Membre du comité d'organisation logistique et scientifique

visioconférence, France, 6-9 octobre 2020; International audience

DIAGSOL Development of a new functional marker for B-triketone herbicides exposure in agricultural soils

International audience; The-triketone herbicides are maize selective herbicides that have been largely applied in replacement of atrazine, banned in Europe in 2004. Their mode of action lays on the inhi- bition of the p-hydroxyphenylpyruvate dioxygenase (HPPD), a key enzyme of the carotenoid biosynthesis.In recent studies, we showed that within the soil bacterial community, many microorganisms possess a functional HPPD enzyme involved in tyrosine metabolism. These ”non-target or- ganisms” harbor the target of the-triketone herbicides and consequently may be affected in response to its exposure. From this point of view, the bacterial community harboring the hppd gene might be a relevant mark…

Development of a new functional marker for β-triketone herbicides exposure in agricultural soils

The β-triketone herbicides are maize selective herbicides that have been largely applied in replacement of atrazine, banned in Europe in 2003. Their mode of action lays on the inhibition of the p-hydroxyphenylpyruvate dioxygenase (HPPD), a key enzyme of the carotenoid biosynthesis. In recent studies, we showed that within the soil bacterial community, many microorganisms possess a functional HPPD enzyme involved in tyrosine metabolism. These “non-target organisms” harbor the target of the β-triketone herbicides and consequently may be affected in response to its exposure. Within this context, the objective of our work is to check for the interest of hppd bacterial community as a marker of e…

A new tool to assess the ecotoxicological impact of β-triketone herbicides on soil microbial communities

International audience; The β-triketone herbicides are post-emergence maize selective herbicides that have beenintroduced on the market, in replacement of atrazine, banned in Europe in 2004. Qualified as “eco-friendly”, since they are based on natural phytotoxin properties, these herbicides target an enzymeinvolved in carotenoid biosynthesis called 4-hydroxyphenylpyruvate dioxygenase (HPPD) encoded bythe hppd gene. The inhibition of this enzyme provokes bleaching symptoms, necrosis and death ofweeds.The hppd gene is not only find in eukaryotes such as plants, animals and humans but also inprokaryotes such as fungi, yeasts and bacteria. In recent studies, we showed that, within the soil bact…

DIAGSOL : Développement d’un outil microbien pour évaluer l’exposition des sols agricoles aux herbicides β-tricétones

International audience; En 2011, en France, plus de 2 millions d’hectares de champs de maïs ont été traités avec desherbicides β-tricétones. Qualifiés de « respectueux de l’environnement » en raison d’une efficacité àfaible dose, de récentes études ont démontré un effet transitoire des β-tricétones sur la diversitébactérienne des sols (Romdhane et al., 2016). L’utilisation récurrente des β-tricétones pourrait, àterme, perturber la diversité bactérienne et les fonctions écosystémiques des sols qu’elle soutient.Il est essentiel d’évaluer l’exposition des microorganismes des sols aux β-tricétones.L’enzyme 4-hydroxyphénylpyruvate dioxygénase (4-HPPD), cible de ces herbicides chez les plantesadv…

Response of soil bacterial and hppd communities to tembotrione herbicide

Herbicides used in agriculture aim to prevent weed growth but are known to end up in contactwith soil microorganisms, thus defined as non-target organisms. Tembotrione, a recentlymarketed β-triketone herbicide, is known to inhibit the 4-HydroxyPhenylPyruvateDioxygenase(4-HPPD) in weeds. This enzyme is also found in numerous soil microorganisms, such as somePGPR and symbiotic bacteria, that play a key role in maintenance of ecosystem services.In this study, one of the major concerns is to assess whether tembotrione could have toxiceffects on soil microorganisms and could disturb soil microbial community dynamic andstructure. To investigate the possible impacts of this herbicide on these comm…

Bacterial hppd: a biomarker of exposure of soils to beta-triketone herbicides?

National audience; β-triketone herbicides are among the most used herbicides in corn crop to control broadleaf weeds.These herbicides inhibit the 4-hydroxyphenylpyruvate dioxygenase (4-HPPD) and lead to bleaching anddeath of weeds. This enzyme is not only found in plants but in all living organisms, includingmicroorganisms where it takes part to the tyrosine degradation pathway. Thus, microorganismsclassified as “non-target organisms” by current EU regulation for pesticide authorization, might beimpacted by β-triketones, with possible domino effect on microbial functions supporting soilecosystem services (Thiour-Mauprivez et al. 2019). Since microorganisms have been proposed by EFSAas key-d…

Biodegradation of synthetic β-triketone herbicide

Fate, biodegradation and ecotoxicological impact of the bioherbicide leptospermone on soil bacterial community

International audience

Isolation and characterisation of a bacterial strain degrading the herbicide sulcotrione from an agricultural soil

BACKGROUND: The dissipation kinetics of the herbicide sulcotrione sprayed 4 times on a French soil was studied using a laboratory microcosm approach. An advanced cultivation-based method was then used to isolate the bacteria responsible for biotransformation of sulcotrione. Chromatographic methods were employed as complementary tools to define its metabolic pathway. RESULTS: Soil microflora was able quickly to biotransform the herbicide (DT50 ≈ 8 days). 2-Chloro-4-mesylbenzoic acid, one of its main metabolites, was clearly detected. However, no accelerated biodegradation process was observed. Eight pure sulcotrione-resistant strains were isolated, but only one (1OP) was capable of degrading…

Impact of Leptospermone, a Natural β-Triketone Herbicide, on the Fungal Composition and Diversity of Two Arable Soils

Impact of leptospermone, a β-triketone bioherbicide, was investigated on the fungal community which supports important soil ecological functions such as decomposition of organic matter and nutrients recycling. This study was done in a microcosm experiment using two French soils, Perpignan (P) and Saint-Jean-de-Fos (SJF), differing in their physicochemical properties and history treatment with synthetic β-triketones. Soil microcosms were treated with leptospermone at recommended dose and incubated under controlled conditions for 45 days. Untreated microcosms were used as control. Illumina MiSeq sequencing of the internal transcribed spacer region of the fungal rRNA revealed significant chang…

Impact of Leptospermone, a Natural β-Triketone Herbicide, on the Fungal Composition and Diversity of Two Arable Soils

International audience; Impact of leptospermone, a β-triketone bioherbicide, was investigated on the fungal community which supports important soil ecological functions such as decomposition of organic matter and nutrients recycling. This study was done in a microcosm experiment using two French soils, Perpignan (P) and Saint-Jean-de-Fos (SJF), differing in their physicochemical properties and history treatment with synthetic β-triketones. Soil microcosms were treated with leptospermone at recommended dose and incubated under controlled conditions for 45 days. Untreated microcosms were used as control. Illumina MiSeq sequencing of the internal transcribed spacer region of the fungal rRNA re…