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

ABSTRACT 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

Cell-Based Antioxidant Properties and Synergistic Effects of Natural Plant and Algal Extracts Pre and Post Intestinal Barrier Transport

In this work, both direct and indirect cell-based antioxidant profiles were established for 27 plant extracts and 1 algal extract. To evaluate the direct antioxidant effects, fluorescent AOP1 cell assay was utilized, which measures the ability of different samples to neutralize intracellular free radicals produced by a cell-based photo-induction process. As the intestinal barrier is the first cell line crossed by the product, dose response curves obtained from Caco-2 cells were used to establish EC50 values for 26 out of the 28 natural extracts. Among them, 11 extracts from Vitis, Hamamelis, Syzygium, Helichrysum, Ilex and Ribes genera showed remarkable EC50s in the range of 10 µg/mL. In addition to this, a synergistic effect was found when combinations of the most potent extracts (S. aromaticum, H. italicum, H. virginiana, V. vinifera) were utilized compared to extracts alone. Indirect antioxidant activities (i.e., the ability of cells to trigger antioxidant defenses) were studied using the ARE/Nrf2 luminescence reporter-gene assay in HepG2 cells, as liver is the first organ crossed by an edible ingredient once it enters in the bloodstream. Twelve extracts were subjected to an intestinal epithelial barrier passage in order to partially mimic intestinal absorption and show whether basolateral compartments could maintain direct or indirect antioxidant properties. Using postepithelial barrier samples and HepG2 cells as a target model, we demonstrate that indirect antioxidant activities are maintained for three extracts, S. aromaticum, H. virginiana and H. italicum. Our experimental work also confirms the synergistic effects of combinations of post-intestinal barrier compartments issued from apical treatment with these three extracts. By combining cell-based assays together with an intestinal absorption process, this study demonstrates the power of cell systems to address the issue of antioxidant effects in humans

The genetic architecture of the adaptive potential of Arabidopsis thaliana in response to Pseudomonas syringae strains isolated from south-west France

International audiencePhytopathogens are a 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 the 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 under climate change. To address this challenge, we inoculated Pseudomonas syringae strains isolated from Arabidopsis thaliana populations from south-west of France on the highly genetically polymorphic TOU-A A. thaliana population from north-east France. While no adaptive potential was identified in response to most P. syringae strains, the TOU-A population displayed a variable disease response to the JACO-CL strain belonging to the P. syringae phylogroup 7 (PG7). This strain carried a reduced type III secretion system (T3SS) characteristic of the PG7 as well as flexible genomic traits and potential novel effectors. Genome-wide association mapping on 192 TOU-A accessions revealed a polygenic architecture of disease response to JACO-CL. The main quantitative trait locus (QTL) region encompasses two R genes and the AT5G18310 gene encoding 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

The French pill scare and the reshaping of social inequalities in access to medical contraceptives

While the consequences of various "pill scares" have been relatively well-documented in the public health literature revealing a drop in pill use and a rise in unplanned pregnancies and abortion rates, researchers rarely considered that these controversies would affect women contraceptive practices differently according to their social background. Indeed, social differentiations in reaction to "pill scares" could contribute to reinforce the social gradient in the use of contraceptive methods and choice of visiting the health professionals who prescribe them. These could contribute to an increase in health inequalities on access to contraceptive methods. Using data from three state nationally representative cross-sectional surveys conducted in France in 2010, 2013 and 2016, we studied the changes in women's contraceptive uses around the French "pill scare" that occurred in 2012–2013. We focused on the changes in the use of all contraceptives available under medical prescription (called medical contraceptives) on one hand, and on each specific method (pill, IUD, implant, patch or vaginal ring, and female sterilization) on the other hand according to the women's social background. We saw a social gradient in contraceptives changes. The decline in the use of contraceptive methods available under medical prescription was particularly marked for women from lower and higher classes in which we observe a decrease in pill use between 2010 and 2013, whereas it was observed only between 2013 and 2016 among middle class women. Moreover, while some women from upper class shifted from pill to IUD between 2010 and 2013, this was not the case for their less privileged counterparts. As a consequence, it seems that the French "pill scare" led to the reshaping of social inequalities in access to medical contraceptives

Cellular Antioxidant Effect of an Aronia Extract and Its Polyphenolic Fractions Enriched in Proanthocyanidins, Phenolic Acids, and Anthocyanins

Oxidative stress and chronic inflammation contribute to some chronic diseases. Aronia berries are rich in polyphenols. The aim of the present study was to characterize the cellular antioxidant effect of an aronia extract to reflect the potential physiological in vivo effect. Cellular in vitro assays in three cell lines (Caco-2, HepG2, and SH-SY5Y) were used to measure the antioxidant effect of AE, in three enriched polyphenolic fractions (A1: anthocyanins and phenolic acids; A2: oligomeric proanthocyanidins; A3: polymeric proanthocyanidins), pure polyphenols and microbial metabolites. Both direct (intracellular and membrane radical scavenging, catalase-like effect) and indirect (NRF2/ARE) antioxidant effects were assessed. AE exerted an intracellular free radical scavenging activity in the three cell lines, and A2 and A3 fractions showed a higher effect in HepG2 and Caco-2 cells. AE also exhibited a catalase-like activity, with the A3 fraction having a significant higher activity. Only A1 fraction activated the NRF2/ARE pathway. Quercetin and caffeic acid are the most potent antioxidant polyphenols, whereas cyanidin and 5-(3′,4′-dihydroxyphenyl)-γ-valerolactone showed the highest antioxidant effect among polyphenol metabolites. AE rich in polyphenols possesses broad cellular antioxidant effects, and proanthocyanidins are major contributors. Polyphenol metabolites may contribute to the overall antioxidant effect of such extract in vivo

The French pill scare and the reshaping of social inequalities in access to medical contraceptives

While the consequences of various “pill scares” have been relatively well-documented in the public health literature revealing a drop in pill use and a rise in unplanned pregnancies and abortion rates, researchers rarely considered that these controversies would affect women contraceptive practices differently according to their social background. Indeed, social differentiations in reaction to “pill scares” could contribute to reinforce the social gradient in the use of contraceptive methods and choice of visiting the health professionals who prescribe them. These could contribute to an increase in health inequalities on access to contraceptive methods. Using data from three state nationally representative cross-sectional surveys conducted in France in 2010, 2013 and 2016, we studied the changes in women's contraceptive uses around the French “pill scare” that occurred in 2012–2013. We focused on the changes in the use of all contraceptives available under medical prescription (called medical contraceptives) on one hand, and on each specific method (pill, IUD, implant, patch or vaginal ring, and female sterilization) on the other hand according to the women's social background. We saw a social gradient in contraceptives changes. The decline in the use of contraceptive methods available under medical prescription was particularly marked for women from lower and higher classes in which we observe a decrease in pill use between 2010 and 2013, whereas it was observed only between 2013 and 2016 among middle class women. Moreover, while some women from upper class shifted from pill to IUD between 2010 and 2013, this was not the case for their less privileged counterparts. As a consequence, it seems that the French “pill scare” led to the reshaping of social inequalities in access to medical contraceptives