Biology subjects

Bartoli, C.

Publications and source records attributed to Bartoli, C..

12 recordsLinked to original sources

bioRxiv2026

Natural habitats are reservoirs of Fusarium lineages highly pathogenic on Triticum aestivum

Fungal plant diseases are a major cause of crop loss worldwide. Understanding the processes driving these diseases is therefore crucial to anticipate and control epidemics while improving crop yield production. Moreover, the new European Green Deal aims to reduce the use of pesticides, while, few alternatives are currently available on the market. There is therefore an urgent need to better track and anticipate fungal crop epidemics in the current context of fungicide reduction. In light of this, our study aims to understand Fusarium spill overs from non-agricultural habitats in order to better characterise potential non-host Fusarium reservoirs that may be implicated in the emergence of Fusarium diseases. To address this question, we isolated Fusarium lineages from natural populations of Brassica rapa. We characterised their phylogenomic affiliation and found that they display high diversity, with a population structure related to the locality of isolation. By inoculation assays, we identified Fusarium strains from non-agricultural habitats that were highly aggressive on wheat. In addition, we observed a strong effect of wheat variety on disease development. We monitored the Fusarium colonisation through a microscopy approach in both wheat and Brassica plants. We observed that while the fungus is mostly on root surface in Brassica plants, it spreads inter-cellularly in wheat roots with vascular colonisation in the wheat shoots. Finally, we showed that most aggressive Fusarium strains were isolated from Brittany, a French region where wheat is vastly cultivated.

ecology↗

bioRxiv2026

AZD5069 Inhibits Angiogenesis Without Cytotoxicity In Human Endothelial Cell Culture

BackgroundThe CXCR2 receptor pathway plays a major role in inflammatory and invasive angiogenesis in human disease. ObjectiveWe evaluated AZD5069, a selective CXCR2 antagonist, as an angiogenesis inhibitor in human cell culture. MethodsHuman Umbilical Venous Endothelial Cells (HUVECs), Human Aortic Endothelial Cells (HAECs), and Human Pulmonary Artery Endothelial Cells (HPAECs) were cultured with standard in vitro techniques. AZD5069 (0, 8, 16, 32, 64, 128, 256 M) was evaluated as an angiogenesis inhibitor with fluorescent-labeled 5-Ethynyl-2-deoxyuridine (EdU) uptake to quantify endothelial cell proliferation, scratch assay to quantify endothelial cell migration, and Geltrex assay to quantify endothelial cell tubule and hub formation. AZD5069 cytotoxicity was evaluated with in situ terminal deoxynucleotidyl transferase 2-Deoxyuridine triphosphate- 5 (dUTP) nick-end labeling (TUNEL) to quantify apoptosis and membrane-impermeable cyanine dye uptake to quantify necrotic cell death. ResultsAZD5069 significantly reduced HUVEC, HAEC, and HPAEC proliferation, migration, tubule count, total tubule length, and node count with a dose-response. AZD5069 did not cause apoptosis nor necrotic cell death. ConclusionsAZD5069 inhibited angiogenesis without cytotoxicity in human endothelial cell culture. The endothelial cell CXCR2 receptor pathway may be a novel target for anti-angiogenesis therapy. AZD5069 may have clinical utility in cardiovascular, oncologic, and inflammatory disease. Condensed AbstractThe CXCR2 receptor pathway plays a major role regulating angiogenesis in inflammation and cancer. The CXCR2 receptor pathway has been evaluated in humans as a target for therapy in inflammatory disease and cancer but not as a therapeutic approach to block pathologic angiogenesis. AZD5069 is a clinical stage, direct CXCR2 antagonist. In human endothelial cell culture, AZD5069 inhibited angiogenesis without causing apoptosis or necrotic cell death. The endothelial cell CXCR2 receptor pathway may be a novel target for anti-angiogenesis therapy. AZD5069 may have clinical utility as a novel angiogenesis blocker in human disease. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=137 SRC="FIGDIR/small/731993v1_ufig1.gif" ALT="Figure 1"> View larger version (22K): org.highwire.dtl.DTLVardef@1b0bd3forg.highwire.dtl.DTLVardef@58ad69org.highwire.dtl.DTLVardef@1e0cdcdorg.highwire.dtl.DTLVardef@1e7708b_HPS_FORMAT_FIGEXP M_FIG Visual Abstract: AZD5069, a selective CXCR2 antagonist, significantly reduced endothelial cell proliferation, migration, and vascular tubule formation without causing necrotic or apoptotic cell death. The endothelial cell CXCR2 receptor pathway may be a novel target for anti-angiogenesis therapy. AZD5069 may have clinical utility in human cardiovascular, oncologic, and inflammatory disease with pathologic, dysregulated, or excessive angiogenesis. C_FIG

pharmacology and toxicology↗

bioRxiv2023

Plant genetic bases explaining microbiota diversity shed light into a novel holobiont generalist gene theory

Plants as animals are strictly associated with a cortege of microbial communities influencing their health, fitness and evolution. Therefore, scientists refer to all living organisms as holobionts; complex genetic units that coevolve simultaneously. This is what has been recently proposed as the hologenome theory of evolution. This exciting and attractive theory has important implications on animal and plant health; however, it still needs consistent proof to be validated. Indeed, holobionts are still poorly studied in their natural habitats where coevolution and natural selective processes occur. Compared to animals and crops, wild plant populations are an excellent and unique model to explore the hologenome theory. These sessile holobionts have strictly coevolved with their microbiota for decades and natural selection and adaptive processes acting on wild plants are likely to regulate the plant-microbe interactions. Here we conducted for the first time a microbiota survey, plant genome sequencing and Genome-Environmental Analysis (GEA) of 26 natural populations of the non-model plant species Brassica rapa. We collected plants over two seasons in Italy and France, and analyzed the microbiota on two plant compartments (root and rhizosphere). We identified that plant compartment and season modulate B. rapa microbiota. More importantly, when conducting GEA we evidenced neat peaks of association correlating with both fungal and bacterial microbiota. Surprisingly, we found 13 common genes between fungal and bacterial diversity descriptors that we referred under the name of Holobiont Generalist Genes (HGG). These genes might strongly regulate the diversity and composition of plant microbiota at the inter-kingdom level. Significance StatementThe novel hologenome concept claims that hosts and their associated microbes (considered as holobionts) are a unique evolutionary unit on which natural selection acts. Thus, the hologenome theory assumes that hosts and microbiomes simultaneously coevolve. This novel vision of universal evolutionary entities is promising for both animal and plant health purposes. However, it is still quietly controversial as it suffers from a lack of tangible evidence. How can we enrich the debate on holobionts? How can we translate this concept in discoveries that can change farming practices? Our study is filling the gaps of the hologenome theory by showing that certain genes under natural selection and regulating plant microbiota are generalist in response to fungal and bacterial communities.

evolutionary biology↗

bioRxiv2023

Warnings/Cautions when collecting Brassica diversity along a large climatic gradient

Agriculture faces great challenges to overcome global warming and to improve system sustainability, requiring access to novel genetic diversity. So far, wild populations and local landraces remain poorly explored. This is notably the case for the two diploid species, Brassica oleracea L. (CC, 2n=2x=18) and B. rapa L. (AA, 2n=2x=20). In order to explore genetic diversity in both species, we have collected numerous populations in their center of origin, the Mediterranean basin, on a large contrasting climatic and soil gradient from northern Europe to southern sub-Saharan regions. In these areas, we also collected 14 populations belonging to five B. oleracea closely related species. Before further genetic and agronomic investigations, we controlled the absence of species misidentification using flow cytometry, sequencing of species specific chloroplast genomic region, as well as cytogenetic analyses in case of unexpected results. Looking at the 102 B. oleracea and 146 B. rapa populations showing a good germination among the 112 and 154 populations collected, seventeen populations were misidentified. The most frequent mistake was a confusion of these diploid species with B. napus. Additionally for B. rapa, 2 autotetraploid populations were observed. Habitats of the collected wild populations and landraces are described in our work. This provides a unique plant material characterization that will pave the way for further analyses investigating the genomic regions involved in climatic and microbiota adaptation. This research is supported by the H2020 Prima project BrasExplor.

ecology↗

bioRxiv2022

The genetic architecture of adaptation to leaf and root bacterial microbiota in Arabidopsis thaliana

Understanding the role of host genome in modulating microbiota variation is a need to shed light into the holobiont theory and overcome the current limits on the description of host-microbiota interactions at the genomic and molecular levels. However, the host genetic architecture structuring microbiota is only partly described in plants. In addition, most association genetic studies on microbiota are often carried out outside the native habitats where the host evolve and the identification of signatures of local adaptation on the candidate genes has been overlooked. To fill these gaps and dissect the genetic architecture driving adaptive plant-microbiota interactions, we adopted a Genome-Environmental-Association (GEA) analysis on 141 whole-genome sequenced natural populations of Arabidopsis thaliana characterized in situ for their leaf and root bacterial communities and a large range of environmental descriptors (i.e. climate, soil and plant communities). Across 194 microbiota traits, a much higher fraction of among-population variance was explained by the host genetics than by ecology, with the plant neighborhood as the main ecological driver of microbiota variation. Importantly, the relative importance of host genetics and ecology expressed a phylogenetic signal at the family and genus level. In addition, the polygenic architecture of adaptation to bacterial communities was highly flexible between plant compartments and seasons. Relatedly, signatures of local adaptation were stronger on QTLs of the root microbiota in spring. Finally, we provide evidence that plant immunity, in particular the FLS2 gene, is a major source of adaptive genetic variation structuring bacterial assemblages in A. thaliana.

microbiology↗

bioRxiv2022

Unraveling the genetic architecture of the adaptive potential of Arabidopsis thaliana to face the bacterial pathogen Pseudomonas syringae in the context of global change

Phytopathogens are a continuous threat for global food production and security. Emergence or re-emergence of plant pathogens is highly dependent on the environmental conditions affecting pathogen spread and survival. Under climate change, a geographic expansion of pathogen distribution poleward has been observed, potentially resulting in disease outbreaks on crops and wild plants. Therefore, estimating the adaptive potential of plants to novel epidemics and describing its underlying genetic architecture, is a primary need to propose agricultural management strategies reducing pathogen outbreaks and to breed novel plant cultivars adapted to pathogens that might spread in novel habitats under climate change. To address this challenge, we inoculated Pseudomonas syringae strains isolated from Arabidopsis thaliana populations located in south-west of France on the highly genetically polymorphic TOU-A A. thaliana population located east-central France. While no adaptive potential was identified in response to most P. syringae strains, the TOU-A population displays a variable disease response to the P. syringae strain JACO-CL belonging to the phylogroup 7 (PG7). This strain carried a reduced T3SS characteristic of the PG7 as well as flexible genomic traits and potential novel effectors. GWA mapping on 192 TOU-A accessions inoculated with JACO-CL revealed a polygenic architecture. The main QTL region encompasses two R genes and the AT5G18310 gene encoding for ubiquitin hydrolase, a target of the AvrRpt2 P. syringae effector. Altogether, our results pave the way for a better understanding of the genetic and molecular basis of the adaptive potential in an ecologically relevant A. thaliana - P. syringae pathosystem.

pathology↗

bioRxiv2022

Rhizocarpon geographicum lichen discloses a highly diversified microbiota carrying antibiotic resistance and Persistent Organic Pollutants tolerance

As rock-inhabitants, lichens are exposed to extreme and fluctuating abiotic conditions associated with poor sources of nutriments. These extreme conditions confer to lichens the unique ability to develop protective mechanisms. Consequently, lichen-associated microbes disclose highly versatile lifestyles and ecological plasticity, enabling them to withstand extreme environments. Because of their ability to grow on poor and extreme habitats, bacteria associated with lichens can tolerate a wide range of pollutants and on the other hand secrete antimicrobial compounds. In addition, lichen-associated bacteria were described to harbor ecological functions crucial for the evolution of the lichen holobiont. Nevertheless, the ecological features of lichen-associated microbes are still underestimated. To explore the untapped ecological diversity of lichen-associated bacteria, we adopted a novel culturomic approach on the crustose lichen Rhizocarpon geographicum. We sampled R. geographicum in French habitats exposed to oil spill and we combined 9 culturing methods with 16S rRNA sequencing to capture the largest bacterial diversity. A deep functional analysis of the lichen-associated bacterial collection showed the presence of a set of bacterial strains resistant to a wide range of antibiotics and displaying tolerance to Persistent Organic Pollutants (POP). Our study is a starting point to explore the ecological features of the lichen microbiota.

microbiology↗

bioRxiv2022

Investigating genetic diversity within the most abundant and prevalent non-pathogenic leaf-associated bacteria interacting with Arabidopsis thaliana in natural habitats

Plants interact simultaneously with highly diversified microbes defined as the plant microbiota. Microbiota modulates plant health and appears as a promising lever to develop innovative, sustainable and eco-friendly agro-ecosystems. Key patterns of microbiota assemblages in plants have been revealed by an extensive number of studies based on taxonomic profiling by metabarcoding. However, understanding the functionality of microbiota and identifying the genetic and molecular mechanisms underlying the interplay between plants and their microbiota are still in its infancy and relies on reductionist approaches primarily based on the establishment of representative microbial collections. In Arabidopsis thaliana, most of these microbial collections include one strain per OTU isolated from a limited number of habitats, thereby neglecting the ecological potential of genetic diversity within microbial species to affect the plant-microbiota molecular dialog. With this study, we aimed at estimating the extent of genetic variation between strains within the most abundant and prevalent leaf-associated non-pathogenic bacterial species in 163 natural populations of A. thaliana located south-west of France. By combining a culture-based collection approach consisting of the isolation of more than 7,000 bacterial colonies with an informative-driven approach, we isolated 35 pure strains from eight non-pathogenic bacterial species. We detected significant intra-specific genetic variation at the genomic level and for growth rate in synthetic media. In addition, significant host genetic variation was detected in response to most bacterial strains in in vitro conditions, with the presence of both negative and positive responses on plant growth. Our study provides new genetic and genomic resources for a better understanding of the plant-microbe ecological interactions at the microbiota level. We also highlight the need of considering genetic variation in both non-pathogenic bacterial species and A. thaliana to decipher the genetic and molecular mechanisms involved in the ecologically relevant dialog between hosts and leaf microbiota.

microbiology↗

bioRxiv2020

Rhizobium leguminosarum symbiovar viciae strains are natural wheat endophytes and can stimulate root development and colonization by arbuscular mycorrhizal fungi

O_LIAlthough rhizobia establishing a nitrogen-fixing symbiosis with legumes are also known to promote growth in non-legumes, studies on rhizobia association with wheat roots are scarce. C_LIO_LIWe searched for Rhizobium leguminosarum symbiovar viciae (Rlv) strains naturally competent for wheat roots colonization. We isolated 20 strains and tested the ability of a subset for wheat roots colonization when co-inoculated with other Rlv. We also measured the effect of these strains on wheat root architecture and Arbuscular Mycorrhizal Fungal (AMF) colonization. C_LIO_LIWe found a low diversity of Rlv in wheat roots compared to that observed in the Rlv species complex. Only a few strains, including those isolated from wheat roots, and one strain isolated from pea nodules, were efficient to colonize wheat roots in co-inoculation conditions. These strains had a high ability for endophytic colonization of wheat root and were able to stimulate root development and AMF colonization in single strain inoculation conditions. C_LIO_LIThese results suggest that wheat is an alternative host for some Rlv; nevertheless, there is a strong competition between Rlv strains for wheat root colonization. Furthermore, our study suggests that the level of endophytic colonization is critical for Rlv ability to promote wheat growth. C_LI

microbiology↗

bioRxiv2019

Heat stress induces ferroptosis in a photosynthetic prokaryote.

Ferroptosis is an oxidative iron-dependent form of cell death recently described in eukaryotic organisms like animals, plants and parasites. Here we report that a similar process takes place in the cyanobacterium Synechocystis sp. PCC 6803 in response to heat stress. After a heat shock, Synechocystis cells undergo a cell death pathway that can be suppressed by canonical ferroptosis inhibitors or by external addition of calcium, glutathione or ascorbic acid. Moreover, as described for eukaryotic cells ferroptosis, this pathway is characterized by an early depletion of antioxidants, and by lipid peroxidation. As in general prokaryotes membranes contain poorly oxidizable saturated or monounsaturated lipid molecules, it was thought that they were not susceptible to ferroptosis. Interestingly, cyanobacteria contain thylakoid membranes that are enriched in polyunsaturated-fatty-acid-containing phospholipids, which might explain their sensitivity to ferroptosis. These results indicate that all of the hallmarks described for eukaryotic ferroptosis are conserved in photosynthetic prokaryotes and suggest that ferroptosis might be an ancient cell death program.\n\nSummaryAguilera et al, show that ferroptosis, an oxidative and iron-dependent form of regulated cell death, plays an important role in the cyanobacterium Synechocystis sp. PCC 6803 in response to heat stress.

microbiology↗

bioRxiv2018

In situ relationships between microbiota and potential pathobiota in Arabidopsis thaliana

A current challenge in microbial pathogenesis is to identify biological control agents that may prevent and/or limit host invasion by microbial pathogens. In natura, hosts are often infected by multiple pathogens. However, most of the current studies have been performed under laboratory controlled conditions and by taking into account the interaction between a single commensal species and a single pathogenic species. The next step is therefore to explore the relationships between host-microbial communities (microbiota) and microbial members with potential pathogenic behavior (pathobiota) in a realistic ecological context. In the present study, we investigated such relationships within root and leaf associated bacterial communities of 163 ecologically contrasted Arabidopsis thaliana populations sampled across two seasons in South-West of France. In agreement with the theory of the invasion paradox, we observed a significant humped-back relationship between microbiota and pathobiota -diversity that was robust between both seasons and plant organs. In most populations, we also observed a strong dynamics of microbiota composition between seasons. Accordingly, the potential pathobiota composition was explained by combinations of season-specific microbiota OTUs. This result suggests that the potential biomarkers controlling pathogens invasion are highly dynamic.

microbiology↗

bioRxiv2017

Genetic variants affecting plant size and chemical defenses jointly shape herbivory in Arabidopsis

Herbivorous insects exhibit strong feeding preferences when choosing among plant genotypes, yet experiments to map loci mediating plant susceptibility to herbivory rarely incorporate host choice. To address this gap, we applied genome-wide association (GWA) mapping to uncover genetic polymorphisms mediating damage from foraging insects (two populations of Scaptomyza flava) across a mixture of Arabidopsis thaliana genotypes in experimental enclosures. The effect of chemical defenses (glucosinolates) on herbivory depended on herbivore genotype. Unlike many studies that minimize the effects of host choice behavior, we also found a large effect of plant size on herbivory--likely through its effect on plant apparency--that was independent of herbivore genotype. These herbivory-associated loci are polymorphic at fine spatial scales, and thus have potential to shape variation in herbivory within natural populations. We also show that the polymorphism with the largest effect on herbivory underlies adaptive latitudinal variation in Arabidopsis plant size across Europe. Overall, our results provide genetic support for ecological observations that variation in both chemical defenses and non-canonical defense traits (e.g., plant size and phenology) jointly shapes plant-herbivore interactions.

plant biology↗