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Genetic diversity in Morocco’ sunflower “Helianthus annuus L.” gene-bank for autumn-early winter plantation conditions: Agro-morpho-physiological screening
No full textInternational audienceDespite Morocco's reliance on sunflower as an oilseed crop, little is known about its agronomic performance when sown in autumn or early winter. This knowledge gap is critical, as spring-sown varieties have shown declining performance in recent years under intensifying climate stress. Therefore, targeted breeding strategies could discover genotypes suitable for autumn or early winter sowing, with cold tolerance as a key selection criterion. Currently, ‘Ichraq’ is the only autumn-planted sunflower variety officially registered in Morocco, although efforts to release additional tolerant varieties are underway. This study evaluated 31 genotypes (MGB1 to MGB31) selected from various environments under autumn planting conditions and conserved in the Moroccan Gene Bank. These genotypes were planted in early winter at a mountainous site known for its pronounced winter cold. Eighteen Morphological, physiological and agronomic parameters including initial vigor, leaf area, seed yield, oil content etc., were assessed using both univariate and multivariate statistical approaches. Analysis of variance revealed significant genotypic differences across most traits, indicating substantial genetic variation. Notably, seed oil content ranged from 23.28% (MGB26) to 43.88% (MGB5), and seed yield from 1400 kg/ha (MGB7) to 5400 kg/ha (MGB8). Principal component analysis (PCA) identified that the first principal component, accounting for over 24% of the total phenotypic variance, exhibits a strong positive loading of yield-related traits and chlorophyll content, while displaying a pronounced negative loading for oil content variables. This opposing gradient indicates a clear trade-off between vegetative productivity and oil accumulation across the evaluated genotypes. Hierarchical cluster analysis resolved the germplasm into two principal clusters with high within-group similarity, each further partitioned into relatively homogeneous subgroups. Notably, several genotypes outperformed the control variety Ichraq, underscoring their potential for autumn or early winter cultivation. Nonetheless, essential multi-environment trials remain to validate their phenotypic stability and to ascertain their value as genetic resources for sunflower breeding programs in Morocco and other Mediterranean agro-ecosystems
Contrasting genomic routes to domestication in Occidental and Oriental pears
No full textAbstract The domestication of perennial fruit trees remains poorly understood compared with annual crops, which were shaped by strong bottlenecks and elevated genetic load. Pears ( Pyrus spp.) provide an ideal model for exploring how long-lived, outcrossing crops evolved under human selection. Here, we combined high-coverage whole-genome resequencing of 396 wild and cultivated accessions from Occidental and Oriental pears with analyses of nucleotide and transposable element (TE) polymorphisms to reconstruct the demographic and adaptive history of pear domestication. Demographic inferences revealed weak or no domestication bottlenecks and extensive gene flow between wild and cultivated populations. In the Occidental lineage, dessert and perry P. communis cultivars underwent independent domestications from the same wild progenitor, P. pyraster , with divergent selection linked to fruit use. In the Oriental lineage, regionally independent domestications gave rise to Chinese and Japanese P. pyrifolia cultivars, shaped by both environmental adaptation and human selection. Selection scans identified lineage- and use-specific targets related to fruit texture, metabolism, and immunity. Contrary to the classical “cost of domestication” hypothesis, cultivated pears carried fewer deleterious variants than their wild relatives, suggesting efficient purging through selection and introgression. TE insertions mirrored population structure and occasionally occurred near selected genes, indicating a limited but detectable adaptive role. Together, our findings go beyond confirming the dual origins of Pyrus domestication to reveal contrasting demographic and adaptive pathways in Occidental and Oriental pears, illustrating independent adaptive trajectories in perennial crops, where long lifespan, self-incompatibility, and recurrent introgression shape distinctive genomic outcomes
A reference-free pipeline for detecting shared transposable elements from pan-genomes to retrace their dynamics in a species
No full textInternational audienceAbstract Background The role of transposable elements (TEs) in host adaptation has gained interest in recent years. Individuals of the same species undergo independent TE insertions, providing genetic variability within populations, upon which natural selection can act to foster adaptation to environmental conditions. Results As de novo assembled genomes are becoming increasingly affordable, helping to overcome the bias introduced by relying on a single reference genome, there is a growing need for suitable pangenomic tools to explore the genomic diversity within a species. We developed a new pipeline called panREPET that identifies TE insertions shared by groups of individuals. Unlike other pangenomic tools, panREPET operates independently of a reference genome and provides the precise sequence and genomic coordinates of each TE copy for each genome. Conclusions We showcase the potential of this tool by identifying TE insertions shared among 42 Brachypodium distachyo n genomes and by comparing our results with those of existing tools to demonstrate its advantages. Using panREPET, we were able to date two major TE bursts corresponding to major climate events: 22 kya during the Last Glacial Maximum and 10 kya during the Holocene, showing a potential link between environmental stress and TE activity
Intermediate-complexity parameterisation of blowing snow in the ICOLMDZ AGCM: development and first applications in Antarctica
No full textInternational audienceRecent regional model findings suggest that the aeolian erosion of surface snow is a significant contribution to the overall Antarctic surface mass balance (SMB) through ice crystals sublimation and export outside of the ice sheet. Such findings raise the question of the relevance of accounting for such a process also in global climate models. This study presents the development of an intermediate-complexity parameterisation of blowing snow for the ICOLMDZ atmospheric general circulation model, the atmospheric component of the IPSL Coupled Model. The parameterisation is designed to be a trade-off between physical complexity and applicability in a general circulation model, with constraints on numerical cost and stability. The parameterisation is evaluated with in situ observations using limited-area simulations over Adélie Land. The model exhibits satisfactory results in terms of summer wind speed, temperature and intensity of blowing snow fluxes. In winter, blowing snow intensity and occurrences are overestimated close to the coast, concurring with a positive wind speed bias. In terms of blowing snow occurrences throughout the year, ICOLMDZ exhibits comparable performance with the regional atmospheric model MAR. Boundary-layer moistening and cooling as well as changes in surface radiative fluxes due to blowing snow crystals are also quantified in the simulations. Global simulations at standard global climate model resolution are carried out to investigate how the Antarctic SMB is modified with the activation of the blowing snow parameterisation. Results show an overall decrease of the net snow accumulation in the escarpment region due to surface snow erosion and an increase along the coast due to blowing snow deposition and increase in precipitation
: @nimal Biological Resources for Integrated and Digital Genomics
No full textLa plateforme @BRIDGe propose une offre intégrée de services: de la conservation de l'échantillon biologique à son analyse au niveau tissulaire, cellulaire et moléculaire. Dédiée à la génomique des animaux domestiques, ses compétences et ses équipements lui permettent de participer à des projets concernant la biologie humaine ou des modèles biomédicaux. Elle est certifiée ISO 9001:2015 depuis 2018 pour toutes ses activités
A solution to the mystery of the sub-harmonic series via a linear model of the cochlea
No full textIn this paper, we study a simple linear model of the cochlea as a set of vibrating strings. We make hypothesis that the information sent to the auditory cortex is the energy stored in the strings and consider all oscillation modes of the strings. We show the emergence of the sub-harmonic series whose existence was hypothesized in the XVI century to explain the consonance of the minor chord. We additionally show how the nonlinearity of the energy can be used to study the emergence of the combination tone (Tartini’s third sound) shedding new light on this long debated subject
Towards Claiming a Detection of Gravitational Memory
No full textInternational audienceGravitational memory is a zero-frequency effect associated with a permanent change in the asymptotic spacetime metric induced by radiation. While its universal manifestation is a net change of proper distances, gravitational-wave detectors are intrinsically insensitive to the final offset and can only probe the associated transition. A central challenge for any claim of detection therefore lies in defining a physically meaningful and operationally robust model of this time-dependent signal, which is uniquely attributable to gravitational memory and distinguishable from purely oscillatory radiation. In this work, we propose a general solution to this challenge. Building on a self-contained review of the theory of gravitational memory, we discuss a theoretical framework for defining and modeling a gravitational memory rise, in particular applicable to compact binary coalescences. Specializing to space-based detectors, we analyze the response of LISA to gravitational radiation including a memory contribution, with particular emphasis on mergers of supermassive black hole binaries, which offer the most promising prospects for a first single-event detection. The framework developed here provides the theoretical foundation for statistically well-defined hypothesis testing between memory-free and memory-full radiation and quantitative assessments of detection prospects. As such, these results establish a principled pathway toward a future observational claim of gravitational memory
Resonance fluorescence and indistinguishable photons from a coherently driven B centre in hBN
No full textInternational audienceOptically active defects in hexagonal boron nitride (hBN) have become amongst the most attractive single-photon emitters in the solid state, owing to their high-quality photophysical properties, combined with the unlimited possibilities of integration offered by the host van der Waals material. In particular, the B centres, with their narrow linewidth, low wavelength spread and controllable positioning, have raised a particular interest for integrated quantum photonics. However, to date, either their excitation or their detection has been performed non-resonantly due to the difficulty of rejecting the backreflected laser light at the same wavelength, thereby preventing to take full benefit from their high coherence in quantum protocols. Here, we make use of narrow-linewidth emitters integrated in a hybrid metal-dielectric structure to implement cross-polarisation laser rejection. This allows us to observe resonantly scattered photons, with associated experimental signatures of optical coherence in both continuous-wave (cw) and pulsed regimes, respectively the Mollow triplet and Hong-Ou-Mandel interference from zero-phonon-line emission. The two-photon interference visibilities of 0.93 ± 0.21 and 0.92 ± 0.26 we measured for two emitters demonstrate the potential of B centres in hBN for applications to integrated quantum information
