Biology subjects

Devers, M.

Publications and source records attributed to Devers, M..

5 recordsLinked to original sources

bioRxiv2025

Effects of a Sequential Application of Plant Protection Products on Soil Microbes and Free-Living Nematodes in a Field Experiment

During crop growth cycle, often several different plant protection products (PPPs) are applied, in combination or sequentially. Such sequential applications result in unintentional mixtures of residues that may affect ecosystem services supported by non-target organisms such as soil microbes and nematodes. This scenario of sequential PPP application is frequent in agricultural practice but rarely addressed experimentally at field scale with regard to environmental impacts. The objective of this study was to evaluate the effect of individual and sequential application of three PPPs (the herbicide clopyralid, the insecticide zeta-cypermethrin, and the fungicide pyraclostrobin) on soil microbial communities, and on the abundance of free-living nematode. Single applications (at 1x or 10x the agronomical dose) were made to triplicated field plots with each one of the PPPs or all three PPPs in sequence, with untreated plots serving as controls. Plots were sampled prior to each application, and 7 and 28 days thereafter. The fungal communitys composition and abundance were found to be more susceptible than the bacterial community to PPP applications, while the bacterial was mainly driven by the in-field heterogeneity of soil properties. Transient effects of PPP applications were detected on nematode abundance. Higher tier ecotoxicological studies offer greater ecological relevance compared to the standard laboratory tests but are challenged by environmental variations that should be accounted for when evaluating the ecotoxicity of pesticides on soil organisms.

ecology↗

bioRxiv2025

Molecular mechanisms underlying the early steps of floral initiation in seasonal flowering genotypes of cultivated strawberry

Floral initiation is required for sexual reproduction in angiosperm plants, and has a significant impact on crop yields. In cultivated strawberry, the molecular basis of floral initiation is poorly understood and most studies have focused on a single genotype grown under controlled conditions. To gain more insight into this process, we conducted a study under natural conditions in two countries using two seasonal flowering cultivars. We focused on the early steps of floral initiation by using samples spanning key developmental stages of the shoot apical meristem. The analysis of differential gene expression in leaf and terminal bud tissues revealed enrichment for genes involved in carbohydrate metabolism and phytohormone pathways in leaves. Other protein classes that were enriched during early floral initiation were associated with cytoskeleton organization, cell cycle regulation, and chromatin structure. We also identified genes associated with the photoperiodic pathway, well-characterized floral integrators such as TFL1 and SOC1, and several linked to phytohormone regulation, such as XTH23, PP2 and EIN3.

plant biology↗

bioRxiv2024

Evaluating the Effects of Environmental Disturbances and Pesticide Mixtures on Soil Microbial Endpoints

Pesticides are widely used in conventional agriculture, either applied separately or in combination during the culture cycle. Due to their occurrence and persistence in soils, pesticide residues may have an impact on soil microbial communities and on supported ecosystem services. In this regard, the EFSA (European Food Safety Authority) recently published a scientific opinion inciting to change pesticide risk assessment to better protect soil microbe-mediated processes. Climate change is another major concern for all living organisms including soil microbial community stability. Extreme climatic events, such as heat waves or heavy rainfalls, are becoming more and more frequent and their impact on soil microbial diversity and functions have already been demonstrated. The objectives of this study were to evaluate the effects of temperature and humidity disturbances and pesticide active ingredients exposure on soil microbial community structure and functions. To this end, 250 soil microcosms were exposed to either a heat disturbance, a high humidity to mimic heavy rain, or no environmental disturbance. After three days of recovery, soil microcosms were treated with different active ingredients: clopyralid (herbicide), cypermethrin (insecticide) and pyraclostrobin (fungicide). The treatments were applied alone or in combination at 1x or 10x of the agronomical dose. We then evaluated the effects of the disturbances and the active ingredients on various microbial endpoints related to the diversity and the structure of soil microbial communities, and with a specific focus on microbial guilds involved in nitrification. Overall, we demonstrated that the impact of environmental disturbances applied to soil microcosms, especially heat, on microbial endpoints was stronger than that of the active ingredients applied alone or in combinations. Compounded effects of environmental disturbances and active ingredients were detected, but sparsely and were of small scale for the chosen pesticides and applied doses.

microbiology↗

bioRxiv2021

Community diversity determines the evolution of synthetic bacterial communities under artificial selection

Artificial selection can be conducted at the community level in the laboratory through a differential propagation of the communities according to their level of expression of a targeted function (i.e. community phenotype). Working with communities instead of individuals as selection units brings in additional sources of variation in the considered phenotype that can arise through changes in community structure and influence the outcome of the artificial selection. These sources of variation could even be increased by manipulating species diversity. In this study, we wanted to assess the effect of manipulating initial community richness on artificial selection efficiency, defined as the change in the targeted function over time as compared to a control treatment without artificial selection. We applied artificial selection for a high productivity on synthetic bacterial communities varying for their initial richness level (from one to 16 strains). Our results showed that, overall, the communities that were artificially selected were 16% more productive than the control communities. Community richness positively influenced community productivity and metabolic capacities and was a strong determinant of the dynamics of community evolution. Our results suggested that community richness could influence artificial selection efficiency but a convergence of the community composition might have limited the effect of diversity on artificial selection efficiency. We propose that applying artificial selection on communities varying for their diversity could allow to find communities differing for their level of expression of a function but also for their responsiveness to artificial selection, provided that their initial composition is different enough.

evolutionary biology↗

bioRxiv2019

Labour sharing promotes coexistence in atrazine degrading bacterial communities

Microbial communities exert a pivotal role in the biodegradation of xenobiotics including pesticides1. In the case of atrazine, multiple studies have shown that its degradation involved a consortia rather than a single species2,3,4,5, but little is known about how interdependency between the species composing the consortium is set up. The Black Queen Hypothesis (BQH) formalized theoretically the conditions leading to the evolution of dependency between species6: members of the community called helpers provide publicly common goods obtained from the costly degradation of a compound, while others called beneficiaries take advantage of the public goods, but lose access to the primary resource through adaptive degrading gene loss. Here, we test whether liquid media supplemented with the herbicide atrazine could support coexistence of bacterial species through BQH mechanisms. We observed the establishment of dependencies between species through atrazine degrading gene loss. Labour sharing between members of the consortium led to coexistence of multiple species on a single resource and improved atrazine degradation potential. Until now, pesticide degradation has not been approached from an evolutionary perspective under the BQH framework. We provide here an evolutionary explanation that might invite researchers to consider microbial consortia, rather than single isolated species, as an optimal strategy for isolation of xenobiotics degraders. Also, we anticipate that future research should focus on the bioaugmentation with stabilized and tightly structured microbial degrading consortia as an effective solution for in situ bioremediation of sites polluted with recalcitrant compounds.

evolutionary biology↗