biology and important progress has been made in Arabidopsis thaliana toward unravelling the genetic networks involved. The increasing complexity and the explosion of ... [more ▼]

Flowering is a hot topic in Plant Biology and important progress has been made in Arabidopsis thaliana toward unravelling the genetic networks involved. The increasing complexity and the explosion of literature however require development of new tools for information management and update. We therefore created an evolutive and interactive database of flowering time genes, named FLOR-ID (Flowering-Interactive Database), that is available freely at http://www.flor-id.org. The hand-curated database contains information on 306 genes and links to 1595 publications gathering the work of more than 4500 authors. Gene function and interactions within the flowering pathways were inferred from the analysis of related publications, included in the database and translated into interactive manually drawn snapshots. [less ▲]

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See detailRBOH-mediated ROS production facilitates lateral root emergence in Arabidopsis
Orman-Ligeza, Beata ULg; Parizot, Boris; de Rycke, Riet et al

in Development (2016)

Lateral root (LR) emergence represents a highly coordinated process in which the plant hormone auxin plays a central role. Reactive oxygen species (ROS) have been proposed to function as important signals ... [more ▼]

Lateral root (LR) emergence represents a highly coordinated process in which the plant hormone auxin plays a central role. Reactive oxygen species (ROS) have been proposed to function as important signals during auxin-regulated LR formation, however their mode of action is poorly understood. Here, we report that Arabidopsis roots exposed to ROS show increased LR numbers due to the activation of LR pre-branch sites and LR primordia (LRP). Strikingly, ROS treatment can also restore LR formation in pCASP1:shy2-2 and aux1 lax3 mutant lines in which auxin-mediated cell wall accommodation and remodeling in cells overlying the sites of LR formation is disrupted. Specifically, ROS are deposited in the apoplast of these cells during LR emergence, following a spatio-temporal pattern that overlaps the combined expression domains of extracellular ROS donors of the RESPIRATORY BURST OXIDASE HOMOLOGS (RBOH). We also show that disrupting (or enhancing) expression of RBOH in LRP and/or overlying root tissues decelerates (or accelerates) the development and emergence of LRs. We conclude that RBOH-mediated ROS production facilitates LR outgrowth by promoting cell wall remodeling of overlying parental tissues. [less ▲]

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See detailModeling inflorescence development in tomato
Périlleux, Claire ULg; Lobet, Guillaume ULg; Tocquin, Pierre ULg

Conference (2015, June)

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See detailGènes candidats dans un modèle de développement de l'inflorescence de tomate
Périlleux, Claire ULg

Scientific conference (2015, June)

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See detailExtracellular peptidase hunting for improvement of protein production in plant cells and roots
Lallemand, Jérôme ULg; Bouché, Frédéric ULg; Desiron, Carole et al

Poster (2015, June)

Plant-based biopharmaceuticals have gained a lot of interest in the past decade due to their reduced cost and relative safety compared to mammalian cell cultures. While the first plant-made recombinant ... [more ▼]

Plant-based biopharmaceuticals have gained a lot of interest in the past decade due to their reduced cost and relative safety compared to mammalian cell cultures. While the first plant-made recombinant proteins are now reaching the market, the production systems still need improvements to maximize their competitiveness, proteolysis being one of the main factors limiting the yields. Identifying and inhibiting in vivo endogenous proteases involved in the degradation of recombinant proteins could then lead to a significant increase in production yields. In this study, we focused on two different production systems in Arabidopsis thaliana: rhizosecretion and cell suspensions. Extracellular proteases of both systems were used in vitro to study the conditions of target protein degradation (Bovine Serum Albumine, BSA). First, proteases from both systems degrade BSA at both acidic and neutral-to-basic pH conditions. Then, serine and metallopeptidases were shown to be the main protease classes responsible for BSA degradation by rhizosecreted proteomes or extracellular cell culture media, respectively. Finally, the biochemical tests were coupled to a bioinformatics analysis of publicly available transcriptomic data, in order to reduce the number of the proteases most likely involved in BSA degradation. Using this method, only five serine proteases and two metallopeptidases remain candidates for an amiRNA-mediated in vivo inhibition. [less ▲]

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See detailPlant Image Analysis tools. Current trends and limitations
Lobet, Guillaume ULg; Draye, Xavier; Périlleux, Claire ULg

Scientific conference (2015, April)

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See detailGenetic Control of Flowering Time in Arabidopsis: an Interactive Database
Bouché, Frédéric ULg; Lobet, Guillaume ULg; Tocquin, Pierre ULg et al

Poster (2015, March 12)

The transition to flowering is an essential step of the plant life cycle that is tightly controlled by both endogenous and environmental cues. Its regulation is extremely complex and involves hundreds of ... [more ▼]

The transition to flowering is an essential step of the plant life cycle that is tightly controlled by both endogenous and environmental cues. Its regulation is extremely complex and involves hundreds of genes that are part of highly interconnected pathways. Our knowledge of the molecular mechanisms governing the floral induction of Arabidopsis thaliana increases quickly and a significant number of reviews are published every year on this topic. However, most of them focus on a single pathway without highlighting the interconnections existing between them. Furthermore, those reviews become rapidly outdated, since our comprehension of the genetic control of flowering time evolves continuously. Hence, we believe that the current landscape of flowering time research in Arabidopsis misses an exhaustive repository of the genes involved in the control of flowering and their regulatory pathways. Here, we present a new interactive resource built around a curated database of the flowering time genes that brings together multiple pieces of information such as their function, the flowering time phenotype of mutants and overexpressing lines, the related key publications, etc. Our website thus gives access to a curated and exhaustive list of the genes involved in the regulation of flowering time in Arabidopsis as well as the regulatory pathways controlling their expression. Because of its flexibility, the database is highly dynamic and will be periodically updated with the future breakthroughs in this domain. [less ▲]

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