6533b82efe1ef96bd12942c1

RESEARCH PRODUCT

Response of soil bacterial and hppd communities to tembotrione herbicide

subject

description

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 communities, a soilmicrocosm approach was performed using 1-fold or 10-fold the recommended tembotrioneagronomical dose (RAD).Soil samples were collected at day 0, 3, 7, 14, 24, 40, and 55 to determine the followingendpoints: (i) dissipation of the active ingredient in soil, (ii) bacterial diversity with highthroughput sequencing of the 16S rDNA, (iii) hppd community diversity with high throughputsequencing of the hppd gene using degenerated primers designed by our own. Moreover, aculturable approach was applied to soil microcosm samples to study antibiotic resistance (ABR)of isolated soil bacteria, and to screen for HPPD+ strains.Whatever the treatment applied, tembotrione was fully dissipated from soil after 24 days at1*RAD with a DT50 of 7 days, and after 55 days at 10*RAD with a DT50 of 15 days. Interestingly,among the culturable strains isolated from the microcosms, 29 presenting ABR, were alsoHPPD+. Further studies are currently performed to characterize their sensitivity to β-triketonesherbicides, and their resistance to antibiotics. Finally, microbial and hppd diversity analyseswith sequencing data are still ongoing at the time of writing this abstract, but results should beavailable by October 2022.