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International audience; How specific interactions between plant and pathogenic, commensal, or mutualistic microorganisms are mediated and how bacteria are selected by a plant are important questions to address. Here, an Arabidopsis thaliana mutant called chs5 partially deficient in the biogenesis of isoprenoid precursors was shown to extend its metabolic remodeling to phenylpropanoids and lipids in addition to carotenoids, chlorophylls, and terpenoids. Such a metabolic profile was concomitant to increased colonization of the phyllosphere by the pathogenic strain Pseudomonas syringae pv. tomato DC3000. A thorough microbiome analysis by 16S sequencing revealed that Streptomyces had a reduced colonization potential in chs5. This study revealed that the bacteria–Arabidopsis interaction implies molecular processes impaired in the chs5 mutant. Interestingly, our results revealed that the metabolic status of A. thaliana was crucial for the specific recruitment of Streptomyces into the microbiota. More generally, this study highlights specific as well as complex molecular interactions that shape the plant microbiota.

How specific interactions between plant and pathogenic, commensal, or mutualistic microorganisms are mediated and how bacteria are selected by a plant are important questions to address. Here, an

Background and purpose COVID‐19 affects the brain in various ways, amongst which delirium is worrying. An assessment was made of whether a specific, long‐lasting, COVID‐19‐related brain injury develops in acute respiratory distress syndrome patients after life‐saving re‐oxygenation. Methods Ten COVID+ patients (COVID+) with unusual delirium associated with neuroimaging suggestive of diffuse brain injury and seven controls with non‐COVID encephalopathy were studied. The assessment took place when the intractable delirium started at weaning off ventilation support. Brain magnetic resonance imaging (MRI) was performed followed by standard cerebrospinal fluid (CSF) analyses and assessment of CSF erythropoietin concentrations (as a marker for the assessment of tissue repair), and of non‐targeted CSF metabolomics using liquid chromatography high resolution mass spectrometry. Results Patients were similar as regards severity scores, but COVID+ were hospitalized longer (25 [11.75; 25] vs. 9 [4.5; 12.5] days, p = 0.03). On admission, but not at MRI and lumbar puncture performance, COVID+ were more hypoxic (p = 0.002). On MRI, there were leptomeningeal enhancement and diffuse white matter haemorrhages only in COVID+. In the latter, CSF erythropoietin concentration was lower (1.73 [1.6; 2.06] vs. 3.04 [2.9; 3.91] mIU/ml, p = 0.01), and CSF metabolomics indicated (a) increased compounds such as foodborne molecules (sesquiterpenes), molecules from industrialized beverages and micro‐pollutants (diethanolamine); and (b) decreased molecules such as incomplete breakdown products of protein catabolism and foodborne molecules (glabridin). At 3‐month discharge, fatigue, anxiety and depression as well as MRI lesions persisted in COVID+. Conclusions Some COVID+ are at risk of a specific delirium. Imperfect brain repair after re‐oxygenation and lifestyle factors might influence long‐lasting brain injuries in a context of foodborne micro‐pollutants., This explorative cohort study suggests that life‐saving re‐oxygenation of COVID+ patients is possibly followed by an incomplete brain repair as indicated by magnetic resonance imaging and low cerebrospinal fluid erythropoietin (CSF EPO) concentrations. In addition, non‐targeted metabolomics analysis identified the presence of many perturbed metabolites during COVID‐induced delirium, including biomarkers for the consumption of specific food and intermediate factors that have tangible impact on inflammatory pathways.

Position within the social group has consequences on individual lifespans in diverse taxa. This is especially obvious in eusocial insects, where workers differ in both the tasks they perform and their aging rates. However, in eusocial wasps, bees and ants, the performed task usually depends strongly on age. As such, untangling the effects of social role and age on worker physiology is a key step towards understanding the coevolution of sociality and aging. We performed an experimental protocol that allowed a separate analysis of these two factors using four groups of black garden ant (Lasius niger) workers: young foragers, old foragers, young nest workers, and old nest workers. We highlighted age-related differences in the proteome and metabolome of workers that were primarily related to worker subcaste and only secondarily to age. The relative abundance of proteins and metabolites suggests an improved xenobiotic detoxification, and a fuel metabolism based more on lipid use than carbohydrate use in young ants, regardless of their social role. Regardless of age, proteins related to the digestive function were more abundant in nest workers than in foragers. Old foragers were mostly characterized by weak abundances of molecules with an antibiotic activity or involved in chemical communication. Finally, our results suggest that even in tiny insects, extended lifespan may require to mitigate cancer risks. This is consistent with results found in eusocial rodents and thus opens up the discussion of shared mechanisms among distant taxa and the influence of sociality on life history traits such as longevity.

Position within the social group has consequences on individual lifespans in diverse taxa. This is especially obvious in eusocial insects, where workers differ in both the tasks they perform and their aging rates. However, in eusocial wasps, bees and ants, the performed task usually depends strongly on age. As such, untangling the effects of social role and age on worker physiology is a key step towards understanding the coevolution of sociality and aging. We performed an experimental protocol that allowed a separate analysis of these two factors using four groups of black garden ant (Lasius niger) workers: young foragers, old foragers, young nest workers, and old nest workers. We highlighted age-related differences in the proteome and metabolome of workers that were primarily related to worker subcaste and only secondarily to age. The relative abundance of proteins and metabolites suggests an improved xenobiotic detoxification, and a fuel metabolism based more on lipid use than carbohydrate use in young ants, regardless of their social role. Regardless of age, proteins related to the digestive function were more abundant in nest workers than in foragers. Old foragers were mostly characterized by weak abundances of molecules with an antibiotic activity or involved in chemical communication. Finally, our results suggest that even in tiny species, extended lifespan may require to mitigate cancer risks. This is consistent with results found in eusocial rodents and thus opens up the discussion of shared mechanisms among distant taxa and the influence of sociality on life history traits such as longevity.

Microbial populations associated to poplar are well described in non-contaminated and metal-contaminated environments but more poorly in the context of polycyclic aromatic hydrocarbon (PAH) contamination. This study aimed to understand how a gradient of phenanthrene (PHE) contamination affects poplar growth and the fungal microbiome in both soil and plant endosphere (roots, stems and leaves). Plant growth and fitness parameters indicated that the growth of Populus canadensis was impaired when PHE concentration increased above 400 mg kg−1. Values of alpha-diversity indicators of fungal diversity and richness were not affected by the PHE gradient. The PHE contamination had a stronger impact on the fungal community composition in the soil and root compartments compared to that of the aboveground organs. Most of the indicator species whose relative abundance was correlated with PHE contamination decreased along the gradient indicating a toxic effect of PHE on these fungal OTUs (Operational Taxonomic Units). However, the relative abundance of some OTUs such as Cadophora, Alternaria and Aspergillus, potentially linked to PHE degradation or being plant-beneficial taxa, increased along the gradient. Finally, this study allowed a deeper understanding of the dual response of plant and fungal communities in the case of a soil PAH contamination gradient leading to new perspectives on fungal assisted phytoremediation.

International audience; Ultrahigh resolution mass spectrometry (UHR-MS) coupled with direct infusion (DI) electrospray ionization offers a fast solution for accurate untargeted profiling. Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometers have been shown to produce a wealth of insights into complex chemical systems because they enable unambiguous molecular formula assignment even if the vast majority of signals is of unknown identity. Interlaboratory comparisons are required to apply this type of instrumentation in quality control (for food industry or pharmaceuticals), large-scale environmental studies, or clinical diagnostics. Extended comparisons employing different FT-ICR MS instruments with qualitative direct infusion analysis are scarce since the majority of detected compounds cannot be quantified. The extent to which observations can be reproduced by different laboratories remains unknown. We set up a preliminary study which encompassed a set of 17 laboratories around the globe, diverse in instrumental characteristics and applications, to analyze the same sets of extracts from commercially available standard human blood plasma and Standard Reference Material (SRM) for blood plasma (SRM1950), which were delivered at different dilutions or spiked with different concentrations of pesticides. The aim of this study was to assess the extent to which the outputs of differently tuned FT-ICR mass spectrometers, with different technical specifications, are comparable for setting the frames of a future DI-FT-ICR MS ring trial. We concluded that a cluster of five laboratories, with diverse instrumental characteristics, showed comparable and representative performance across all experiments, setting a reference to be used in a future ring trial on blood plasma.

The social organization of many primate, bird and rodent species and the role of individuals within that organization are associated with specific individual physiological traits. However, this association is perhaps most pronounced in eusocial insects (e.g., termites, ants). In such species, genetically close individuals show significant differences in behavior, physiology, and life expectancy. Studies addressing the metabolic changes according to the social role are still lacking. We aimed at understanding how sociality could influence essential molecular processes in a eusocial insect, the black garden ant (Lasius niger) where queens can live up to ten times longer than workers. Using mass spectrometry-based analysis, we explored the whole metabolome of queens, nest-workers and foraging workers. A former proteomics study done in the same species allowed us to compare the findings of both approaches. Confirming the former results at the proteome level, we showed that queens had fewer metabolites related to immunity. Contrary to our predictions, we did not find any metabolite linked to reproduction in queens. Among the workers, foragers had a metabolic signature reflecting a more stressful environment and a more highly stimulated immune system. We also found that nest-workers had more digestion-related metabolites. Hence, we showed that specific metabolic signatures match specific social roles. Besides, we identified metabolites differently expressed among behavioral castes and involved in nutrient sensing and longevity pathways (e.g., sirtuins, FOXO). The links between such molecular pathways and aging being found in an increasing number of taxa, our results confirm and strengthen their potential universality.

International audience; Background: Hypertension is a major cardiovascular risk factor that affects most countries including those of Africa. Although Carissa edulis Vahl, Diodia scandens Sw. and Cleome gynandra L. are traditionally used in Benin as antihypertensive treatments with some efficacy mentioned by the local population, their biological activity on the cardiovascular system remains poorly studied.Aim: The study investigated the vasoreactivity of the plants and assessed the underlying mechanisms using isolated arteries.Study design: Aqueous-ethanolic extracts of aerial parts of C. edulis, D. scandens and C. gynandra were prepared by maceration before being subjected to multi-step liquid-liquid fractionation with solvents of increasing polarity. The vasoreactivity of the extracts and fractions were assessed on isolated porcine coronary artery and rat aorta using organ chambers, the role of nitric oxide (NO) using NG-nitro-L-arginine (NO synthase inhibitor), prostanoids using indomethacin (cyclooxygenases inhibitor) and endothelium-dependent hyperpolarization using TRAM-34 plus UCL 1684 (inhibitors of calcium-dependent K+ channels), and the vascular uptake of polyphenols using Neu reagent.Results: The aqueous-ethanolic crude extract of C. edulis (CECE) induced potent relaxations that were exclusively endothelium-dependent and more pronounced than those to D. scandens and C. gynandra. The n-butanolic fraction of C. edulis (CEBF) was more active than the cyclohexane, dichloromethane, and ethyl acetate fractions. The relaxation induced by CECE and CEBF were inhibited by NG-nitro-L-arginine and affected neither by TRAM-34 plus UCL 1684 nor by indomethacin. CEBF induced sustained endothelium-dependent relaxations for at least 60 min, and inhibited, in a concentration-dependent manner, contractions to KCl, CaCl2, U46619 and serotonin in rings with endothelium. Analysis of CEBF by LCsingle bondHRMS indicated the presence of polyphenols, terpenes, and alkaloids. Exposure of coronary artery and aorta rings to CEBF caused the accumulation of polyphenols predominantly in the endothelium.Conclusion: C. edulis leaf extract induced pronounced endothelium-dependent relaxations and inhibited contractile responses by stimulating the endothelial formation of NO. LCsingle bondHRMS analysis of the most active fraction, the butanolic fraction, revealed the presence of numerous compounds including polyphenols, terpenes, and alkaloids. The polyphenols of CEBF accumulated preferentially in the endothelium of the arterial wall. Thus, these observations support the folkloric use of C. edulis in hypertension.

In human society, there is a demand for sustainable solutions for water preservation and efficient treatment systems. An important water reservoir is road runoff defined as rainwater leaching from roads, loading micropollutants and infiltrating the soil. We aimed to study this poorly understood feature using large-scale metabolomic analysis coupled with analysis of soil physico-chemical properties and molecular chemical similarity enrichment. A total of 2406 micropollutants were assayed to understand their distribution and assess the trapping abilities of a road runoff infiltration system composed of a sedimentation pond and an infiltration pond. Here, we confirm the essential role of the infiltration pond in preventing environmental contamination and propose a model correlating micropollutant abundance and the soil physico-chemical properties. We demonstrate that sand in infiltration ponds is a key player, helping retain 86% of the micropollutant abundance and propose a model that could be easily applied for road runoff management.

Jasmonate signaling for adaptative or developmental responses generally relies on an increased synthesis of the bioactive hormone jasmonoyl-isoleucine (JA-Ile), triggered by environmental or internal cues. JA-Ile is embedded in a complex metabolic network whose upstream and downstream components strongly contribute to hormone homeostasis and activity. We previously showed that JAO2, an isoform of four Arabidopsis JASMONIC ACID OXIDASES, diverts the precursor jasmonic acid (JA) to its hydroxylated form HO-JA to attenuate JA-Ile formation and signaling. Consequently, JAO2-deficient lines have elevated defenses and display improved tolerance to biotic stress. Here we further explored the organization and regulatory functions of the JAO pathway. Suppression of JAO2 enhances the basal expression of nearly 400 JA-regulated genes in unstimulated leaves, many of which being related to biotic and abiotic stress responses. Consistently, non-targeted metabolomic analysis revealed the constitutive accumulation of several classes of defensive compounds in jao2-1 mutant, including indole glucosinolates and breakdown products. The most differential compounds were agmatine phenolamides, but their genetic suppression did not alleviate the strong resistance of jao2-1 to Botrytis infection. Furthermore, jao2 alleles and a triple jao mutant exhibit elevated survival capacity upon severe drought stress. This latter phenotype occurs without recruiting stronger abscisic acid responses, but relies on enhanced JA-Ile signaling directing a distinct survival pathway with MYB47 transcription factor as a candidate mediator. Our findings reveal the selected spectrum of JA responses controlled by the JAO2 regulatory node and highlight the potential of modulating basal JA turnover to pre-activate mild transcriptional programs for multiple stress resilience.

Nitrate, one of the main nitrogen (N) sources for crops, acts as a nutrient and key signaling molecule coordinating gene expression, metabolism and various growth processes throughout the plant life cycle. It is widely accepted that nitrate-triggered developmental programs cooperate with hormone synthesis and transport, to finely adapt plant architecture to N availability. Here, we report that nitrate, acting through its signaling pathway, promotes growth in Arabidopsis and wheat, in part by modulating the accumulation of gibberellin (GA)-regulated DELLA growth repressors. We show that nitrate reduces the abundance of DELLAs by increasing GA contents through activation of GA metabolism gene expression. Consistently, the growth restraint conferred by nitrate deficiency is partially rescued in global-DELLA mutant that lacks all DELLAs. At the cellular level, we show that nitrate enhances both cell proliferation and elongation in a DELLA-dependent and -independent manner, respectively. Our findings establish a connection between nitrate and GA signaling pathways that allow plants to adapt their growth to nitrate availability.

International audience; Conventional wastewater treatment plants are not designed to treat micropollutants; thus, for 20 years, several complementary treatment systems, such as surface flow wetlands have been used to address this issue. Previous studies demonstrate that higher residence time and low global velocities promote nutrient removal rates or micropollutant photodegradation. Nevertheless, these studies were restricted to the system limits (inlet/outlet). Therefore, detailed knowledge of water flow is crucial for identifying areas that promote degradation and optimise surface flow wetlands. The present study combines 3D water flow numerical modelling and liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS/MS). Using this numerical model, validated by tracer experimental data, several velocity areas were distinguished in the wetland. Four areas were selected to investigate the waterflow influence and led to the following results: on the one hand, the number and concentration of micropollutants are independent of the waterflow, which could be due to several assumptions, such as the chronic exposure associated with a low Reynolds number; on the other hand, the potential degradation products (metabolites) were also assessed in the sludge to investigate the micropollutant biodegradation processes occurring in the wetland; micropollutant metabolites or degradation products were detected in higher proportions (both number and concentration) in lower flow rate areas. The relation to higher levels of plant and microorganism metabolites suggests higher biological activity that promotes degradation.

To investigate mechanisms by which hibernators avoid atherogenic hyperlipidemia during hibernation, we assessed lipoprotein and cholesterol metabolisms of free-ranging Scandinavian brown bears (Ursus arctos). In winter- and summer-captured bears, we measured lipoprotein sizes and sub-classes, triglyceride-related plasma-enzyme activities, and muscle lipid composition along with plasma-levels of antioxidant capacities and inflammatory markers. Although hibernating bears increased nearly all lipid levels, a 36%-higher cholesteryl-ester transfer-protein activity allowed to stabilize lipid composition of high-density lipoproteins (HDL). Levels of inflammatory metabolites, i.e., 7-ketocholesterol and 11ß-prostaglandin F2α, declined in winter and correlated inversely with cardioprotective HDL2b-proportions and HDL-sizes that increased during hibernation. Lower muscle-cholesterol concentrations and lecithin-cholesterol acyltransferase activity in winter suggest that hibernating bears tightly controlled peripheral-cholesterol synthesis and/or release. Finally, greater plasma-antioxidant capacities prevented excessive lipid-specific oxidative damages in plasma and muscles of hibernating bears. Hence, the brown bear manages large lipid fluxes during hibernation, without developing adverse atherogenic effects that occur in humans and non-hibernators.

International audience; Sulfur metabolism in fuel-biodesulfurizing bacteria and the underlying physiological adaptations are not understood, which has impeded the development of a commercially viable bioprocess for fuel desulfurization. To fill these knowledge gaps, we performed comparative proteomics and untargeted metabolomics in cultures of the biodesulfurization reference strain Rhodococcus qingshengii IGTS8 grown on either inorganic sulfate or the diesel-borne organosulfur compound dibenzothiophene as a sole sulfur source. Dibenzothiophene significantly altered the biosynthesis of many sulfur metabolism proteins and metabolites in a growth phase-dependent manner, which enabled us to reconstruct the first experimental model for sulfur metabolism in a fuel-biodesulfurizing bacterium. All key pathways related to assimilatory sulfur metabolism were represented in the sulfur proteome, including uptake of the sulfur sources, sulfur acquisition, and assimilatory sulfate reduction, in addition to biosynthesis of key sulfur-containing metabolites such as S-adenosylmethionine, coenzyme A, biotin, thiamin, molybdenum cofactor, mycothiol, and ergothioneine (low-molecular weight thiols). Fifty-two proteins exhibited significantly different abundance during at least one growth phase. Sixteen proteins were uniquely detected and 47 proteins were significantly more abundant in the dibenzothiophene culture during at least one growth phase. The sulfate-free dibenzothiophene-containing culture reacted to sulfate starvation by restricting sulfur assimilation, enforcing sulfur-sparing, and maintaining redox homeostasis. Biodesulfurization triggered alternative pathways for sulfur assimilation different from those operating in the inorganic sulfate culture. Sulfur metabolism reprogramming and metabolic switches in the dibenzothiophene culture were manifested in limiting sulfite reduction and biosynthesis of cysteine, while boosting the production of methionine via the cobalamin-independent pathway, as well as the biosynthesis of the redox buffers mycothiol and ergothioneine. The omics data underscore the key role of sulfur metabolism in shaping the biodesulfurization phenotype and highlight potential targets for improving the biodesulfurization catalytic activity via metabolic engineering. IMPORTANCE For many decades, research on biodesulfurization of fossil fuels was conducted amid a large gap in knowledge of sulfur metabolism and its regulation in fuel-biodesulfurizing bacteria, which has impeded the development of a commercially viable bioprocess. In addition, lack of understanding of biodesulfurization-associated metabolic and physiological adaptations prohibited the development of efficient biodesulfurizers. Our integrated omics-based findings reveal the assimilatory sulfur metabolism in the biodesulfurization reference strain Rhodococcus qingshengii IGTS8 and show how sulfur metabolism and oxidative stress response were remodeled and orchestrated to shape the biodesulfurization phenotype. Our findings not only explain the frequently encountered low catalytic activity of native fuel-biodesulfurizing bacteria but also uncover unprecedented potential targets in sulfur metabolism that could be exploited via metabolic engineering to boost the biodesulfurization catalytic activity, a prerequisite for commercial application.

Wastewater is one of the major sources of micropollutant release into the environment. In order to reduce the impact of wastewater, wastewater treatment plants (WWTP) have been set up, in the instance of vertical flow constructed wetlands (VFCWs). Besides, micropollutants could represent a vast diversity of compounds and compound's choice could bias studies focused on their fate. To overcome this bias, non-targeted screening approaches can be performed. Therefore, the diffusion of micropollutants from raw wastewater in the VFCW compartments (wastewater, plants and sludge) as well as their fate have been investigated using this non-target approach with liquid chromatography (LC) coupled to high resolution mass spectrometry (HRMS) and gas chromatography (GC) coupled to mass spectrometry. To help the operators in their sludge management, this study will be focused on the following question: Is there a specific distribution of micropollutants according to sludge layers? To eliminate the background contamination found both inside the CW and in the surrounding environment, a control coring was performed in bank. A specific distribution could be observed in the top (191 compounds) and bottom layers (38 compounds). However, a distribution over the whole depth for xenobiotics was observed. Micropollutants classes and the main microbial productivity were preferably found in the top layer. The micropollutants fate could however not be restricted to the sludge compartment. Therefore, the specific micropollutants distribution was analyzed in the outputs of the system in their interactions with wastewater (effluent, sludge, and reed rhizomes) to understand their fate. In our study, the results highlighted a consistent part of compounds found in at least two or three of these compartments, with a similar trend in each compartment. These results underline the interactions between the compartments and the global issues of micropollutants distribution as well as its wide spreading in the whole CW ecosystem.

To improve and complete our knowledge of archaeal tRNA modification patterns, we have identified and compared the modification pattern (type and location) in tRNAs of three very different archaeal species, Methanococcus maripaludis (a mesophilic methanogen), Pyrococcus furiosus (a hyperthermophile thermococcale), and Sulfolobus acidocaldarius (an acidophilic thermophilic sulfolobale). Most abundant isoacceptor tRNAs (79 in total) for each of the 20 amino acids were isolated by two-dimensional gel electrophoresis followed by in-gel RNase digestions. The resulting oligonucleotide fragments were separated by nanoLC and their nucleotide content analyzed by mass spectrometry (MS/MS). Analysis of total modified nucleosides obtained from complete digestion of bulk tRNAs was also performed. Distinct base- and/or ribose-methylations, cytidine acetylations, and thiolated pyrimidines were identified, some at new positions in tRNAs. Novel, some tentatively identified, modifications were also found. The least diversified modification landscape is observed in the mesophilic Methanococcus maripaludis and the most complex one in Sulfolobus acidocaldarius Notable observations are the frequent occurrence of ac4C nucleotides in thermophilic archaeal tRNAs, the presence of m7G at positions 1 and 10 in Pyrococcus furiosus tRNAs, and the use of wyosine derivatives at position 37 of tRNAs, especially those decoding U1- and C1-starting codons. These results complete those already obtained by others with sets of archaeal tRNAs from Methanocaldococcus jannaschii and Haloferax volcanii., SCOPUS: ar.j, info:eu-repo/semantics/published

Fragile X syndrome (FXS), the leading cause of familial intellectual disability, is an uncured disease caused by the absence or loss of function of the FMRP protein. FMRP is an RNA binding protein that controls the translation of specific proteins in neurons. A main target of FMRP in neurons is diacylglycerol kinase kappa (DGKk) and the loss of FMRP leads to a loss of DGK activity causing a diacylglycerol excess in the brain. Excessive diacylglycerol signaling could be a significant contributor to the pathomechanism of FXS. Here we tested the contribution of DAG-signaling inFmr1-KO mouse model of FXS and we show that pioglitazone, a widely prescribed drug for type 2 diabetes, has ability to correct excessive DAG signaling in the brain and rescue behavioral alterations of theFmr1-KO mouse. This study highlights the role of lipid signaling homeostasis in FXS and provides arguments to support the testing of pioglitazone for treatment of FXS.

Synthetic biology has potential spaceflight applications yet few if any studies have attempted to translate Earth-based synthetic biology tools into spaceflight. An exogenously inducible biological circuit for protein production in Arabidopsis thaliana, pX7-AtPDSi (Guo et al. 2003), was flown to ISS and functionally investigated. Seedlings were grown in a custom built 1.25 U plant greenhouse. Images recorded during the experiment show that leaves of pX7-AtPDSi seedlings photobleached as designed while wild type Col-0 leaves did not, which reveals that the synthetic circuit led to protein production during spaceflight. Polymerase chain reaction analysis post-flight also confirms that the Cre/LoxP (recombination system) portions of the circuit were functional in spaceflight. The subcomponents of the biological circuit, estrogen-responsive transcription factor XVE, Cre/LoxP DNA recombination system, and RNAi post-transcriptional gene silencing system now have flight heritage and can be incorporated in future designs for space applications. To facilitate future plant studies in space, the full payload design and manufacturing files are made available.

International audience; Rhodococcus strain IGTS8 is the most extensively studied model bacterium for biodesulfurization of fossil fuels via the non-destructive sulfur-specific 4S pathway. This strain was initially assigned to Rhodococcus rhodochrous and later to Rhodococcus erythropolis thus making its taxonomic status debatable and reflecting the limited resolution of methods available at the time. In this study, phylogenomic analyses of the whole genome sequences of strain IGTS8 and closely related rhodococci showed that R. erythropolis and Rhodococcus qingshengii are very closely related species, that Rhodococcus strain IGTS8 is a R. qingshengii strain and that several strains identified as R. erythropolis should be reclassified as R. qingshengii. The genomes of strains assigned to these species contain potentially novel biosynthetic gene clusters showing that members of these taxa should be given greater importance in the search for new antimicrobials and other industrially important biomolecules. The plasmid-borne dsz operon encoding fossil fuel desulfurization enzymes was present in R. qingshengii IGTS8 and R. erythropolis XP suggesting that it might be transferable between members of these species.

The method presented uses mass spectrometry imaging (MSI) to establish the metabolic profile of S. alba leaves when exposed to xenobiotics. Using a non-targeted approach, plant metabolites and xenobiotics of interest are identified and localized in plant tissues to uncover specific distribution patterns. Then, in silico prediction of potential metabolites (i.e., catabolites and conjugates) from the identified xenobiotics is performed. When a xenobiotic metabolite is located in the tissue, the type of enzyme involved in its alteration by the plant is recorded. These results were used to describe different types of biological reactions occurring in S. alba leaves in response to xenobiotic accumulation in the leaves. The metabolites were predicted in two generations, allowing the documentation of successive biological reactions to transform xenobiotics in the leaf tissues.

The method presented uses mass spectrometry imaging (MSI) to establish the metabolic profile of S. alba leaves when exposed to xenobiotics. Using a non-targeted approach, plant metabolites and xenobiotics of interest are identified and localized in plant tissues to uncover specific distribution patterns. Then, in silico prediction of potential metabolites (i.e., catabolites and conjugates) from the identified xenobiotics is performed. When a xenobiotic metabolite is located in the tissue, the type of enzyme involved in its alteration by the plant is recorded. These results were used to describe different types of biological reactions occurring in S. alba leaves in response to xenobiotic accumulation in the leaves. The metabolites were predicted in two generations, allowing the documentation of successive biological reactions to transform xenobiotics in the leaf tissues.

All plant α-tubulins encode a C-terminal tyrosine. An elusive tubulin tyrosine carboxypeptidase can cleave off, and a tubulin tyrosine ligase (TTL) re-ligate this tyrosine. The biological function of this cycle remains unclear but may correlate with microtubule stability. To get insight into the functional context of this phenomenon, we used cold-induced elimination of microtubules as experimental model. In previous work, we had analysed a rice TTL-like 12 (OsTTLL12), the only potential candidate of plant TTL. To follow the effect of OsTTLL12 upon microtubule responses in vivo, we expressed OsTTLL12-RFP into tobacco BY-2 cells stably overexpressing NtTUA3-GFP. We found that overexpression of OsTTLL12-RFP made microtubules disappear faster in response to cold stress, accompanied with more rapid Ca

Surface flow treatment wetlands (SFTW) are considered as ecological engineering treatment wetlands used for wastewater and stormwater treatment. In France SFTW are commonly located between the wastewater treatment plant (WWTP) and the receiving aquatic environment. Furthermore, they are not considered as a regulatory treatment step but as a complementary element to WWTP. In this regard, there is currently no established design and sizing rule since (i) they are built on the remaining space after WWTP construction, (ii) it is a nature-based system, subject to high variability and complex interactions and (iii) feedback on ageing effects is lacking. This study permitted to qualify and to quantify seasonal and ageing effects on the SFTW hydraulic behavior which is a pond. The combination of fluorescent dye tracer application in a real system and data analysis by dynamic time warping (DTW) allowed to perform efficiency comparisons between all campaigns. Similar behaviors of dimensionless retention time distributions were observed for all campaigns. They were eventually linked with the SFTW shape. The analysis of these curves highlighted that the measured mean residence time was always lower than the nominal hydraulic residence time, due to preferential flow and dead-zones. A statistical approach suggested that the winter hydraulic behavior was characterized by the highest short-cutting index and strongest convective flow regime in comparison to others campaigns. A lower vegetation density, especially subaquatic plants, and presence of important preferential flow could explain this observation. DTW processing on RTD curves shed light on the ageing effect that has a much bigger impact than seasonal effect. This is mainly due to sediments accumulation, sludge and vegetation development.

Phosphatidic acid (PA) is the simplest phospholipid naturally existing in living organisms, but it constitutes only a minor fraction of total cell lipids. PA has attracted considerable attention because it is a phospholipid precursor, a lipid second messenger, and a modulator of membrane shape, and it has thus been proposed to play key cellular functions. The dynamics of PA in cells and in subcellular compartments, however, remains an open question. The recent generation of fluorescent probes for PA, by fusing GFP to PA-binding domains, has provided direct evidence for PA dynamics in different intracellular compartments. Here, three PA sensors were characterized in vitro, and their preferences for different PA species in particular lipidic environments were compared. In addition, the localization of PA in macrophages during frustrated phagocytosis was examined using these PA sensors and was combined with a lipidomic analysis of PA in intracellular compartments. The results indicate that the PA sensors display some preferences for specific PA species, depending on the lipid environment, and the localization study in macrophages revealed the complexity of intracellular PA dynamics.

International audience; Plants are able to sense a rise in temperature of several degrees, and appropriately adapt their metabolic and growth processes. To this end, plants produce various signalling molecules that act throughout the plant body. Here, we report that root-derived GA$_{12}$, a precursor of the bioactive gibberellins, mediates thermo-responsive shoot growth in $Arabidopsis$. Our data suggest that root-to-shoot translocation of GA$_{12}$ enables a flexible growth response to ambient temperature changes.

Metabolites, lipids, and other small molecules are key constituents of tissues supporting cellular programs in health and disease. Here, we present METASPACE, a community-populated knowledge base of spatial metabolomes from imaging mass spectrometry data. METASPACE is enabled by a high-performance engine for metabolite annotation in a confidence-controlled way that makes results comparable between experiments and laboratories. By sharing their results publicly, engine users continuously populate a knowledge base of annotated spatial metabolomes in tissues currently including over 3000 datasets from human cancer cohorts, whole-body sections of animal models, and various organs. The spatial metabolomes can be visualized, explored and shared using a web app as well as accessed programmatically for large-scale analysis. By using novel computational methods inspired by natural language processing, we illustrate that METASPACE provides molecular coverage beyond the capacity of any individual laboratory and opens avenues towards comprehensive metabolite atlases on the levels of tissues and organs.

The metabolome, final downstream product of the genome and exogenous sources, is characterized by a large number of small molecules exhibiting a huge diversity of chemical structures and abundances, requiring complementary analytical platforms to reach its extensive coverage. The metabolome is dynamic, reflecting the continuous fluxes of metabolic and signalling pathways. Metabolomics is the detection and quantitation of metabolites in biological samples. Furthermore, recently emerged technologies have enabled us to determine spatiotemporal distribution of biological molecules present in tissues. In a two-part article, we present a description of usual metabolomics technologies, workflows and strategies leading to the implementation of new clinical biomarkers. In this first part, after introducing metabolomics concepts, we review analytical techniques used in this setting.

Micropollutants are increasingly monitored as their presence in the environment is rising due to human activities, and they are potential threats to living organisms. This study aimed at understanding the role of plants in xenobiotics removal from polluted environments by following xenobiotics metabolism in leaf tissues. Different classes of micropollutants were investigated using liquid chromatography (LC) coupled to quadrupole-time of flight (Q-TOF) high resolution mass spectrometry (HRMS). The tissue localization of xenobiotics in the leaves of a spontaneous (not planted by humans) Salix alba growing near the water flux was further investigated using matrix-assisted laser desorption ionization (MALDI) mass spectrometry imaging (MSI). The LC-Q-TOF analysis revealed the distribution of micropollutants in three different compartments of a tertiary treatment wetland. When further investing the metabolic profile of S. alba leaves using MSI, different distribution patterns were observed in specific leaf tissues. Xenobiotic metabolites were predicted and could also be tentatively identified in S. alba leaves, shedding new light on the metabolic processes at play in leaves to manage xenobiotics uptake from a polluted environment. Using complementary metabolomics approaches, this study performed a large-scale exploration of micropollutants spreading in the environment at the exit of a tertiary treatment wetland. The use of MSI coupled with the prediction of xenobiotic metabolites yielded novel insights into plant metabolism during chronical exposure to low doses of a mixture of micropollutants.

Plants are able to sense a rise in temperature of several degrees, and appropriately adapt their metabolic and growth processes. To this end, plants produce various signalling molecules that act throughout the plant body. Here, we report that root-derived GA

Barley (Hordeum vulgare) is the fourth crop cultivated in the world for human consumption and animal feed, making it important to breed healthy and productive plants. Among the threats for barley are lodging, diseases, and pathogens. To avoid lodging, dwarf and semi-dwarf mutants have been selected through breeding processes. Most of these mutants are affected on hormonal biosynthesis or signalling. Here, we present the metabolic characterization of a brassinosteroid insensitive semi-dwarf mutant, BW312. The hormone profile was determined through a targeted metabolomics analysis by UHPLC-triple quadrupole-MS/MS, showing an induction of gibberellic acid and jasmonic acid in the semi-dwarf mutant. A non-targeted metabolomics analysis by UHPLC-QTOF-MS/MS revealed a differential metabolic profile, with 16 and 9 metabolites showing higher intensities in the mutant and wild-type plants respectively. Among these metabolites, azelaic acid was identified. Gibberellic acid, jasmonic acid, and azelaic acid are involved in pathogen resistance, showing that this semi-dwarf line has an enhanced basal pathogen resistance in absence of pathogens, and therefore is of interest in breeding programs to fight against lodging, but also probably to increase pathogen resistance.

Vitamin D3 is a secosterol hormone critical for bone growth and calcium homeostasis, produced in vertebrate skin by photolytic conversion of the cholesterol biosynthetic intermediate provitamin D3. Insufficient levels of vitamin D3 especially in the case of low solar UV-B irradiation is often compensated by an intake of a dietary source of vitamin D3 of animal origin. Small amounts of vitamin D3 were described in a few plant species and considered as a peculiar feature of their phytochemical diversity. In this report we show the presence of vitamin D5 in the model plant Arabidopsis thaliana. This plant secosterol is a UV-B mediated derivative of provitamin D5, the precursor of sitosterol. The present work will allow a further survey of vitamin D distribution in plant species.

Phytosterols are classified into C24-ethylsterols and C24-methylsterols according to the different C24-alkylation levels conferred by two types of sterol methyltransferases (SMTs). The first type of SMT (SMT1) is widely conserved, whereas the second type (SMT2) has diverged in charophytes and land plants. The Arabidopsis smt2 smt3 mutant is defective in the SMT2 step, leading to deficiency in C24-ethylsterols while the C24-methylsterol pathway is unchanged. smt2 smt3 plants exhibit severe dwarfism and abnormal development throughout their life cycle, with irregular cell division followed by collapsed cell files. Preprophase bands are occasionally formed in perpendicular directions in adjacent cells, and abnormal phragmoplasts with mislocalized KNOLLE syntaxin and tubulin are observed. Defects in auxin-dependent processes are exemplified by mislocalizations of the PIN2 auxin efflux carrier due to disrupted cell division and failure to distribute PIN2 asymmetrically after cytokinesis. Although endocytosis of PIN2-GFP from the plasma membrane (PM) is apparently unaffected in smt2 smt3, strong inhibition of the endocytic recycling is associated with a remarkable reduction in the level of PIN2-GFP on the PM. Aberrant localization of the cytoplasmic linker associated protein (CLASP) and microtubules is implicated in the disrupted endocytic recycling in smt2 smt3. Exogenous C24-ethylsterols partially recover lateral root development and auxin distribution in smt2 smt3 roots. These results indicate that C24-ethylsterols play a crucial role in division plane determination, directional auxin transport, and polar growth. It is proposed that the divergence of SMT2 genes together with the ability to produce C24-ethylsterols were critical events to achieve polarized growth in the plant lineage.

Vitamin D3 is a secosterol hormone critical for bone growth and calcium homeostasis, produced in vertebrate skin by photolytic conversion of the cholesterol biosynthetic intermediate provitamin D3. Insufficient levels of vitamin D3 especially in the case of low solar UV-B irradiation is often compensated by an intake of a dietary source of vitamin D3 of animal origin. Small amounts of vitamin D3 were described in a few plant species and considered as a peculiar feature of their phytochemical diversity. In this report we show the presence of vitamin D5 in the model plant Arabidopsis thaliana. This plant secosterol is a UV-B mediated derivative of provitamin D5, the precursor of sitosterol. The present work will allow a further survey of vitamin D distribution in plant species.

The presence of human drugs in the aquatic environment is partly due to an incomplete and insufficient removal process of wastewater treatment plants (WWTPs). Thus, drug traces are observed at different concentrations in water bodies, sediments and aquatic plants all over the world. At the same time, Surface Flow Treatment Wetlands (SFTWs) at the outlet of WWTPs are commonly observed in small municipalities as complementary treatment. However, little is known regarding the role of SFTWs in the complementary mitigation of emerging contaminants, such as drugs, and the interactions between drugs, plants and sediment throughout the seasons. For that reason, we conducted sampling sessions over a period of two years on a full-scale SFTW downstream of a vertical-flow constructed wetland. At each session, the SFTW influent and effluent, as well as five different plant species and one composite sediment sample, were sampled. We detected more than fifty pharmaceutical compounds in the inflow and outflow water. The compounds most frequently detected were bisoprolol and ketoprofen. We emphasized that the SFTW removal ability was better in the summer than in the winter, due to the impact of weather on physicochemical parameters. Large variations of removal efficiencies were also observed when considering all of the detected compounds. Large seasonal variations were also observed for each compound. In addition, the study of the five plants showed their ability to uptake drugs from water and soil to the leaves in a species-specific manner. The pharmaceutical composition of the sediment was also correlated with the season: the maximum occurrence was reached in summer, and the minimum was reached in winter. Finally, the continuous decrease in removal efficiencies highlights the ageing effect on SFTW removal ability.

In eukaryotes, DNA repair pathways help to maintain genome integrity and epigenomic patterns. However, the factors at the nexus of DNA repair and chromatin modification/remodeling remain poorly characterized. Here, we uncover a previously unrecognized interplay between the DNA repair factor DNA DAMAGE BINDING PROTEIN2 (DDB2) and the DNA methylation machinery in Arabidopsis thaliana. Loss-of-function mutation in DDB2 leads to genome-wide DNA methylation alterations. Genetic and biochemical evidence indicate that at many repeat loci, DDB2 influences de novo DNA methylation by interacting with ARGONAUTE4 and by controlling the local abundance of 24-nucleotide short interfering RNAs (siRNAs). We also show that DDB2 regulates active DNA demethylation mediated by REPRESSOR OF SILENCING1 and DEMETER LIKE3. Together, these findings reveal a role for the DNA repair factor DDB2 in shaping the Arabidopsis DNA methylation landscape in the absence of applied genotoxic stress.

Fragile X syndrome (FXS) is caused by the absence of the Fragile X Mental Retardation Protein (FMRP) in neurons. In the mouse, the lack of FMRP is associated with an excessive translation of hundreds of neuronal proteins, notably including postsynaptic proteins. This local protein synthesis deregulation is proposed to underlie the observed defects of glutamatergic synapse maturation and function and to affect preferentially the hundreds of mRNA species that were reported to bind to FMRP. How FMRP impacts synaptic protein translation and which mRNAs are most important for the pathology remain unclear. Here we show by cross-linking immunoprecipitation in cortical neurons that FMRP is mostly associated with one unique mRNA: diacylglycerol kinase kappa (Dgkκ), a master regulator that controls the switch between diacylglycerol and phosphatidic acid signaling pathways. The absence of FMRP in neurons abolishes group 1 metabotropic glutamate receptor-dependent DGK activity combined with a loss of Dgkκ expression. The reduction of Dgkκ in neurons is sufficient to cause dendritic spine abnormalities, synaptic plasticity alterations, and behavior disorders similar to those observed in the FXS mouse model. Overexpression of Dgkκ in neurons is able to rescue the dendritic spine defects of the Fragile X Mental Retardation 1 gene KO neurons. Together, these data suggest that Dgkκ deregulation contributes to FXS pathology and support a model where FMRP, by controlling the translation of Dgkκ, indirectly controls synaptic proteins translation and membrane properties by impacting lipid signaling in dendritic spine.

Patterned hair loss (PHL) affects around 50% of the adult population worldwide. The negative impact that this condition exerts on people’s life quality has boosted the appearance of over-the-counter products endowed with hair-promoting activity. Nutraceuticals enriched in polyphenols have been recently shown to promote hair growth and counteract PHL. Malus pumila Miller cv. Annurca is an apple native to Southern Italy presenting one of the highest contents of Procyanidin B2. We have recently shown that oral consumption of Annurca polyphenolic extracts (AAE) stimulates hair growth, hair number, hair weight and keratin content in healthy human subjects. Despite its activity, the analysis of the molecular mechanism behind its hair promoting effect is still partially unclear. In this work we performed an unprecedented metabolite analysis of hair follicles (HFs) in mice topically treated with AAE. The metabolomic profile, based on a high-resolution mass spectrometry approach, revealed that AAE re-programs murine HF metabolism. AAE acts by inhibiting several NADPH dependent reactions. Glutaminolysis, pentose phosphate pathway, glutathione, citrulline and nucleotide synthesis are all halted in vivo by the treatment of HFs with AAE. On the contrary, mitochondrial respiration, β-oxidation and keratin production are stimulated by the treatment with AAE. The metabolic shift induced by AAE spares amino acids from being oxidized, ultimately keeping them available for keratin biosynthesis.

The specific metabolic profile of aqueous extracts of caviar samples (n = 91) originating from producers in the Aquitaine region in France was determined using 1H NMR spectroscopy. This metabolic profile was used to develop multivariate statistical models (Soft Independent Modeling by Class Analogy (SIMCA) and Orthogonal Partial Least Square Discriminant Analysis (OPLS-DA)) for the purpose of differentiating the Aquitaine production from other productions. The main purpose of these models is to help Aquitaine producers establish a protected geographical indication (PGI) to protect their know-how in caviar production from aquaculture. The parameters characterizing both the OPLS-DA and the SIMCA models were quite satisfactory, and the analysis of blind test samples with the two models provided a good level of discrimination between Aquitaine caviars and other caviars. The same NMR metabolic profile could also be used to provide an estimation of the freshness of caviar samples and define a shelf life for caviar cans. The first characterization of the different metabolites detected in caviar specimens by 1H NMR spectroscopy is also presented. The statistical models obtained could be used to prevent counterfeiting of Aquitaine caviar and guarantee an adequate level of freshness.

The gibberellin (GA) phytohormones play important roles in plant growth and development, promoting seed germination, elongation growth and reproductive development(1). Over the years, substantial progress has been made in understanding the regulation of GA signalling and metabolism, which ensures appropriate levels of GAs for growth and development(2). Moreover, an additional level of regulation may reside in the transport of GAs from production sites to recipient tissues that require GAs for growth. Although there is considerable evidence suggesting the existence of short- and long-distance movement of GAs in plants(3-8), the nature and the biological properties of this transport are not yet understood. Here, we combine biochemical and conventional micrografting experiments in Arabidopsis thaliana to show that the GA precursor GA12, although biologically inactive by itself, is the major mobile GA signal over long distances. Quantitative analysis of endogenous GAs in xylem and phloem exudates further indicates that GA12 moves through the plant vascular system. Finally, we demonstrate that GA12 is functional in recipient tissues, supporting growth via the activation of the GA signalling cascade. Collectively, these results reveal the existence of long-range transport of endogenous GA12 in plants that may have implications for the control of developmental phase transitions and the adaptation to adverse environments.

The effect of an inhibitor of cycloartenol synthase (CAS, EC 5.4.99.8) on the proteome of tobacco BY-2 cells has been examined. CAS catalyzes the first committed step in phytosterol synthesis in plants. BY-2 cells were treated with RO 48-8071, a potent inhibitor of oxidosqualene cyclization. Proteins were separated by two-dimensional electrophoresis and spots, that clearly looked differentially accumulated after visual inspection, were cut, in-gel trypsin digested, and peptides were analyzed by nano-HPLC–MS/MS. Distinct peptides were compared to sequences in the data banks and attributed to corresponding proteins and genes. Inhibition of CAS induced proteins that appear to mitigate the negative effects of the chemical exposure. However, as all enzymes that are directly involved in phytosterol biosynthesis are low-abundant proteins, significant changes in their levels could not be observed. Differences could be seen with enzymes involved in primary metabolism (glycolysis, pentose phosphate pathway etc.), in proteins of the chaperonin family, and those, like actin, that participate in formation and strengthening of the cytoskeleton and have some impact on cell growth and division.

Constructed wetland are popular systems used to treat wastewater in rural areas in France. But these systems are facing to the micropollutants issues. This study aims to understand the micropollutants distribution in the wetland ecosystems. Therefore, micropollutants, lipids and plants large scale screening were performed in the wetland ecosystem, as well as in the different sludge layers from the constructed wetland. Nevertheless, the spatial distribution should also be investigated inside the organisms to understand the bioprocesses. The storage and degradation mechanisms to deal with micropollutants has been unveiled using mass spectrometry imaging. Nonetheless, water remains the key vector of micropollutants in the organisms or in the environment. The water distribution should in this way be investigated to explore the micropollutants distribution. Therefore, hydraulics numerical modelling was combined with micropollutants large scale screening to investigate their distribution.; Les filtres plantés de roseaux, filière de traitement privilégiée en France pour traiter les eaux usées en milieu rural, fait face à la problématique des micropolluants. L’étude menée vise à comprendre la distribution et le devenir d’un large spectre de micropolluants dans l’écosystème de ces filières extensives. Pour cela, le profil des micropolluants et du métabolome au sein des différents compartiments (eau, boues, plantes) a été établi par une analyse LC-MS/MS en spectre large. D’autre part pour évaluer, l’infiltration de ces polluants un profil métabolique a été décrit sur la profondeur des boues des filtres plantés. Mais cette distribution spatiale peut également être obtenue à l’échelle de l’organisme afin de comprendre certains bioprocédés. L’utilisation de l’imagerie par spectrométrie de masse a pu mettre en évidence ces localisations et les mécanismes mise en œuvre par les plantes pour faire face à ces polluants. Enfin l’eau demeure le principal vecteur des micropolluants dans l’environnement. Ainsi les données de micropolluants ont été couplées à une modélisation numérique d’écoulement pour comprendre leur distribution au sein de ces systèmes.

Isoprenoids are a large class of molecules found in all living organisms that are implicated in diverse biological processes. The aim of my thesis was to decipher if they could be involved in the interactions between plants and bacteria. Therefore, I worked on Arabidopsis thaliana wild-type and mutants, altered in the two isoprenoid biosynthesis pathways occurring in higher plants. An inventory of the communities interacting with wild-type and mutants highlighted some differentially abundant bacteria, despite the existence of a core microbiota. In addition, plants affected in the plastidial biosynthesis pathway, referred as the methylerythritol phosphate (MEP) pathway, have been shown to be more affected than wild-type by Pseudomonas syringae, a well-known phytopathogen. Together, these results suggest that isoprenoids may play a role in the interactions between plants and bacteria. In addition, 230 strains were isolated from A. thaliana in the laboratory, among which some of them were tested for their impact on the plant fitness and resistance to P. syringae, and for the impact on isoprenoids on these strains.; Les isoprénoïdes constituent une grande classe de molécules que l'on retrouve chez tous les organismes vivants et qui sont impliquées dans divers processus biologiques. Le but de ma thèse était de déterminer si ces molécules pouvaient être impliquées dans les interactions entre plantes et bactéries. J'ai travaillé sur des plantes Arabidopsis thaliana sauvages, et sur deux mutants affectés dans chacune des deux voies de biosynthèse des isoprénoïdes existant chez les plantes supérieures. Un inventaire des communautés constituant le microbiote de ces plantes a mis en évidence certaines bactéries dont l’abondance varie dépendamment du génotype, malgré l'existence d'un microbiote commun entre plantes sauvages et mutantes. De plus, il a été démontré que les plantes affectées dans la voie de biosynthèse plastidiale, dite du méthylérythritol phosphate (MEP), sont plus sensibles que les plantes sauvages à l’infection par Pseudomonas syringae, un phytopathogène bien connu. Ensemble, ces résultats suggèrent que les isoprénoïdes peuvent jouer un rôle dans les interactions entre plantes et bactéries. D’autre part, 230 souches interagissant avec A. thaliana ont été isolées au laboratoire, parmi lesquelles certaines ont été testées pour déterminer leur effet sur le phénotype et la résistance des plantes à P. syringae, ainsi que l’effet des isoprénoïdes sur ces souches.