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Engineering Synthetic Apomixis in Hybrid Rice
No full textEG, IK, RM, and VS are co-inventors of patent WO2024074888 (PCT/IB2023/000562).International audienceThe transfer of apomixis, a clonal mode of reproduction by seeds, to crops has the potential to revolutionize agriculture by enabling the generation of one-line F1 hybrids that propagate clonally by seeds from one generation to the next. However, despite nearly four decades of intensive research, all the attempts to transfer the identified genetic determinants of apomixis from naturally apomictic wild plants to their crop relatives have failed to produce apomictic crops. Engineering of apomixis, mimicking the key features of a natural form of apomixis known as gametophytic diplosporous apomixis, has recently been achieved in rice and further improvements by the introduction of a single “all-in-one” T-DNA construct into calli derived from F1 hybrid seed embryos resulted in high frequency of clonal seeds. The T-DNA encodes a constitutively expressed Cas9 protein guided by sgRNAs designed to knock-out the functions of three genes essential for regulating crucial steps involved in meiosis, thereby eliminating meiosis and creating the Mitosis instead of Meiosis (MiMe) triple mutant. Additionally, the T-DNA contains another gene expression cassette consisting of a parthenogenetic trigger, the BABY BOOM1 (BBM1) transcription factor driven by an egg cell-specific (ECS) promoter. Inactivation of the three MiMe genes converts meiosis into mitosis—apomeiosis—yielding unrecombined and unreduced male and female spores developing into gametophytes. The BBM1 expression triggers parthenogenetic development of an embryo from the diploid egg cell of the female gametophyte. The endosperm develops sexually by the fusion of a diploid sperm cell and the central cell of the female gametophyte, which contains two diploid polar nuclei, resulting in an initially hexaploid endosperm. To date, the “all-in-one” T-DNA method has proved to be the most efficient for achieving high frequency (95–100% clonal seeds) synthetic apomixis in rice. Since the original publication, we have successfully generated synthetic apomictic events in three additional F1 hybrids. Here, we describe the methods for designing T-DNA constructs, analyzing mutations in first-generation (T0) MiMe mutant plants of F1 hybrids, and ascertaining the apomictic nature of the progenies from confirmed MiMe F1 hybrids, which relies on the egg cell-specific accumulation of BBM1
Comment dépolluer les friches industrielles face à la défiance des habitants ?
No full textNational audiencePrès de huit Français sur dix vivent à proximité d’une friche polluée. Malgré les opérations de dépollution, les politiques de reconversion et l’objectif zéro artificialisation nette (ZAN), plusieurs milliers de sites restent à l’abandon. Entre incertitudes techniques, coûts de dépollution cachés et mémoire collective, la confiance des habitants reste difficile à restaurer
Indigenous Peoples and local communities report a consistent decline in the body mass of birds across three continents
No full textInternational audienceIncreasing evidence shows that genuine collaboration between scientists and Indigenous Peoples and local communities can deepen global understanding of species' ecological distribution ranges, baselines and trends. In this study, we explore trends in bird body mass as reflected in the collective biocultural memory of 10 place-based communities on three continents. To do so, we conducted a globally coordinated survey, asking 1,434 adult participants about the most common bird species around their territories both at present and during their childhood. The survey resulted in 6,914 unique bird reports, corresponding to 283 bird species and covering an 80-year period (1940-2020). By combining our ethno-ornithological dataset with scientific data on species' body mass, we assessed whether the composition of locally abundant bird assemblages has shifted towards smaller-bodied species over time. Our results show a general shift in the bird species observed over the participants' lifetimes, with recent species assemblages being composed of species with smaller body sizes than those in the past. Despite variation among sites, we find an overall statistically significant body mass reduction of 72% across all sites over 80 years. This work illustrates that the depth of the current avian extinction crisis, which has been well documented by scientists, is also widely acknowledged by Indigenous Peoples and local communities through their deep ecological knowledge and place-based observations. It highlights the substantial benefits of establishing meaningful collaborations across different knowledge systems to increase the evidence basis that underpins biodiversity policy and practice
Comparative analysis of PRR receptors and R genes reveals structural and functional divergence between wild, ancestral, and commercial citrus species
No full textInternational audienceBackground: Citriculture holds significant socioeconomic importance but is adversely affected by diseases that reduce productivity. Plant disease resistance is typically relies on efficient defense mechanisms - PTI and ETI - involving PRR receptors and R genes responsible for pathogen recognition and the initiation of defense responses. Results: In silico analyses performed on 11 genomes of 10 Citrus species, as well one genome of each Poncirus trifoliata and Fortunella hindsii, enabled the identification and classification of PRR receptors and R genes, analysis of gene duplication and clusters, validation of findings using RNA-seq libraries, and assessment of inter- and intraspecific variability across 43 additional accessions. Conclusions: Our results show that PRR receptors and genes are organized in clusters and exhibit both inter- and intraspecific diversity, with wild citrus species presenting lower gene counts compared to ancestral and hybrid species. Wild species showed a predominance of membrane-associated PRRs (RLKs and RLPs), potentially linked to early pathogen recognition, whereas ancestral and hybrid species exhibited higher abundance of intracellular receptors (CNL and TNL). These patterns suggest distinct immune strategies among citrus species, although further functional studies are required to confirm their roles in PTI or ETI responses
Sustainable treatment of banana leaves for phytosanitary applications: impact, spreading, and impregnation of mineral oil
No full textInternational audienceBACKGROUNDEfficient application of phytosanitary sprays is essential for sustainable control of foliar fungal diseases such as Black Sigatoka in banana crops. Mineral oils are commonly used for their fungistatic properties, yet their modes-of-action, particularly their interactions with leaf tissues, remain poorly understood. This study aims to elucidate the physical behavior of mineral oil droplets on banana leaves and their subsequent diffusion into internal tissues.RESULTSHigh-speed imaging shows that mineral oil droplets reach their maximum spread without retraction and exhibit only low splashing at high impact velocities. Spray coverage is strongly anisotropic and increases over time following a power-law scaling (ta with α = 0.21 ± 0.02), in agreement with Tanner's law. Micro-infrared spectroscopy reveals that mineral oil penetrates the leaf, with preferential accumulation in the palisade parenchyma. Diffusion into internal leaf tissues, specifically the palisade parenchyma, follows Fick's law after a latency of ≈3.6 h, with an effective diffusion coefficient of (1.2 ± 0.8) × 10−8 cm2 s−1.CONCLUSIONThis study provides the first direct evidence that mineral oils not only protect leaf surfaces, but also diffuse into internal tissues targeted by fungal pathogens. These findings offer a mechanistic basis for field practices and support the development of more effective and sustainable foliar spray formulations
Physical and Biological Measurements of Ethylene Emission Pinpoint the Importance of EIN4, EIN3 and EIL1 in the Regulation of Ethylene Biosynthesis in Arabidopsis Thaliana
No full textInternational audienceEthylene as a phytohormone affects many aspects of plant growth and development. To fully understand how ethylene functions in plants, it is essential to measure ethylene production over time and under different conditions. With this goal in mind, we developed a biological assay based on root hair length to screen large numbers of seedlings to determine their relative production of ethylene. This was coupled with a biophysical assay based on the specific detection of ethylene using near infra-red laser spectroscopy coupled to photoacoustic detection. With this sensitive method we examined the effects of light, relative headspace per seedling, and time of ethylene accumulation on rates of ethylene biosynthesis in Arabidopsis (Col). Our results indicate that Col rates of ethylene emission are positively affected by factors such as light but negatively regulated by a sealed environment. Interestingly, a 24h confinement in a sealed environment triggers typical ethylene dependent responses at the molecular level indicating that a decrease in ethylene emission may be the product of an activation of the signalling pathway. Taken together our data suggest that negative feedback regulation of ethylene biosynthesis relies on specific components of the ethylene signalling pathway and may involve a transcriptional regulation. Our observation opens fresh directions to explore the underlying mechanisms by which plants alter ethylene biosynthesis to regulate growth and development and highlight the importance of standardizing various factors when evaluating rates of ethylene biosynthesis
BReIF: une e-infrastructure pour accélérer l'utilisation de ressources biologiques diversifiées
No full textNational audienceLa caractérisation des ressources génétiques génère des quantités massives de données de nature très diverses qu’il faut analyser, gérer, rendre réutilisable et intégrer pour les transformer en connaissances mobilisables
Co-circulation and co-infection: parasite interactions across scales
No full textInternational audienceParasite–parasite interactions occur both within and between hosts, but the two scales are rarely considered together. Consequently, there is a gap in our ability to predict the integrated effects of interactions occurring across scales, disentangle their relative contributions to key ecological outcomes, and accurately identify the drivers of host–parasite evolutionary responses. Here, we extend the standard susceptible–infected framework of theoretical epidemiology to explicitly incorporate parasite–parasite interactions across scales. We identify where – in each step of the transmission process – such interactions may occur, at the within- or between-host levels, providing empirical examples where possible. Thus, we demonstrate how integrating the two scales provides a more complete understanding of the evolutionary ecology of multi-parasite systems and suggest future avenues of investigation
Les agents d’espaces naturels face aux changements socio-environnementaux et institutionnels : le cas des génépis dans le parc national du Mercantour
No full textDossier « Les professionnels de la montagne face aux changements socio-environnementaux »International audienceNational Parks legislation evolves in response to institutional, social and environmental changes. These protected areas interact with the actors who use and manage them and can thus be considered as social-ecological systems. The central position of national park agents in these systems makes them the sentinels of ecological and social dynamics in the park, although they also apply regulations that are not very dynamic. The management of heritage plants such as génépi stirs up contradictory views between users and managers. We focus here on the ‘génépi harvesting social-ecological system’, more precisely on how the agents of the Mercantour National Park experience the changes that affect this system. We describe how the Park agents observe and report changes in génépi populations, in harvesting practices, in their profession and in the National Park institution. This work highlights the diversity of the agents’ experiences, depending, among other things, on changes in the priorities regarding their different activities, the types of harvesters they meet, or their assessment of the effects of harvesting and the sensitivity of génépi species and overall changes in their activity. Three quarters of the agents surveyed consider that current génépi regulations are inadequate, partly because of the mismatch between regulations and institutional and social-environmental changes. The diversity of real-life situations that the National Park agents experience in relation to multiple changes underlines the need for a broader analysis of their profession that integrates ethnology, ecology and dynamic aspects to provide a more complete view of the social-ecological systems under study.Les législations mises en oeuvre dans les parcs nationaux évoluent au gré de changements institutionnels et socio-environnementaux. Ces territoires, en interaction avec les acteurs qui les utilisent ou les gèrent, peuvent être considérés comme des socio-écosystèmes. Les agents des parcs nationaux jouent un rôle central dans ces systèmes, en tant que sentinelles des dynamiques écologiques et sociales du parc, tout en ayant pour mission d'appliquer des réglementations peu dynamiques et parfois décalées. La gestion d'une plante patrimoniale comme le génépi attise des visions contradictoires entre utilisateurs et gestionnaires. Nous nous intéressons ici plus spécifiquement à la manière dont les agents du parc national du Mercantour vivent les changements affectant le socio-écosystème de « cueillette des génépis », que ce soit l'évolution des populations de génépi, des pratiques de cueillette, de leur métier ou de l'institution « parc national ». Les entretiens soulignent la diversité de vécus au sein de ce territoire, reflétée par les dysfonctionnements de la réglementation de cueillette que chaque agent identifie
