114 research outputs found
StratĂ©gies dâacquisition des ressources des plantes prairiales sous contraintes hydrique et minĂ©rale - RĂŽle du systĂšme racinaire dans la rĂ©ponse aux facteurs structurant les communautĂ©s
A lâheure oĂč lâon cherche Ă optimiser les services Ă©co-systĂ©miques fournis par les prairies, une meilleure comprĂ©hension du fonctionnement des systĂšmes racinaires apparait comme nĂ©cessaire. Nous avons donc dĂ©cidĂ© de caractĂ©riser les stratĂ©gies dâespĂšces issues des familles des Fabaceae et Poaceae prairiales par la mesure de traits fonctionnels racinaires. Le principal rĂ©sultat de ce travail est la mise en Ă©vidence de plusieurs axes majeurs de diffĂ©rentiation des stratĂ©gies racinaires et de leurs relations avec les exigences Ă©cologiques des espĂšces. Le plus important est le compromis entre stratĂ©gies de capture et de conservation des ressources. Les espĂšces Ă stratĂ©gie de capture sont mieux adaptĂ©es aux milieux peu stressants notamment pour lâeau, mais sont peu impactĂ©es par le manque de phosphore, ce sont aussi des compĂ©titrices efficaces. Bien que les plantes Ă stratĂ©gie de conservation soient mieux Ă mĂȘme de se dĂ©velopper dans des milieux continentaux, elles sont plus impactĂ©es que les autres par la prĂ©sence de compĂ©titeurs et le manque de phosphore. Le type de relations existant entre les stratĂ©gies aĂ©riennes et racinaires apparait aussi comme un marqueur de lâadaptation des plantes aux stress. LâĂ©tude du systĂšme racinaire est donc un moyen efficace de prĂ©dire le comportement des espĂšces de plantes prairiales face Ă des contraintes abiotiques et biotiques. Cela ouvre des perspectives particuliĂšrement intĂ©ressantes notamment pour la construction de mĂ©langes dâespĂšces mieux adaptĂ©es Ă leurs environnements. ABSTRACT : In order to optimise grassland ecosystem services we need to improve our understanding of root system functioning. As a result, we decided to characterise strategies of species coming from grasslandâ Fabaceae and Poaceae families, by root functional traits measurement. The main result of this work is the establishment of several axes of root strategies differentiation. The main axis is the trade-off between resources capture and conservation strategies. Species with capture strategies appear to be adapted to non-water stressful habitat and are barely impacted by phosphorus shortage; they also happen to be strong competitors. On the opposite, species with conservation strategies are adapted to water stressful continental climates, but are strongly impacted by phosphorus shortage and happen to be weak competitors. The kind of relation between above-ground and below-ground strategies also appears to be a marker of the plants adaptation to stress. We showed that the root system study is a good way to predict grassland species comportment to face abiotic and biotic constraints. The present work widens interesting perspectives for the sowing of mixed grassland species better adapted to their environments
Multiple facets of diversity effects on plant productivity: species richness, functional diversity, species identity and intraspecific competition
International audienc
Stratégies d'acquisition des ressources des plantes prairiales sous contraintes hydrique et minérale - RÎle du systÚme racinaire dans la réponse aux facteurs structurant les communautés
A l heure oĂč l on cherche Ă optimiser les services Ă©co-systĂ©miques fournis par les prairies, une meilleure comprĂ©hension du fonctionnement des systĂšmes racinaires apparait comme nĂ©cessaire. Nous avons donc dĂ©cidĂ© de caractĂ©riser les stratĂ©gies d espĂšces issues des familles des Fabaceae et Poaceae prairiales par la mesure de traits fonctionnels racinaires. Le principal rĂ©sultat de ce travail est la mise en Ă©vidence de plusieurs axes majeurs de diffĂ©rentiation des stratĂ©gies racinaires et de leurs relations avec les exigences Ă©cologiques des espĂšces. Le plus important est le compromis entre stratĂ©gies de capture et de conservation des ressources. Les espĂšces Ă stratĂ©gie de capture sont mieux adaptĂ©es aux milieux peu stressants notamment pour l eau, mais sont peu impactĂ©es par le manque de phosphore, ce sont aussi des compĂ©titrices efficaces. Bien que les plantes Ă stratĂ©gie de conservation soient mieux Ă mĂȘme de se dĂ©velopper dans des milieux continentaux, elles sont plus impactĂ©es que les autres par la prĂ©sence de compĂ©titeurs et le manque de phosphore. Le type de relations existant entre les stratĂ©gies aĂ©riennes et racinaires apparait aussi comme un marqueur de l adaptation des plantes aux stress. L Ă©tude du systĂšme racinaire est donc un moyen efficace de prĂ©dire le comportement des espĂšces de plantes prairiales face Ă des contraintes abiotiques et biotiques. Cela ouvre des perspectives particuliĂšrement intĂ©ressantes notamment pour la construction de mĂ©langes d espĂšces mieux adaptĂ©es Ă leurs environnements.In order to optimise grassland ecosystem services we need to improve our understanding of root system functioning. As a result, we decided to characterise strategies of species coming from grassland Fabaceae and Poaceae families, by root functional traits measurement. The main result of this work is the establishment of several axes of root strategies differentiation. The main axis is the trade-off between resources capture and conservation strategies. Species with capture strategies appear to be adapted to non-water stressful habitat and are barely impacted by phosphorus shortage; they also happen to be strong competitors. On the opposite, species with conservation strategies are adapted to water stressful continental climates, but are strongly impacted by phosphorus shortage and happen to be weak competitors. The kind of relation between above-ground and below-ground strategies also appears to be a marker of the plants adaptation to stress. We showed that the root system study is a good way to predict grassland species comportment to face abiotic and biotic constraints. The present work widens interesting perspectives for the sowing of mixed grassland species better adapted to their environments.TOULOUSE-INP (315552154) / SudocSudocFranceF
Mitochondrial permeabilization engages NF-ÎșB-dependent anti-tumour activity under caspase deficiency
Apoptosis represents a key anti-cancer therapeutic effector mechanism. During apoptosis, mitochondrial outer membrane permeabilization (MOMP) typically kills cells even in the absence of caspase activity. Caspase activity can also have a variety of unwanted consequences that include DNA damage. We therefore investigated whether MOMP-induced caspase-independent cell death (CICD) might be a better way to kill cancer cells. We find that cells undergoing CICD display potent pro-inflammatory effects relative to apoptosis. Underlying this, MOMP was found to stimulate NF-ÎșB activity through the downregulation of inhibitor of apoptosis proteins. Strikingly, engagement of CICD displays potent anti-tumorigenic effects, often promoting complete tumour regression in a manner dependent on intact immunity. Our data demonstrate that by activating NF-ÎșB, MOMP can exert additional signalling functions besides triggering cell death. Moreover, they support a rationale for engaging caspase-independent cell death in cell-killing anti-cancer therapies
Intraspecific functional trait variation and performance of <em>Populous tremuloides</em>
International audienc
Grounding traitâbased root functional ecology
International audienceA growing need exists to consider effects of biodiversity dynamics on the functioning of natural and anthropised ecosystems. This requires including the concepts of functional ecology, especially comparative trait-based ecology, in a broad range of theoretical and applied studies. In parallel, the importance of the belowground compartment is increasingly recognised, which has exponentially increased the number of studies that consider root functional traits, despite limited understanding of their meaning. This perspective article i) describes the origins of the trait-based ecology framework, ii) highlights current limitations of rootsystem studies, and iii) recommends ways to address these limitations. In recent years, studies claimed that aboveground functional ecology had theoretical foundations without adequate empirical support. Root functional ecology has experienced the same problems and, for several reasons, its foundations seem even more unstable. Firstly, roots are difficult to collect, and it is difficult to precisely define components of the root system that have homogenous functions. Secondly, root systems are complex organs and have a diversity of functions, such as taking up nutrients and water, storing resources, and anchoring plants. Thirdly, the theoretical background used in root functional ecology approaches is based on that of aboveground ecology, specifically leaf functional ecology. In the past several decades, root ecology benefitted from following in the footsteps of aboveground trait-based functional ecology, which highlighted the existence of a variety of trait spectra that were partially related to species' ecology or their interaction with symbiotic microorganisms. However, root functional ecology is currently at a crossroads and must move beyond this aboveground path and rediscover the origins of root ecology and include new traits based on root architecture and anatomy. Doing so requires developing innovative approaches that are more specific to the belowground compartment to improve understanding of plant roots and include them in large-scale studies
Grassland speciesâ resources acquisition strategies under hydric and mineral stress - part of the root system in the response to communitiesâ structuring factors
A lâheure oĂč lâon cherche Ă optimiser les services Ă©co-systĂ©miques fournis par les prairies, une meilleure comprĂ©hension du fonctionnement des systĂšmes racinaires apparait comme nĂ©cessaire. Nous avons donc dĂ©cidĂ© de caractĂ©riser les stratĂ©gies dâespĂšces issues des familles des Fabaceae et Poaceae prairiales par la mesure de traits fonctionnels racinaires. Le principal rĂ©sultat de ce travail est la mise en Ă©vidence de plusieurs axes majeurs de diffĂ©rentiation des stratĂ©gies racinaires et de leurs relations avec les exigences Ă©cologiques des espĂšces. Le plus important est le compromis entre stratĂ©gies de capture et de conservation des ressources. Les espĂšces Ă stratĂ©gie de capture sont mieux adaptĂ©es aux milieux peu stressants notamment pour lâeau, mais sont peu impactĂ©es par le manque de phosphore, ce sont aussi des compĂ©titrices efficaces. Bien que les plantes Ă stratĂ©gie de conservation soient mieux Ă mĂȘme de se dĂ©velopper dans des milieux continentaux, elles sont plus impactĂ©es que les autres par la prĂ©sence de compĂ©titeurs et le manque de phosphore. Le type de relations existant entre les stratĂ©gies aĂ©riennes et racinaires apparait aussi comme un marqueur de lâadaptation des plantes aux stress. LâĂ©tude du systĂšme racinaire est donc un moyen efficace de prĂ©dire le comportement des espĂšces de plantes prairiales face Ă des contraintes abiotiques et biotiques. Cela ouvre des perspectives particuliĂšrement intĂ©ressantes notamment pour la construction de mĂ©langes dâespĂšces mieux adaptĂ©es Ă leurs environnements.In order to optimise grassland ecosystem services we need to improve our understanding of root system functioning. As a result, we decided to characterise strategies of species coming from grasslandâ Fabaceae and Poaceae families, by root functional traits measurement. The main result of this work is the establishment of several axes of root strategies differentiation. The main axis is the trade-off between resources capture and conservation strategies. Species with capture strategies appear to be adapted to non-water stressful habitat and are barely impacted by phosphorus shortage; they also happen to be strong competitors. On the opposite, species with conservation strategies are adapted to water stressful continental climates, but are strongly impacted by phosphorus shortage and happen to be weak competitors. The kind of relation between above-ground and below-ground strategies also appears to be a marker of the plants adaptation to stress. We showed that the root system study is a good way to predict grassland species comportment to face abiotic and biotic constraints. The present work widens interesting perspectives for the sowing of mixed grassland species better adapted to their environments
Plant ecological indicator values as predictors of fineâroot trait variations
International audienceFine roots play key roles in the capacity of plants to face environmental constraints and their traits reflect adaptations to the environment, including soil structure, resource availability and climate. However, the inaccuracy of global soil and climate databases to account for the large environmental variation occurring at small spatial scale prevents accurate estimations of the linkages between environmental variables and fine-root strategies. Here, using two global databases on fine-root traits (Rhizopolis-db) and species phylogenetic relatedness, and a regional database of species ecological indicator values (Baseflor), we quantified the predictive value of ecological indicator values, as an alternative to classical coarse soil and climate indicators, on the variation in four major fine-root traits. A strong phylogenetic signal was found among species for fine-root mean diameter, specific root length (SRL) and root tissue density (RTD), but less so for root nitrogen concentration (RNC). After accounting for this relatedness, ecological indicators still explained a large part of trait variation in our dataset for SRL, RTD and RNC. Multi-indicators best model R2 reached .40 for SRL and RTD, and .44 for RNC, whereas it was only 0.10 for diameter. Ecological indicators of nutrient availability and soil texture were those that most strongly related to SRL, RTD and RNC. Specifically, plant fast resources use strategies characterized by high SRL, RNC and low RTD occurred more frequently in nutrient-rich soils and in soils with light sandy textures. Additionally, light availability and atmospheric temperature were negatively related with SRL and continentality negatively influenced RNC. With respect to both nutrient and water availability ecological indicator values, opposite adaptations were observed between growth forms, particularly between woody and herbaceous species, limiting our ability to define simple, widely applicable patterns of traitâenvironment relationships. Synthesis. Our analysis demonstrates that species ecological indicator values are valuable predictors of plant below-ground strategies. It provides original evidence that herbaceous species with fine-root traits representative of fast resource use strategies typically occur in more favourable soil habitats (high nutrient and water availability); meanwhile, woody species may show the opposite trend. Other important environmental parameters concomitantly influence fine-root trait variation in contrasting ways
Root and shoot competition lead to contrasting competitive outcomes under water stress: AÂ systematic review and meta-analysis.
BACKGROUND:Competition is a critical process that shapes plant communities and interacts with environmental constraints. There are surprising knowledge gaps related to mechanisms that belie competitive processes, though important to natural communities and agricultural systems: the contribution of different plant parts on competitive outcomes and the effect of environmental constraints on these outcomes. OBJECTIVE:Studies that partition competition into root-only and shoot-only interactions assess whether plant parts impose different competitive intensities using physical partitions and serve as an important way to fill knowledge gaps. Given predicted drought escalation due to climate change, we focused a systematic review-including a meta-analysis on the effects of water supply and competitive outcomes. METHODS:We searched ISI Web of Science for peer-reviewed studies and found 2042 results. From which eleven suitable studies, five of which had extractable information of 80 effect sizes on 10 species to test these effects. We used a meta-analysis to compare the log response ratios (lnRR) on biomass for responses to competition between roots, shoots, and full plants at two water levels. RESULTS:Water availability treatment and competition treatment (root-only, shoot-only, and full plant competition) significantly interacted to affect plant growth responses (p < 0.0001). Root-only and full plant competition are more intense in low water availability (-1.2 and -0.9 mean lnRR, respectively) conditions than shoot-only competition (-0.2 mean lnRR). However, shoot-only competition in high water availability was the most intense (- 0.78 mean lnRR) compared to root-only and full competition (-0.5 and 0.61 mean lnRR, respectively) showing the opposite pattern to low water availability. These results also show that the intensity of full competition is similar to root-only competition and that low water availability intensifies root competition while weakening shoot competition. CONCLUSIONS:The outcome that competition is most intense between roots at low water availability emphasizes the importance of root competition and these patterns of competition may shift in a changing climate, creating further urgency for further studies to fil knowledge gaps addressing issues of drought on plant interactions and communities
Root and shoot competition lead to contrasting competitive outcomes under water stress: AÂ systematic review and meta-analysis
International audienceBackground: Competition is a critical process that shapes plant communities and interacts with environmental constraints. There are surprising knowledge gaps related to mechanisms that belie competitive processes, though important to natural communities and agricultural systems: the contribution of different plant parts on competitive outcomes and the effect of environmental constraints on these outcomes.Objective: Studies that partition competition into root-only and shoot-only interactions assess whether plant parts impose different competitive intensities using physical partitions and serve as an important way to fill knowledge gaps. Given predicted drought escalation due to climate change, we focused a systematic reviewâincluding a meta-analysis on the effects of water supply and competitive outcomes.Methods: We searched ISI Web of Science for peer-reviewed studies and found 2042 results. From which eleven suitable studies, five of which had extractable information of 80 effect sizes on 10 species to test these effects. We used a meta-analysis to compare the log response ratios (lnRR) on biomass for responses to competition between roots, shoots, and full plants at two water levels.Results: Water availability treatment and competition treatment (root-only, shoot-only, and full plant competition) significantly interacted to affect plant growth responses (p < 0.0001). Root-only and full plant competition are more intense in low water availability (-1.2 and -0.9 mean lnRR, respectively) conditions than shoot-only competition (-0.2 mean lnRR). However, shoot-only competition in high water availability was the most intense (â 0.78 mean lnRR) compared to root-only and full competition (-0.5 and 0.61 mean lnRR, respectively) showing the opposite pattern to low water availability. These results also show that the intensity of full competition is similar to root-only competition and that low water availability intensifies root competition while weakening shoot competition.Conclusions: The outcome that competition is most intense between roots at low water availability emphasizes the importance of root competition and these patterns of competition may shift in a changing climate, creating further urgency for further studies to fil knowledge gaps addressing issues of drought on plant interactions and communities
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