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Mimicking natural polymorphism in eIF4E by CRISPR-Cas9 base editing is associated with resistance to potyviruses.
No full textIn many crop species, natural variation in eIF4E proteins confers resistance to potyviruses. Gene editing offers new opportunities to transfer genetic resistance to crops that seem to lack natural eIF4E alleles. However, because eIF4E are physiologically important proteins, any introduced modification for virus resistance must not bring adverse phenotype effects. In this study, we assessed the role of amino acid substitutions encoded by a Pisum sativum eIF4E virus-resistance allele (W69L, T80D S81D, S84A, G114R and N176K) by introducing them independently into the Arabidopsis thaliana eIF4E1 gene, a susceptibility factor to the Clover yellow vein virus (ClYVV). Results show that most mutations were sufficient to prevent ClYVV accumulation in plants without affecting plant growth. In addition, two of these engineered resistance alleles can be combined with a loss-of-function eIFiso4E to expand the resistance spectrum to other potyviruses. Finally, we use CRISPR-nCas9-cytidine deaminase technology to convert the Arabidopsis eIF4E1 susceptibility allele into a resistance allele by introducing the N176K mutation with a single-point mutation through C-to-G base editing to generate resistant plants. This study shows how combining knowledge on pathogen susceptibility factors with precise genome-editing technologies offers a feasible solution for engineering transgene-free genetic resistance in plants, even across species barriers
Les arrangements pour l’accès au foncier agricole périurbain
No full textL’article étudie les interactions entre logiques agricoles et modalités d’accès à la terre en contexte périurbain. S’ancrant dans la géographie critique du droit, il présente les résultats d’une enquête menée auprès de 17 exploitations périurbaines de Montpellier. Plus d’un tiers des surfaces enquêtées est exploité selon le mode d’arrangements informels. Ceux-ci échappent au statut du fermage et concernent notamment les filières blé-melon, chevaux de loisirs et fourrage et parcours. Les espaces liés à ces arrangements sont issus du retrait de la vigne, de l’anticipation de l’urbanisation, mais aussi du retrait plus ancien de l’élevage pastoral dans les garrigues. Ils illustrent la production locale d’une norme sociale contournant la règle du fermage. En donnant la possibilité aux propriétaires, souvent viticulteurs et dominant le système foncier local, de garder le contrôle sur leurs terres cultivées par d’autres, ils conduisent à l’exclusion des agriculteurs non intégrés socialement dans chaque commune, notamment les porteurs de projet agricole venus d’ailleurs.The article deals with the farmland access issue on urban fringes. Taking a legal geography approach, it presents the results of a survey of 17 farms near Montpellier. More than a third of the surveyed areas are exploited by informal arrangements. The tenant farming who protects a lot the farmer does not cover these contracts. These informal contracts develop in particular the wheat/melon, leisure horses and rangeland sectors. The spaces linked to these arrangements come from the wine crisis, from the anticipation of urbanization, but also from the older crisis of pastoral sector. Arrangements illustrate the local production of a social norm bypassing the tenant farming rule. Winemakers are often landowners. They dominate the local land tenure system. Arrangements, giving them the power to control their cultivated lands by others and lead to the exclusion of non-socially integrated farmers
Productivity analysis and non-linear gain scheduling approach for multi-species bioprocesses with product inhibition
No full textBioprocesses with product inhibition are known to allow species coexistence. In this work, we first study the productivity of the different possible equilibria, depending on the operating conditions, and show that single species offers the best performances. Then, we propose a control strategy to stabilize the dynamics about the desired equilibria, in presence of instability. Based on output feedback linearization, we propose a family of controllers and a gain-scheduling approach to adapt the controller. Finally, we illustrate our approach on numerical simulations, showing that the attraction basin of the closed-loop system is improved by considering the gain-scheduling approach
Le chêne faginé (Quercus faginea, Fagaceae) en Algérie : potentiel germinatif et variabilité morphologique des glands et des semis
No full textContexte et buts visés – Le chêne faginé, Quercus faginea Lam. (Fagaceae), représente un intérêt patrimonial, écologique et taxonomique remarquable en Algérie, mais malheureusement l’espèce est menacée et peu étudiée. L’objectif de ce travail est d’étudier la variabilité morphologique et le potentiel germinatif des glands de Q. faginea en Algérie, d’examiner la variabilité de la croissance des semis et d’évaluer l’influence des traitements physiques sur le potentiel germinatif et le développement ultérieur des semis, tant au niveau intra- qu’inter-stationnel.
Méthodes – Des glands mûrs de chêne faginé récoltés sur quatre stations de l’espèce en Algérie ont été utilisés. Sur chaque station, dix arbres ont été sélectionnés, représentés par 100 glands chacun. Une analyse de traits phénotypiques a été réalisée sur les glands ; ensuite un ensemble de traitements physiques ont été effectués afin de tester leur effet sur la germination. Les semis issus de la germination ont été transplantés dans des sachets en polyéthylène et plusieurs caractères de croissance ont été mesurés.
Résultats-clés – L’étude comparative morphologique et germinative révèle des glands plus longs et plus lourds à la station de Baloul, et des feuilles plus petites et plus légères à la station de Chélia, en comparaison avec les autres stations. Un effet significatif des traitements sur la germination a été montré dans toutes les stations. La taille des glands n’a aucune influence sur le développement des jeunes semis.
Conclusions – Nos résultats montrent une variabilité morphologique inter-stationnelle des feuilles et des glands du chêne faginé. Cette diversité est probablement la conséquence de variations génétiques et/ou des conditions environnementales des stations. L’étude de la germination et de l’évolution de plants révèle un potentiel germinatif et de croissance considérables. Compte tenu de l’ensemble des facteurs qui menacent la pérennité du chêne faginé en Algérie, nous recommandons des actions pour la conservation de l’espèce telles que des reboisements, des plantations ex situ et des clôtures de protection pour éviter une régression réelle et irréversible des peuplements qui conduirait très probablement à sa disparition.Background and aims – The Portuguese Oak, Quercus faginea Lam. (Fagaceae) forms part of iconic Mediterranean forest communities and is of great ecological and taxonomic value in Algeria. Unfortunately, the species is under threat and its populations remain poorly characterized. The aim of this paper is to study the variability of acorn morphology and germination potential of Q. faginea in Algeria, to examine variability in the growth of seedlings and to evaluate the influence of physical treatments on germination capacity and the subsequent development of seedlings at the intra- and inter-provenance levels.
Methods – Mature acorns from four Q. faginea provenances of the species in Algeria were used for this work. In each provenance, ten trees were selected, and 100 acorns collected from each tree. Prior to germination, phenotypic seed traits were measured and a set of physical treatments was performed. The germinated seedlings were transplanted into polyethylene bags and several characteristics of plant growth were measured.
Key results – The comparative analysis on acorn morphology and germination features revealed heavier acorns in the Baloul provenance and smaller and lighter leaves in the Chelia provenance, in comparison with other provenances. Germination features and seedling growth showed that the size of the acorns had no influence on seedling development.
Conclusions – Our results show a morphological variability of leaves and acorns of the Portuguese Oak at the inter-provenance level. This diversity is probably a consequence of genetic variation and / or variable environmental conditions of the provenances. The study of the germination and seedling development reveals a considerable potential for germination and growth. Given all the factors that threaten the persistence of Portuguese Oak in Algeria, we recommend conservation action for the species through reforestation, ex situ plantations and protective fences to avoid genuine and irreversible population regression, which would most likely lead to its disappearance
Model balancing: consistent in-vivo kinetic constants and metabolic states obtained by convex optimisation
No full textEnzyme kinetic constants in vivo are largely unknown, which limits the construction of large metabolic
models. In theory, kinetic constants can be fitted to measured metabolic fluxes, metabolite concentrations,
and enzyme concentrations, but these estimation problems are typically non-convex. This makes them hard
to solve, especially if models are large. Here I assume that the metabolic fluxes are given and show that
consistent kinetic constants, metabolite levels, and enzyme levels can then be found by solving a convex
optimality problem. If logarithmic kinetic constants and metabolite concentrations are used as free variables
and if Gaussian priors are employed, the posterior density is strictly convex. The resulting estimation method,
called model balancing, can employ a wide range of rate laws, accounts for thermodynamic constraints on
parameters, and considers the dependences between flux directions and metabolite concentrations through
thermodynamic forces. It can be used to complete and adjust available data, to estimate in-vivo kinetic
constants from omics data, or to construct plausible metabolic states with a predefined flux distribution. To
demonstrate model balancing and to assess its practical use, I balance a model of E. coli central metabolism
with artificial or experimental data. The tests show what information about kinetic constants can be extracted
from omics data and reveal practical limits of estimating kinetic constants in vivo
Omeprazole Treatment Enhances Nitrogen Use Efficiency Through Increased Nitrogen Uptake and Assimilation in Corn.
No full textOmeprazole is a selective proton pump inhibitor in humans that inhibits the H+/K+-ATPase of gastric parietal cells. Omeprazole has been recently shown to act as a plant growth regulator and enhancer of salt stress tolerance. Here, we report that omeprazole treatment in hydroponically grown maize improves nitrogen uptake and assimilation. The presence of micromolar concentrations of omeprazole in the nutrient solution alleviates the chlorosis and growth inhibition induced by low nitrogen availability. Nitrate uptake and assimilation is enhanced in omeprazole treated plants through changes in nitrate reductase activity, primary metabolism, and gene expression. Omeprazole enhances nitrate assimilation through an interaction with nitrate reductase, altering its activation state and affinity for nitrate as a substrate. Omeprazole and its targets represent a novel method for enhancing nitrogen use efficiency in plant
Evolution et adaptation au changement climatique chez les sapins méditerranéens. Mise en place d’un site d’étude sur le Mont Ventoux
No full textUse of Machine Learning and Infrared Spectra for Rheological Characterization and Application to the Apricot
No full textFast advancement of machine learning methods and constant growth of the areas of application open up new horizons for large data management and processing. Among the various types of data available for analysis, the Fourier Transform InfraRed (FTIR) spectroscopy spectra are very challenging datasets to consider. In this study, machine learning is used to analyze and predict a rheological parameter: firmness. Various statistics have been gathered including both chemistry (such as ethylene, titrable acidity or sugars) and spectra values to visualize and analyze a dataset of 731 biological samples. Two-dimensional (2D) and three-dimensional (3D) principal component analyses (PCA) are used to evaluate their ability to discriminate for one parameter: firmness. Partial least squared regression (PLSR) modeling has been carried out to predict the rheological parameter using either sixteen physicochemical parameters or only the infrared spectra. We show that (i) the spectra alone allows good discrimination of the samples based on rheology, (ii) 3D-PCA allows comprehensive and informative
visualization of the data, and (iii) that the rheological parameters are predicted accurately using a regression method such as PLSR; instead of using chemical parameters which are laborious to obtain, Mid-FTIR spectra gathering all physicochemical information could be used for efficient prediction of firmness. As a conclusion, rheological and chemical parameters allow good discrimination of the samples according to their firmness. However, using only the IR spectra leads to better results. A good predictive model was built for the prediction of the firmness of the fruit, and we reached a coefficient of determination R2 value of 0.90. This method outperforms a model based on physicochemical descriptors only. Such an approach could be very helpful to technologists and farmers