Phosphorus efficiency and innovation of phosphate fertilizers

Ce mémoire de validation des acquis de l’expérience (VAE) s’inscrit dans le cadre d’une demande d’accès au diplôme de doctorat. Il s’organise autour de trois parties. La première est un bilan de parcours, la deuxième est une analyse des activités de recherche et la troisième est un bilan des productions scientifiques. Autour de nombreux exemples, il structure une analyse des acquis et des compétences. Dans le premier chapitre, le bilan de parcours s’appuie sur une analyse chronologique et catégorielle des activités (travaux de recherche, animation scientifique, encadrement, enseignement, etc.) aussi bien en recherche publique que privée. Il rend compte de nombreuses évolutions sensibles : évolution du positionnement à la recherche, spécialisation progressive des sujets d’étude, internationalisation croissante des échanges scientifiques, structuration du réseau partenarial, management d’équipe…Dans le deuxième chapitre, plusieurs travaux scientifiques sont présentés portant sur l’amélioration de l’efficience d’utilisation du phosphore selon diverses approches (complexation, solubilisation bactérienne, voie de signalisation, vectorisation de principes actifs et modélisation de diffusion…). Ces sujets de recherche s’organisent autour de la compréhension des processus, des mécanismes d’actions et des domaines de validité des solutions à destination du milieu agricole. Enfin, dans le troisième chapitre, les types de productions scientifiques (publications, brevets, autorisations de mise sur le marché, posters, communications, rapports d’expertise…) rendent compte de la transThis manuscript is part of a process of recognition of acquired experience. It is organized around three parts. The first part is an assessment of the course, the second part is an analysis of the research activities and the third part is a review of the scientific productions. Around many examples, it structures an analysis of skills and competencies. In the first chapter, the assessment of the course is based on a chronological and categorical analysis of activities (research work, scientific animation, supervision, teaching, etc.) in both public and private research. It reports on many significant developments: evolution of positioning to research, progressive specialization of the subjects of study, increasing internationalization of scientific exchanges, structuring of the partnership network, team management ...In the second chapter, several scientific works are presented on the improvement of the efficiency of use of phosphorus according to various approaches (complexation, bacterial solubilization, signaling pathway, vectorization of active principles and diffusion modeling ...). These research topics are organized around the understanding of processes, mechanisms of action and areas of validity of solutions for the agricultural community. Finally, in the third chapter, the types of scientific productions (publications, patents, marketing authorizations, posters, communications, expert reports ...) reflect the transdisciplinary of the work, reveal the importance of protection strategies. intellectual property and concretize the complementary nature of the laborat

Using Data Science to Improve the Identification of Plant Nutritional Status

International audienceDeveloping products for improving plant nutritional status, e.g. fertilizers or plant growth regulators, is an important topic to move towards sustainability in agriculture and to ensure to feed the world population. A key challenge is to identify when, what, and how much nutrients to add to plants' growth environment. In this paper, we study a use case on how to characterize rapeseed plant nutrient deficiencies during their growth. A promising approach consists of deriving data from spectroscopy of leaves, and using this representation to predict what kind of deficiency (if any) plants are undergoing. We are considering three research questions: 1) from which day after onset of a nutrient deficiency we can identify it, 2) whether leaves that have sprouted under nutrient-rich conditions can still help in identifying problems. Third, and most importantly, performing the spectroscopy on the full range of wavelengths is expensive, which under production conditions allows for only relatively few samples. We therefore explore how to perform dimensionality reduction and preprocessing to achieve good predictive accuracy. We show that 1) deficiencies can be identified early on, 2) leaf generations help to predict nutrient deficiencies, and 3) that preprocessing increases the accuracy and dimensionality reduction can be performed without loss of accuracy. Along the way, we find that our some of our industry partners' assumptions about the data do not seem to be borne out by our empirical results, and that the subset of data they initially selected turns out to be too easy to model. The full data leads to more informative insights

Memory or acclimation of water stress in pea rely on root system's plasticity and plant's ionome modulation

International audienceIntroduction: Peas, as legume crops, could play a major role in the future of food security in the context of worldwide human nutrient deficiencies coupled with the growing need to reduce consumption of animal products. However, pea yields, in terms of quantity and quality (i.e. grain content), are both susceptible to climate change, and more specifically to water deficits, which nowadays occur more frequently during crop growth cycles and tend to last longer. The impact of soil water stress on plant development and plant growth is complex, as its impact varies depending on soil water availability (through the modulation of elements available in the soil), and by the plant's ability to acclimate to continuous stress or to memorize previous stress events. Method: To identify the strategies underlying these plant responses to water stress events, pea plants were grown in controlled conditions under optimal water treatment and different types of water stress; transient (during vegetative or reproductive periods), recurrent, and continuous (throughout the plant growth cycle). Traits related to water, carbon, and ionome uptake and uses were measured and allowed the identification typical plant strategies to cope with water stress. Conclusion: Our results highlighted (i) the common responses to the three types of water stress in shoots, involving manganese (Mn) in particular, (ii) the potential implications of boron (B) for root architecture modification under continuous stress, and (iii) the establishment of an "ecophysiological imprint" in the root system via an increase in nodule numbers during the recovery period

Transcriptomic, Metabolomic and Ionomic Analyses Reveal Early Modulation of Leaf Mineral Content in Brassica napus under Mild or Severe Drought

While it is generally acknowledged that drought is one of the main abiotic factors affecting plant growth, how mineral nutrition is specifically and negatively affected by water deficit has received very little attention, other than being analyzed as a consequence of reduced growth. Therefore, Brassica napus plants were subjected to a gradual onset of water deficits (mild, severe, or severe extended), and leaves were analyzed at the ionomic, transcriptomic and metabolic levels. The number of Differentially Expressed Genes (DEGs) and of the most differentially accumulated metabolites increased from mild (525 DEGs, 57 metabolites) to severe (5454 DEGs, 78 metabolites) and severe extended (9346 DEGs, 95 metabolites) water deficit. Gene ontology enrichment analysis of the 11,747 DEGs identified revealed that ion transport was one of the most significant processes affected, even under mild water deficit, and this was also confirmed by the shift in ionomic composition (mostly micronutrients with a strong decrease in Mo, Fe, Zn, and Mn in leaves) that occurred well before growth reduction. The metabolomic data and most of the transcriptomic data suggested that well-known early leaf responses to drought such as phytohormone metabolism (ABA and JA), proline accumulation, and oxidative stress defense were induced later than repression of genes related to nutrient transport

Systems for stimuli-controlled release: Materials and applications

International audienc

Specificity and Plasticity of the Functional Ionome of Brassica napus and Triticum aestivum Subjected to Macronutrient Deprivation

The composition of the functional ionome was studied in Brassica napus and Triticum aestivum with respect to the response of 20 elements under macronutrient deprivation. Analysis of relative root contents showed that some nutrients, such as Fe, Ni, Cu, Na, V, and Co, were largely sequestered in roots. After 10 days of deprivation of each one of these 6 macronutrients, plant growth was similar to control plants, and this was probably the result of remobilization from roots (Mg and Ca) or old leaves (N, P, K, S). Some tissue concentrations and net nutrient uptakes into roots were either decreased or increased, revealing multiple interactions (93 in wheat, 66 in oilseed rape) that were common to both species (48) or were species specific. While some interactions have been previously described (increased uptake of Na under K deficiency; or increased uptake of Mo and Se under S deficiency), a number of new interactions were found and some key mechanisms underlying their action have been proposed from analysis of Arabidopsis mutants. For example, nitrate uptake seemed to be functionally linked to Na(influx, while the uptake of vanadium was probably mediated by sulfate transporters whose expression was stimulated during S deprivation

Additive and Specific Effects of Elicitor Treatments on the Metabolic Profile of <i>Arabidopsis thaliana</i>

Several elicitors of plant defense have been identified and numerous efforts to use them in the field have been made. Exogenous elicitor treatments mimic the in planta activation of pattern-triggered immunity (PTI), which relies on the perception of pathogen-associated molecular patterns (PAMPs) such as bacterial flg22 or fungal chitins. Early transcriptional responses to distinct PAMPs are mostly overlapping, regardless of the elicitor being used. However, it remains poorly known if the same patterns are observed for metabolites and proteins produced later during PTI. In addition, little is known about the impact of a combination of elicitors on PTI and the level of induced resistance to pathogens. Here, we monitored Arabidopsis thaliana resistance to the bacterial pathogen Pseudomonas syringae pv. tomato DC3000 ( Pto DC3000) following application of flg22 and chitosan elicitors, used individually or in combination. A slight, but not statistically significant increase in induced resistance was observed when the elicitors were applied together when compared with individual treatments. We investigated the effect of these treatments on the metabolome by using an untargeted analysis. We found that the combination of flg22 and chitosan impacted a higher number of metabolites and deregulated specific metabolic pathways compared with the elicitors individually. These results contribute to a better understanding of plant responses to elicitors, which might help better rationalize their use in the field. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license

Uncoupling Aluminum Toxicity From Aluminum Signals in the STOP1 Pathway

International audienceAluminum (Al) is a major limiting factor for crop production on acidic soils, inhibiting root growth and plant development. At acidic pH (pH &lt; 5.5), Al 3+ ions are the main form of Al present in the media. Al 3+ ions have an increased solubility at pH &lt; 5.5 and result in plant toxicity. At higher pH, the free Al 3+ fraction decreases in the media, but whether plants can detect Al at these pHs remain unknown. To cope with Al stress, the SENSITIVE TO PROTON RHIZOTOXICITY1 (STOP1) transcription factor induces AL-ACTIVATED MALATE TRANSPORTER1 ( ALMT1 ), a malate-exuding transporter as a strategy to chelate the toxic ions in the rhizosphere. Here, we uncoupled the Al signalling pathway that controls STOP1 from Al toxicity using wild type (WT) and two stop1 mutants carrying the pALMT1:GUS construct with an agar powder naturally containing low amounts of phosphate, iron (Fe), and Al. We combined gene expression [real-time PCR (RT-PCR) and the pALMT1:GUS reporter], confocal microscopy ( pSTOP1:GFP-STOP1 reporter), and root growth measurement to assess the effects of Al and Fe on the STOP1-ALMT1 pathway in roots. Our results show that Al triggers STOP1 signaling at a concentration as little as 2 μM and can be detected at a pH above 6.0. We observed that at pH 5.7, 20 μM AlCl 3 induces ALMT1 in WT but does not inhibit root growth in stop1 Al-hypersensitive mutants. Increasing AlCl 3 concentration (&gt;50 μM) at pH 5.7 results in the inhibition of the stop1 mutants primary root. Using the green fluorescent protein (GFP)-STOP1 and ALMT1 reporters, we show that the Al signal pathway can be uncoupled from the Al toxicity on the root. Furthermore, we observe that Al strengthens the Fe-mediated inhibition of primary root growth in WT, suggesting an interaction between Fe and Al on the STOP1-ALMT1 pathway

Uncoupling Aluminum Toxicity From Aluminum Signals in the STOP1 Pathway

International audienceAluminum (Al) is a major limiting factor for crop production on acidic soils, inhibiting root growth and plant development. At acidic pH (pH &lt; 5.5), Al 3+ ions are the main form of Al present in the media. Al 3+ ions have an increased solubility at pH &lt; 5.5 and result in plant toxicity. At higher pH, the free Al 3+ fraction decreases in the media, but whether plants can detect Al at these pHs remain unknown. To cope with Al stress, the SENSITIVE TO PROTON RHIZOTOXICITY1 (STOP1) transcription factor induces AL-ACTIVATED MALATE TRANSPORTER1 ( ALMT1 ), a malate-exuding transporter as a strategy to chelate the toxic ions in the rhizosphere. Here, we uncoupled the Al signalling pathway that controls STOP1 from Al toxicity using wild type (WT) and two stop1 mutants carrying the pALMT1:GUS construct with an agar powder naturally containing low amounts of phosphate, iron (Fe), and Al. We combined gene expression [real-time PCR (RT-PCR) and the pALMT1:GUS reporter], confocal microscopy ( pSTOP1:GFP-STOP1 reporter), and root growth measurement to assess the effects of Al and Fe on the STOP1-ALMT1 pathway in roots. Our results show that Al triggers STOP1 signaling at a concentration as little as 2 μM and can be detected at a pH above 6.0. We observed that at pH 5.7, 20 μM AlCl 3 induces ALMT1 in WT but does not inhibit root growth in stop1 Al-hypersensitive mutants. Increasing AlCl 3 concentration (&gt;50 μM) at pH 5.7 results in the inhibition of the stop1 mutants primary root. Using the green fluorescent protein (GFP)-STOP1 and ALMT1 reporters, we show that the Al signal pathway can be uncoupled from the Al toxicity on the root. Furthermore, we observe that Al strengthens the Fe-mediated inhibition of primary root growth in WT, suggesting an interaction between Fe and Al on the STOP1-ALMT1 pathway