Plant and Seed Biology
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Rescooped by Loïc Lepiniec from Plant Sciences
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Domesticated transposable elements regulate imprinted genes and drive endosperm development - Claudia Köhler - On line SPS seminar can be viewed here

Domesticated transposable elements regulate imprinted genes and drive endosperm development - Claudia Köhler - On line SPS seminar can be viewed here | Plant and Seed Biology | Scoop.it

Claudia Köhler(Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, Uppsala, Sweden)

Genomic imprinting is an epigenetic phenomenon altering the activity of parental alleles depending on their parent-of-origin. In flowering plants, imprinting is mainly confined to the endosperm, an embryo supportive tissue similar to the placenta in mammals. Epigenetic imprints are established during gamete formation; however, the determining factors for imprinting establishment remain obscure. We identified the MADS-box transcription factor PHERES1 as master regulator of imprinted gene expression in the flowering plant Arabidopsis thaliana, especially of paternally expressed genes, which have been previously implicated in endosperm development. Control of imprinted gene expression by PHERES1 is mediated by parental asymmetry of epigenetic modifications in PHERES1 DNA-binding sites, conferring different accessibilities to maternal and paternal alleles. Importantly, the DNA-binding motifs used by PHERES1 to access gene promoters are carried by RC/Helitron transposable elements, providing an example of molecular domestication of these elements. Thus, transposable elements are intrinsically linked to imprinting and endosperm development, not only by enforcing specific epigenetic landscapes, but also by serving as important sources of cis-regulatory elements.


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From Bench to Bountiful Harvests.  Multinational Arabidopsis Steering Committee (MASC) Annual Report 2019/2020

From Bench to Bountiful Harvests.  Multinational Arabidopsis Steering Committee (MASC) Annual Report 2019/2020 | Plant and Seed Biology | Scoop.it

This can also be downloaded here:
http://arabidopsisresearch.org/images/publications/mascreports/MASC_Report_2020_Online_.pdf

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The impact of synthetic biology for future agriculture and nutrition

The impact of synthetic biology for future agriculture and nutrition | Plant and Seed Biology | Scoop.it
Global food production needs to be increased by 70% to meet demands by 2050. Current agricultural practices cannot cope with this pace and furthermore are not ecologically sustainable. Innovative solutions are required to increase productivity and nutritional quality. The interdisciplinary field of synthetic biology implements engineering principles into biological systems and currently revolutionizes fundamental and applied research. We review the diverse spectrum of synthetic biology applications that started impacting plant growth and quality. We focus on latest advances for synthetic carbon-conserving pathways in vitro and in planta to improve crop yield. We highlight strategies improving plant nutrient usage and simultaneously reduce fertilizer demands, exemplified with the engineering of nitrogen fixation in crops or of synthetic plant-microbiota systems. Finally, we address engineering approaches to increase crop nutritional value as well as the use of photoautotrophic organisms as autonomous factories for the production of biopharmaceuticals and other compounds of commercial interest.


Via Jean-Michel Ané
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Plants with genetically encoded autoluminescence

Plants with genetically encoded autoluminescence | Plant and Seed Biology | Scoop.it
Autoluminescent plants engineered to express a bacterial bioluminescence gene cluster in plastids have not been widely adopted because of low light output. We engineered tobacco plants with a fungal bioluminescence system that converts caffeic acid (present in all plants) into luciferin and report self-sustained luminescence that is visible to the naked eye. Our findings could underpin development of a suite of imaging tools for plants. Luminescence is engineered in whole plants, without an exogenous substrate, using a fungal gene cluster.

Via Herman Höfte
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A Pan-plant Protein Complex Map Reveals Deep Conservation and Novel Assemblies

A Pan-plant Protein Complex Map Reveals Deep Conservation and Novel Assemblies | Plant and Seed Biology | Scoop.it

Highlights

  • A global snapshot of protein organization in plants from deep proteomics profiling
  • Biochemical fractionation reveals stable protein complexes conserved across plants
  • Many observed complexes have previously only been inferred in plants by gene content
  • Known molecular modules are elaborated in plants with novel subunits and organization

Summary

Plants are foundational for global ecological and economic systems, but most plant proteins remain uncharacterized. Protein interaction networks often suggest protein functions and open new avenues to characterize genes and proteins. We therefore systematically determined protein complexes from 13 plant species of scientific and agricultural importance, greatly expanding the known repertoire of stable protein complexes in plants. By using co-fractionation mass spectrometry, we recovered known complexes, confirmed complexes predicted to occur in plants, and identified previously unknown interactions conserved over 1.1 billion years of green plant evolution. Several novel complexes are involved in vernalization and pathogen defense, traits critical for agriculture. We also observed plant analogs of animal complexes with distinct molecular assemblies, including a megadalton-scale tRNA multi-synthetase complex. The resulting map offers a cross-species view of conserved, stable protein assemblies shared across plant cells and provides a mechanistic, biochemical framework for interpreting plant genetics and mutant phenotypes.
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Modulation of auxin formation by the cytosolic phenylalanine biosynthetic pathway

Modulation of auxin formation by the cytosolic phenylalanine biosynthetic pathway | Plant and Seed Biology | Scoop.it

In plants, phenylalanine biosynthesis occurs via two compartmentally separated pathways. Overexpression of petunia chorismate mutase 2 (PhCM2), which catalyzes the committed step of the cytosolic pathway, increased flux in cytosolic phenylalanine biosynthesis, but paradoxically decreased the overall levels of phenylalanine and phenylalanine-derived volatiles. Concomitantly, the levels of auxins, including indole-3-acetic acid and its precursor indole-3-pyruvic acid, were elevated. Biochemical and genetic analyses revealed the existence of metabolic crosstalk between the cytosolic phenylalanine biosynthesis and tryptophan-dependent auxin biosynthesis mediated by an aminotransferase that uses a cytosolic phenylalanine biosynthetic pathway intermediate, phenylpyruvate, as an amino acceptor for auxin formation.

 

In plants, the cytosolic phenylalanine biosynthetic intermediate phenylpyruvate can serve as an amino acceptor in tryptophan-dependent auxin biosynthesis, thus facilitating crosstalk between these two distinct primary metabolic pathways.

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Doctoral School of Plant Sciences, the competition is open! deadline 28 May 2020! 

Doctoral School of Plant Sciences, the competition is open! deadline 28 May 2020!  | Plant and Seed Biology | Scoop.it
 

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L’Académie d’agriculture de France publie un avis sur la "Réécriture du génome, éthique et confiance", dans le cas des plantes cultivées, de la forêt et des animaux d’élevage

L’Académie d’agriculture de France publie un avis sur la "Réécriture du génome, éthique et confiance", dans le cas des plantes cultivées, de la forêt et des animaux d’élevage | Plant and Seed Biology | Scoop.it
Paris, le 12 mars 2020

L’avis sur la « Réécriture du génome, éthique et confiance » a été approuvé par séance plénière de l’Académie d’agriculture de France le 8 janvier 2020 par 85 voix pour, 7 contre et 12 abstentions (soit plus de 80% des votants). A l’issue du vote, une opinion différente « Point de vue d’académiciens » signé par 15 membres s’est manifestée pour aller au-delà de la position adoptée.

 

Paul Vialle et Bertrand Hervieu, rapporteurs du groupe de travail, ont animé les débats sur ce thème très sensible, ayant abouti à la rédaction de l’avis. Au terme de ces travaux, l’Académie énonce 8 recommandations selon 4 principes directeurs pour guider l‘action :

  • Agir de façon responsable,
  • Respecter le principe de précaution,
  • Associer largement le public. Informer. Agir de façon transparente,
  • Procéder à des réévaluations régulières.

 

L’avis analyse ces technologies de réécriture du génome (dont celle de CRISPR Cas 9), plus précises, plus rapides, moins chères que les méthodes antérieures, mais dans certains cas sans introduction d’ADN extérieur, donc impossibles à distinguer par la suite. La question éthique divise : faut-il penser le génome comme le support d’un programme que l’on peut manipuler, ou comme la mémoire d’une longue évolution qui permet à la cellule d’explorer des solutions si on lui en laisse le temps ? Une réponse consiste à élargir le débat aux diverses parties prenantes, impliquant citoyens et consommateurs, pour hiérarchiser démocratiquement les priorités, en ouvrant sans réticence les dossiers à la société. Après analyse d’exemples concrets très divers, il ressort que chaque cas est singulier, et que cette diversité doit être prise en considération tant au niveau des bénéfices que des risques éventuels.

Pendant les travaux de l’Académie, la Cour de justice de l’Union européenne (CJUE), sur la base de la directive européenne 2001-18, a rendu une décision classant les produits issus de ces techniques parmi les OGM, indépendamment de l’évolution scientifique de ces 20 dernières années. Depuis, le Conseil d’Etat a suivi cette décision.

 

L’Académie affirme le bien-fondé d’utiliser ces techniques pour des objectifs de recherche cognitive, comme c’est déjà le cas en santé humaine. Elle est convaincue que leurs applications font partie des solutions pour contribuer à relever les défis mondiaux urgents actuels : biodiversité, changement climatique, évolution de la population mondiale, et qu’elles peuvent s’inscrire dans les priorités politiques actuelles, comme l’agroécologie ou le bien-être animal.

 

L’Académie maintient la nécessité d’une autorisation préalable mais avec des dossiers mieux calibrés et un suivi des autorisations limitées dans le temps et révocables, auxquelles il pourrait être mis fin sans irréversibilité. L’article 7 de la directive 2001-18 instaurant une procédure différenciée - apparemment jamais utilisée – peut alors fournir, sans changer la législation actuelle, un cadre juridique à tester. Pour éviter le décalage entre science et droit, l’AAF propose une révision tous les 7 ans des textes régissant ces domaines, comme pour le Conseil consultatif national d’éthique.

 

L’Académie demande avec insistance aux pouvoirs publics de sortir d’une position attentiste. Enfin, elle souhaite contribuer à cette évolution et, pour ce faire, est prête à solliciter et accompagner les législateurs, en lien avec d’autres académies françaises et européennes.

Pour lire l’avis : https://www.academie-agriculture.fr/publications/publications-academie/avis/reecriture-du-genome-ethique-et-confiance  

Pour lire le Point de vue d’Académiciens sur… : https://www.academie-agriculture.fr/publications/publications-academie/points-de-vue/reecriture-du-genome-ethique-et-confiance-les

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SPS Summer School 2020 Plant cell walls in development, plant-microbe interactions and for the bioeconomy July 5-11, 2020 – Versailles (Application deadline March 11)

SPS Summer School 2020 Plant cell walls in development, plant-microbe interactions and for the bioeconomy  July 5-11, 2020 – Versailles (Application deadline March 11) | Plant and Seed Biology | Scoop.it
 
 

The study of the cell wall is an important research frontier in plant biology. Over the past decade, the field has seen major technological and conceptual advances. In addition, the study of cell wall structure and metabolism has become an integral part of the research on plant development and the adaptation to abiotic and biotic stresses. A better knowledge of the cell wall is also essential for the optimization of lignocellulosic biomass processing procedures in the framework of the emerging bioeconomy.

 

The SPS Summer School 2020 is a one-week programme for outstanding and enthusiastic PhD students and young post-docs. It will provide them with an introduction in chemistry, biophysics, molecular and cell biology in relation to the plant cell wall.

This Summer School will bring together 16 participants from all over the world and offer them the chance to receive scientific training in an international and rather informal atmosphere, facilitating exchanges. This course will involve theoretical lectures delivered by world-class experts and hands on practical courses on state of the art technologies.

It will share some sessions with another training course, focused on lignin utilisation, organized in parallel by the EU project ZELCOR.

Download the provisional program of the Summer School

Topics and speakers

The SPS Summer School 2020 will include:

         > Theoretical modules (10 hours):

Leading scientists will hold lectures on the topics of the summer school, giving the participants a comprehensive insight into the latest research findings and identifying key open questions in the field.

“Glycobiology and cell wall structure”
Marie-Christine Ralet (Biopolymères, Interactions, Assemblages - Nantes, France)

“Lignification (and lignins), a major event of the plant kingdom”
- Catherine Lapierre (Institut Jean-Pierre Bourgin – Versailles, France)

 “Role of the cell wall in plant/micro-organism interaction”
Antonio Molina (Centro de Biotecnología y Genómica de Plantas – Madrid, Spain)
- Aline Voxeur (Institut Jean-Pierre Bourgin – Versailles, France)

“Polysaccharide functions in seeds”
- Helen North (Institut Jean-Pierre Bourgin – Versailles, France)

“Cell wall: growth and development”
José Feijó (University of Maryland)
- Kalina Haas (Institut Jean-Pierre Bourgin – Versailles, France)
- Grégory Mouille (Institut Jean-Pierre Bourgin – Versailles, France)
- Sébastjen Schoenaers (Institut Jean-Pierre Bourgin – Versailles, France)

Common program with ZELCOR
“Plant biomass: agronomic reality and value chains” 
Wout Boerjan (VIB - Gent, Belgium)
- Paolo Corvo (Clariant)
"Integrated flexible processing chain for lignin valorization into carbon-based materials"
- Enrico Cozzoni (Grado Zero)

         > Practical sessions (16 hours)

Participants will choose one of the 4 following topics:

1. Biomass & degradability (coordinated by Matthieu Reymond)
Variation in biomass composition and stem histology – Case study in maize
- Analytical techniques for lignocellulose characterization (NMR, HPSEC, thioacidolysis, FTIR) (common with ZELCOR)
- NIRs, data analysis (Yves Griveau, Matthieu Reymond)
- Stem sections, staining and image analysis / quantification (Matthieu Reymond)

2. Cell wall synthesis and control of cell expansion (coordinated by Herman Höfte and Alexis Peaucelle)
Effect of chemical inhibitors on cellulose synthesis, cell wall properties and growth.
- Immuno-histochemistry of cell walls using triple labelling (Alexis Peaucelle)
- Real-time observation of cellulose synthase dynamics (spinning disc) (Alexis Peaucelle)
- Nanoscale measurement of cell wall mechanics (AFM) (Alexis Peaucelle / Kalina Haas)

3. Composition, architecture and specialized functions of cell wall polysaccharides in seeds (coordinated by Helen North)
In situ and biochemical analysis of the composition and structure of cell wall – Case study with Brassicaceae seeds
- Histological analysis of seed mucilage (staining, confocal and polarized microscopy) (Helen North / Adeline Berger)
- Biochemical analysis of polysaccharides (ionic chromatography, colorimetry, FTIR microscopy and data analysis) (Grégory Mouille / Salem Chabout)

4. Plant-fungi interactions (coordinated by Aline Voxeur)
Cell wall modifications induced during the interactions between necrotrophic fungus Botrytis cinerea and Arabidopsis
- Microscopic observation of infection and ROS staining (Cyril Gaertner / Aline Voxeur)
- Oligogalacturonide- (OG) and fungus-induced ROS production in Arabidopsis leaves (Luminol assay) (Martine Gonneau)
- Oligogalacturonomics (UHPLC-HRMSMS) (Aline Voxeur)

         > Presentations of the participants’ projects

         > Visits of SPS labs

         > Cultural excursion at the Versailles Castle


Via Saclay Plant Sciences
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A serine/threonine protein kinase encoding gene KERNEL NUMBER PER ROW6 regulates maize grain yield

A serine/threonine protein kinase encoding gene KERNEL NUMBER PER ROW6 regulates maize grain yield | Plant and Seed Biology | Scoop.it
Increasing grain yield of maize (Zea mays L.) is required to meet the rapidly expanding demands for maize-derived food, feed, and fuel. Breeders have enhanced grain productivity of maize hybrids by pyramiding desirable characteristics for larger ears. However, loci selected for improving grain productivity remain largely unclear. Here, we show that a serine/threonine protein kinase encoding gene KERNEL NUMBER PER ROW6 (KNR6) determines pistillate floret number and ear length. Overexpression of KNR6 or introgression of alleles lacking the insertions of two transposable elements in the regulatory region of KNR6 can significantly enhance grain yield. Further in vitro evidences indicate that KNR6 can interact with an Arf GTPase-activating protein (AGAP) and its phosphorylation by KNR6 may affect ear length and kernel number. This finding provides knowledge basis to enhance maize hybrids grain yield. Selection of kernel number per ear has improved maize yield, but the genetic base is unclear. Here, the authors reveal that a serine/threonine protein kinase KNR6 is a positive regulator of the trait and show in vitro evidences that KNR6 may function through phosphorylating an Arf GTPase-activating protein.
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Glandular trichomes: micro‐organs with model status? - Schuurink - 2020 - New Phytologist - Wiley Online Library

Glandular trichomes: micro‐organs with model status? - Schuurink - 2020 - New Phytologist - Wiley Online Library | Plant and Seed Biology | Scoop.it

Glandular trichomes are epidermal outgrowths that are the site of biosynthesis and storage of large quantities of specialized metabolites. Besides their role in the protection of plants against biotic and abiotic stresses, they have attracted interest owing to the importance of the compounds they produce for human use; for example, as pharmaceuticals, flavor and fragrance ingredients, or pesticides. Here, we review what novel concepts investigations on glandular trichomes have brought to the field of specialized metabolism, particularly with respect to chemical and enzymatic diversity. Furthermore, the next challenges in the field are understanding the metabolic network underlying the high productivity of glandular trichomes and the transport and storage of metabolites. Another emerging area is the development of glandular trichomes. Studies in some model species, essentially tomato, tobacco, and Artemisia, are now providing the first molecular clues, but many open questions remain: How is the distribution and density of different trichome types on the leaf surface controlled? When is the decision for an epidermal cell to differentiate into one type of trichome or another taken? Recent advances in gene editing make it now possible to address these questions and promise exciting discoveries in the near future.

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Les secrets de la longévité des graines | Académie d'Agriculture de France, séance du 18 mars, 14:00

Les secrets de la longévité des graines | Académie d'Agriculture de France, séance du 18 mars, 14:00 | Plant and Seed Biology | Scoop.it

Attention : la séance débutera exceptionnellement à 14h15 !

En agriculture, les semences incluent les graines et par extension d’autres organes de reproduction (bulbes, tubercules…), choisis pour être semés. Il existe deux grandes catégories de graines. D’une part, les graines dites orthodoxes qui supportent la dessiccation et conservent leur pouvoir germinatif pour de longues périodes (dormance) et peuvent par conséquent être entreposées sèches jusqu’à leur utilisation. Il existe d’autre part des graines dites récalcitrantes qui ne supportent pas une conservation au sec (e.g. graine du cacaoyer). Cette séance traitera uniquement des graines orthodoxes en rapport avec leur longévité à l’état sec.
La graine constitue le principal vecteur de multiplication chez les végétaux et, à ce titre, joue un rôle crucial, au niveau global, dans l’alimentation humaine et animale, notamment grâce à un stockage très élaboré de nombreuses macromolécules (protéines, amidon, lipides, …) et métabolites (e.g. vitamines, acides aminés essentiels que l’homme ne sait synthétiser). Elle correspond à un stade de développement critique qui présente de nombreuses spécificités, notamment en comparaison du développement de l’embryon humain. La longévité des graines est une problématique centrale aussi bien pour la conservation de la biodiversité que pour le succès des cultures végétales. La graine orthodoxe possède une grande diversité de systèmes (protection, détoxication, réparation) lui permettant de se conserver à l'état sec et de maintenir sa capacité germinative. La graine est ainsi un modèle de choix pour étudier la longévité et le vieillissement. En particulier, des longévités remarquables ont été signalées, par exemple pour le lotus sacré (Nelumbo nucifera) (près de 1 300 ans) et pour le palmier dattier (Phoenix dactylifera) (> 2 000 ans).
La réduction de la longévité des graines orthodoxes est souvent associée à l'oxydation de macromolécules cellulaires (acides nucléiques, protéines, lipides) (exposé de Christophe Bailly). Les graines orthodoxes possèdent deux stratégies principales pour lutter contre ces conditions stressantes : la protection et la réparation. Le mécanisme de protection inclut la formation d’un cytoplasme vitreux pour réduire les activités métaboliques cellulaires et la production d'antioxydants qui empêchent l'accumulation de macromolécules oxydées pendant le stockage des graines (exposé d’Olivier Leprince). Le système de réparation élimine les dommages accumulés durant le stockage. En particulier les graines de lotus sacré referment la plus grande quantité connue chez les êtres vivants d’une enzyme impliquée dans la réparation du protéome, nommée Protéine L-Isoaspartyl Méthyltansférase. Chez l’homme cette enzyme est connue pour avoir des propriété antiapoptotiques et serait impliquée dans plusieurs maladies neurodégénératives. Il y a donc une étonnante conservation des mécanismes impliqués dans la lutte contre le vieillissement cellulaire chez tous les organismes. Pendant le stockage à sec, la viabilité des graines diminue progressivement en raison de processus de vieillissement et / ou de détérioration. Les premiers symptômes sont un retard de germination des graines et un mauvais établissement des plantules, ce qui entraîne une réduction du rendement des cultures (exposé de Loïc Rajjou). Les mécanismes moléculaires impliqués dans la longévité des graines commencent à être bien connus (exposé de Julia Buitink). Le but de cette séance est de faire le point sur nos connaissances des mécanismes physiologiques, biochimiques et moléculaires régissant la longévité et le vieillissement des graines

Introduction
 
Introduction
Contrôle métabolique de la longévité des graines
Loïc RAJJOU , Biologiste végétal, spécialiste de la biologie des graines, professeur à AgroParisTech
 
Graines, vieillissement et dormances
Christophe BAILLY , Biologiste végétal, spécialiste de la biologie des graines, professeur à l'Université Pierre et Marie Curie (Paris)
 
État vitreux des graines et survie à l’état sec
Olivier LEPRINCE, Biologiste végétal, spécialiste en anhydrobiose pour la conservation des graines à l’état sec, professeur de physiologie végétale à Agrocampus Ouest
 
Mécanismes moléculaires de la survie à l’état sec des graines
Julia BUITINK, Biologiste végétal, spécialiste en biologie des graines, avec un intérêt particulier pour les approches de biologie des systèmes pour comprendre la survie des graines à l'état sec, directrice de recherche à l’INRA (Angers)
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Molecular and environmental factors regulating seed longevity 

Molecular and environmental factors regulating seed longevity  | Plant and Seed Biology | Scoop.it

Seed longevity is a central pivot of the preservation of biodiversity, being of main importance to face the challenges linked to global climate change and population growth. This complex, quantitative seed quality trait is acquired on the mother plant during the second part of seed development. Understanding what factors contribute to lifespan is one of the oldest and most challenging questions in plant biology. One of these challenges is to recognize that longevity depends on the storage conditions that are experimentally used because they determine the type and rate of deleterious conditions that lead to cell death and loss of viability. In this review, we will briefly review the different storage methods that accelerate the deteriorative reactions during storage and argue that a minimum amount of information is necessary to interpret the longevity data. Next, we will give an update on recent discoveries on the hormonal factors regulating longevity, both from the ABA signaling pathway but also other hormonal pathways. In addition, we will review the effect of both maternal and abiotic factors that influence longevity. In the last section of this review, we discuss the problems in unraveling cause-effect relationship between the time of death during storage and deteriorative reactions leading to seed ageing. We focus on the three major types of cellular damage, namely membrane permeability, lipid peroxidation and RNA integrity for which germination data on seed stored in dedicated seed banks for long period times are now available.

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Two distinct phases of chloroplast biogenesis during de-etiolation of Arabidopsis thaliana - Emilie Demarsy SPS-online seminar (video)

Two distinct phases of chloroplast biogenesis during de-etiolation of Arabidopsis thaliana - Emilie Demarsy SPS-online seminar (video) | Plant and Seed Biology | Scoop.it

Emilie Demarsy
(Plant physiology laboratory, University of Neuchâtel and Department of Botany and Plant Biology, University of Geneva, Switzerland)

 

Light triggers chloroplast differentiation in dark grown (etiolated) seedlings. A precursor organelle, the etioplast, transforms into a photosynthesizing chloroplast. Over the course of just a few hours, an extensive photosynthetic membrane system, the thylakoid, emerges. This requires synthesis of highly abundant membrane lipids as well as specific photosynthesis-associated proteins. But the sequence of events during chloroplast differentiation is still unclear. Using Serial Block Face Scanning Microscopy (SBF-SEM) we generated a time course of 3D reconstructions of entire cells and chloroplasts during differentiation, revealing number, volume as well as envelope and thylakoid membrane surface. The (ultra)structural data are completed with quantitative lipid and whole proteome data that together provide a time-resolved, multi-dimensional analysis of chloroplast biogenesis. Our data reveal the differential regulation of galactolipid synthesis pathways and sequential activation of photosystems. The superimposition of the structural and biochemical data reveals two distinct phases; an initial “Structure Establishment Phase” enabling onset of photosynthesis, followed by a “Chloroplast Proliferation Phase” coinciding with cell expansion. Thereby we establish a roadmap to chloroplast biogenesis, a critical process towards photoautotrophic growth and survival of young plants.

 

Authors of the study:

Rosa Pipitone1, Simona Eicke2, Barbara Pfister2, Gaetan Glauser3, Denis Falconet4, Thibaut Pralon1, Sam Zeeman2, Felix Kessler1, Emilie Demarsy1,5

1 Plant physiology laboratory, University of Neuchâtel, Neuchâtel, Switzerland
2 Institute of Agricultural Sciences, Department of Biology ETH Zurich, Zurich, Switzerland
3 Neuchâtel Platform of Analytical Chemistry, University of Neuchâtel, Neuchâtel, Switzerland
4 Laboratoire de Physiologie Cellulaire et Végétale, Institut National de Recherche Agronomique, Commissariat à l'Energie Atomique et aux Energies Alternatives, Grenoble, France
5 Department of Botany and Plant Biology, University of Geneva, CH-1211 Geneva 4, Switzerland




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A DMP -triggered in vivo maternal haploid induction system in the dicotyledonous Arabidopsis

A DMP -triggered in vivo maternal haploid induction system in the dicotyledonous Arabidopsis | Plant and Seed Biology | Scoop.it
Doubled haploid technology using inducer lines carrying mutations in ZmPLA1/MTL/NLD and ZmDMP1–4 has revolutionized traditional maize breeding. ZmPLA1/MTL/NLD is conserved in monocots and has been used to extend the system from maize to other monocots5–7, but no functional orthologue has been identified in dicots, while ZmDMP-like genes exist in both monocots and dicots4,8,9. Here, we report that loss-of-function mutations in the Arabidopsis thaliana ZmDMP-like genes AtDMP8 and AtDMP9 induce maternal haploids, with an average haploid induction rate of 2.1 ± 1.1%. In addition, to facilitate haploid seed identification in dicots, we established an efficient FAST-Red fluorescent marker-based haploid identification system that enables the identification of haploid seeds with >90% accuracy. These results show that mutations in DMP genes also trigger haploid induction in dicots. The conserved expression patterns and amino acid sequences of ZmDMP-like genes in dicots suggest that DMP mutations could be used to develop in vivo haploid induction systems in dicots. Mutations in the ZmDMP gene induce maternal haploids and facilitate breeding in maize. Now, a study extends this system of maize to dicots, showing that loss-of-function mutations in the Arabidopsis ZmDMP-like genes also induce maternal haploids.
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Plant 22-nt siRNAs mediate translational repression and stress adaptation

Plant 22-nt siRNAs mediate translational repression and stress adaptation | Plant and Seed Biology | Scoop.it
Small interfering RNAs (siRNAs) are essential for proper development and immunity in eukaryotes1. Plants produce siRNAs with lengths of 21, 22 or 24 nucleotides. The 21- and 24-nucleotide species mediate cleavage of messenger RNAs and DNA methylation2,3, respectively, but the biological functions of the 22-nucleotide siRNAs remain unknown. Here we report the identification and characterization of a group of endogenous 22-nucleotide siRNAs that are generated by the DICER-LIKE 2 (DCL2) protein in plants. When cytoplasmic RNA decay and DCL4 are deficient, the resulting massive accumulation of 22-nucleotide siRNAs causes pleiotropic growth disorders, including severe dwarfism, meristem defects and pigmentation. Notably, two genes that encode nitrate reductases—NIA1 and NIA2—produce nearly half of the 22-nucleotide siRNAs. Production of 22-nucleotide siRNAs triggers the amplification of gene silencing and induces translational repression both gene specifically and globally. Moreover, these 22-nucleotide siRNAs preferentially accumulate upon environmental stress, especially those siRNAs derived from NIA1/2, which act to restrain translation, inhibit plant growth and enhance stress responses. Thus, our research uncovers the unique properties of 22-nucleotide siRNAs, and reveals their importance in plant adaptation to environmental stresses. Characterization of 22-nucleotide short interfering RNAs in plants finds that they accumulate in response to environmental stress, causing translational repression, inhibition of plant growth and enhanced stress responses.
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Role for plant science in underpinning the objective of global nutritional security? 

Role for plant science in underpinning the objective of global nutritional security?  | Plant and Seed Biology | Scoop.it
Background

The challenges of achieving global food security have become more demanding as scientists have realized that not only calorie content but also food composition and colonic microbial content impact our health and well-being, dramatically. The ways that the nutrients we consume affect our health are highly complex due to the diversity of what we eat, the varying digestibility of what we eat, the changing composition and functioning of each individual’s gut microbiota, the differences in absorption and bioavailability of the nutrients we eat, the differences in responses between individuals to what they eat and the multi-fold mechanisms of action that nutrients have on our health.

 
Perspective and Conclusions

It has been accepted for more than 50 years that diets rich in plants, particularly fruit and vegetables, protect health, and yet such diets have declined, with lower fruit and vegetable content and much more cheap, sugary, oily, processed foods, over the same period. These dietary shifts have had a marked impact on the incidence of chronic diseases: obesity, metabolic diseases, type 2 diabetes and cardiovascular diseases. Greater support for research into the ways that plant-based foods impact health will be essential for changing dietary patterns to protect health and to achieve global nutritional security.

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The style and substance of plant flavonoid decoration; towards defining both structure and function

The style and substance of plant flavonoid decoration; towards defining both structure and function | Plant and Seed Biology | Scoop.it

Highlights

The review summarized the major decorative modifications of flavonoids in plants.

Hydroxylation, glycosylation, methylation and acylation of plant flavonoids has been discussed.

The knowledge accrued concerning the biological function of flavonoids has been summarized.

Over 8000 different flavonoids have been described and a considerable number of new flavonoid structures are being elucidated every year. The advent of metabolomics alongside the development of phytochemical genetics – wherein the genetic basis underlying the regulation of the levels of plant metabolites is determined – has provided a massive boost to such efforts. That said our understanding of the individual function(s) of the vast majority of the metabolites that constitute this important class of phytochemicals remains unknown. Here we review what is known concerning the major decorative modifications of flavonoids in plants, namely hydroxylation, glycosylation, methylation and acylation. Our major focus is with regard to the in planta function of these modified compounds, however, we also highlight the demonstrated bioactive roles which they possess. We additionally performed a comprehensive survey of the flavonoids listed in the KNApSAcK database in order to assess the frequency of occurrence of each type of flavonoid modification. We conclude that whilst considerable research has been carried out regarding the biological roles of flavonoids most studies to date have merely provided information on the compound class or sub-classes thereof as a whole with too little currently known on the specific role of individual metabolites. We, therefore, finally suggest a framework based on currently available tools by which the relative importance of the individual compounds can be assessed under various biological conditions in order to fill this knowledge-gap.

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AtMYB92 enhances fatty acid synthesis and suberin deposition in leaves of Nicotiana benthamiana (IJPB, SPS)

AtMYB92 enhances fatty acid synthesis and suberin deposition in leaves of Nicotiana benthamiana (IJPB, SPS) | Plant and Seed Biology | Scoop.it

Acyl lipids are important constituents of the plant cell. Depending on the cell type, requirements in acyl lipids vary greatly, implying a tight regulation of fatty acid and lipid metabolism. The discovery of the WRINKLED transcription factors, members of the AP2/EREBP family, has emphasized the importance of transcriptional regulations for adapting the rate of acyl chain production to cell requirements. Here we describe the identification of another activator of the fatty acid biosynthetic pathway, the Arabidopsis MYB92 transcription factor. This MYB, like all the members of the subgroups S10 and S24 of MYB transcription factors, can directly activate the promoter of BCCP2 that encodes a component of the fatty acid biosynthetic pathway. Two adjacent MYB cis‐regulatory elements are essential for the binding and activation of the BCCP2 promoter by MYB92. Overexpression of MYB92 or WRI1 in Nicotiana benthamiana induces the expression of fatty acid biosynthetic genes but results in the accumulation of different types of acyl lipids. In the presence of WRI1, triacylglycerol biosynthetic enzymes coded by constitutively expressed genes efficiently channel the excess fatty acids toward reserve lipid accumulation. In contrast, MYB92 activates both fatty acid and suberin biosynthetic genes; hence the remarkable increase in suberin monomers measured in leaves expressing MYB92. These results provide additional insight into the molecular mechanisms that control the biosynthesis of an important cell wall‐associated acylglycerol polymer playing critical roles in plants.


Via Saclay Plant Sciences
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"Do us a favor" a letter to D. Trump by H. Holden Thorp Editor-in-Chief, Science journals.

"Do us a favor" a letter to D. Trump by H. Holden Thorp Editor-in-Chief, Science journals. | Plant and Seed Biology | Scoop.it

 

 

“Do me a favor, speed it up, speed it up.” This is what U.S. President Donald Trump told the National Association of Counties Legislative Conference, recounting what he said to pharmaceutical executives about the progress toward a vac- cine for severe acute respiratory syndrome–coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 (COVID-19). Anthony Fauci, the long-time leader of the Na- tional Institute of Allergy and Infectious Diseases, has been telling the president repeatedly that developing the vaccine will take at least a year and a half—the same message con- veyed by pharmaceutical executives. Apparently, Trump thought that simply repeating his request would change the outcome. China has rightfully taken criticism for squelching attempts by scientists to report information during the out- break. Now, the United States government is doing similar things. Informing Fauci and other government scientists that they must clear all public comments with Vice President Mike Pence is unacceptable. This is not a time for someone who denies evolution, climate change, and the dangers of smoking to shape the public message. Thank goodness Fauci, Francis Collins [director of the U.S. National Institutes of Health (NIH)], and their colleagues across federal agencies are will- ing to soldier on and are gradually getting the message out.

 

While scientists are trying to share facts about the epi-demic, the administration either blocks those facts or restates them with contradictions. Transmission rates and death rates are not measurements that can be changed with will and an extroverted presentation. The administration has repeatedly said—as it did last week—that virus spread in the United States is contained, when it is clear from genomic evidence that community spread is occurring in Washington state and beyond. That kind of distortion and denial is dangerous and almost certainly contributed to the federal government’s sluggish response. After 3 years of debating whether the words of this administration matter, the words are now clearly a matter of life and death.

And although the steps required to produce a vaccine could possibly be made more efficient, many of them depend on biological and chemical processes that are essential. So the president might just as well have said, “Do me a favor, hurry up that warp drive.”

 

I don’t expect politicians to know Maxwell’s equations for electromagnetism or the Diels-Alder chemical reaction (alt- hough I can dream). But you can’t insult science when you don’t like it and then suddenly insist on something that science can’t give on demand. For the past 4 years, President Trump’s budgets have made deep cuts to science, including cuts to funding for the Centers for Disease Control and Pre- vention and the NIH. With this administration’s disregard for science of the Environmental Protection Agency and the Na- tional Oceanic and Atmospheric Administration, and the stalled naming of a director for the Office of Science and Technology Policy—all to support political goals—the nation has had nearly 4 years of harming and ignoring science.

Now, the president suddenly needs science. But the cen- turies spent elucidating fundamental principles that govern the natural world—evolution, gravity, quantum mechanics— involved laying the groundwork for knowing what we can and cannot do. The ways that scientists accumulate and ana- lyze evidence, apply inductive reasoning, and subject findings to scrutiny by peers have been proven over the years to give rise to robust knowledge. These processes are being applied to the COVID-19 crisis through international collaboration at breakneck, unprecedented speed; Science published two new papers earlier this month on SARS-CoV-2, and more are on the way. But the same concepts that are used to describe na- ture are used to create new tools. So, asking for a vaccine and distorting the science at the same time are shockingly disso- nant.

 

A vaccine has to have a fundamental scientific basis. It has to be manufacturable. It has to be safe. This could take a year and a half—or much longer. Pharmaceutical executives have every incentive to get there quickly— they will be selling the vaccine after all—but thankfully they also know that you can’t break the laws of nature to get there.

 

Maybe we should be happy. Three years ago, the president declared his skepticism of vaccines and tried to launch an an- tivaccine task force. Now he suddenly loves vaccines.

But do us a favor, Mr. President. If you want something, start treating science and its principles with respect.

 

Published online 11 March 2020 10.1126/science.abb6502

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Santé des plantes : ressources naturelles et biologie contemporaine, Colloque scientifique • 15 mai 2020 • SNHF, PARIS

Santé des plantes : ressources naturelles et biologie contemporaine, Colloque scientifique • 15 mai 2020 • SNHF, PARIS | Plant and Seed Biology | Scoop.it

SANTÉ DES PLANTES : RESSOURCES NATURELLES ET BIOLOGIE CONTEMPORAINE

Colloque scientifique • 15 mai 2020 • SNHF, PARIS
L’ONU (Organisation des Nations Unies pour l’alimentation et l’agriculture) a proclamé 2020 l’Année internationale de la santé des végétaux (International Year of Plant Health, IYPH). Cette année est une occasion unique de sensibiliser le monde entier à la manière dont la protection phytosanitaire des cultures peut contribuer à éliminer la faim, à réduire la pauvreté, à protéger l’environnement et à impulser le développement économique.
C’est dans ce cadre que la SNHF a choisi comme thème de son colloque annuel: «Santé des plantes : ressources naturelles et biologie contemporaine».


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Regulation of ovule initiation by gibberellins and brassinosteroids in tomato and Arabidopsis: two plant species, two molecular mechanisms 

Regulation of ovule initiation by gibberellins and brassinosteroids in tomato and Arabidopsis: two plant species, two molecular mechanisms  | Plant and Seed Biology | Scoop.it

Ovule primordia formation is a complex developmental process with a strong impact on the production of seeds. In Arabidopsis this process is controlled by a gene network, including components of the signalling pathways of auxin, brassinosteroids (BRs) and cytokinins. Recently, we have shown that gibberellins (GAs) also play an important role in ovule primordia initiation, inhibiting ovule formation in both Arabidopsis and tomato. Here we reveal that BRs also participate in the control of ovule initiation in tomato, by promoting an increase on ovule primordia formation. Moreover, molecular and genetic analyses of the co‐regulation by GAs and BRs of the control of ovule initiation indicate that two different mechanisms occur in tomato and Arabidopsis. In tomato, GAs act downstream of BRs. BRs regulate ovule number through the downregulation of GA biosynthesis, which provokes stabilization of DELLA proteins that will finally promote ovule primordia initiation. In contrast, in Arabidopsis both GAs and BRs regulate ovule number independently of the activity levels of the other hormone. Taken together, our data strongly suggest that different molecular mechanisms could operate in different plant species to regulate identical developmental processes even, as for ovule primordia initiation, if the same set of hormones trigger similar responses, adding a new level of complexity.

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UPSaclay - Programme de bourses internationales de master

UPSaclay - Programme de bourses internationales de master | Plant and Seed Biology | Scoop.it

L’Université Paris-Saclay reconduit son programme de bourses internationales de master pour l’année académique 2020/2021.

La présentation de ce programme est en ligne sur le site internet de l’Université Paris-Saclay.

 

Voir informations en FR et EN.


Via Life Sciences UPSaclay, Saclay Plant Sciences
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Gynoecium size and ovule number are interconnected traits that impact seed yield 

Gynoecium size and ovule number are interconnected traits that impact seed yield  | Plant and Seed Biology | Scoop.it

Authors: Mara Cucinotta, Maurizio Di Marzo, Andrea Guazzotti, Stefan de Folter, Martin M. Kater and Lucia Colombo.

 

Journal of Experimental Botany (2020)

 

Abstract: "Angiosperms form the largest group of land plants and display an astonishing diversity of floral structures. The development of flowers greatly contributed to the evolutionary success of the angiosperms as they guarantee efficient reproduction with the help of either biotic or abiotic vectors. The female reproductive part of the flower is the gynoecium (also called pistil). Ovules arise from meristematic tissue within the gynoecium. Upon fertilization, these ovules develop into seeds while the gynoecium turns into a fruit. Gene regulatory networks involving transcription factors and hormonal communication regulate ovule primordium initiation, spacing on the placenta, and development. Ovule number and gynoecium size are usually correlated and several genetic factors that impact these traits have been identified. Understanding and fine-tuning the gene regulatory networks influencing ovule number and pistil length open up strategies for crop yield improvement, which is pivotal in light of a rapidly growing world population. In this review, we present an overview of the current knowledge of the genes and hormones involved in determining ovule number and gynoecium size. We propose a model for the gene regulatory network that guides the developmental processes that determine seed yield."

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Special Current Opinion in Biotechnology Issue: Plant Biotechnology

Special Current Opinion in Biotechnology Issue: Plant Biotechnology | Plant and Seed Biology | Scoop.it

Since most of us will have a few days off this coming week as we welcome in 2020, I’d like to highlight some of the engrossing reviews in this special issue of Current Opinion in Biotechnology, edited by Ralf Reski, Gary Foster & Ed Rybicki.  Several of the articles focus on Molecular Pharming, or the production of high-value medicinal products in plants. Such efforts vaulted into the headlines with the use of ZMapp (a cocktail of plant-made monoclonal antibodies) during the 2014–2016 Ebola virus outbreak in West Africa. Some of the reviews in this Special Issue focus on products (Molecular farming for therapies and vaccines in Africa; Cancer biologics made in plants), others on strategies for increasing the efficiency or versatility of plants as pharmaceutical producers (Proteases of Nicotiana benthamiana: an emerging battle for molecular farming; Optimizing product quality in molecular farming; Innovation in plant-based transient protein expression for infectious disease prevention and preparedness), and others on the value or optimization of specific types of plants (Green algal hydrocarbon metabolism is an exceptional source of sustainable chemicals; Mosses in biotechnology). There are also useful reviews of progress and policies concerning gene-edited plants. (Summary by Mary Williams) Curr. Opin. Biotech. Feb. 2020.

 

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