Search Results (3)

Apera spica-venti, a prevalent weed in Czech winter wheat fields, has developed resistance to ALS-inhibiting herbicides due to their frequent use. This study reports a biotype of A. spica-venti resistant to pyroxsulam, with cross and multiple resistance to iodosulfuron, propoxycarbazone, pinoxaden, and chlortoluron. Dose–response experiments revealed high resistance of both R1 and R2 biotypes to pyroxsulam, with resistance factors (RF) of 6.69 and 141.65, respectively. Pre-treatment with malathion reduced RF by 2.40× and 1.25× in R1 and R2, indicating the potential involvement of cytochrome P450 (CytP450). NBD-Cl pre-treatment decreased RF only in R2, suggesting possible GST involvement. Gene analysis revealed no mutations (at previously reported sites) or overexpression in the acetolactate synthase (ALS) gene. However, a significant difference in ALS enzyme activity between resistant and susceptible biotypes points to target-site resistance mechanisms. Studies with ¹⁴C-labeled pyroxsulam showed that reduced absorption and translocation were not likely resistance mechanisms. In summary, herbicide resistance in A. spica-venti appears to result from multiple mechanisms. Possible causes include target-site resistance from an unidentified ALS mutation (within coding or regulatory regions). Enhanced herbicide metabolism via CytP450s and GSTs is also a contributing factor. Further experimental validation is needed to confirm these mechanisms and fully understand the resistance. This evolution underscores the adaptive capacity of weed populations under herbicide pressure, emphasizing the need for alternative control strategies. Full article

Chlortoluron (3-(3-chloro-p-tolyl)-1,1-dimethyl urea) is an herbicide widely used in substitution to isoproturon to control grass weed in wheat and barley crops. Chlortoluron has been detected in groundwaters for more than 20 years; and dramatic increases in concentrations are observed after intense rain outbreaks. In this context; we developed an immunosensor for the determination of chlortoluron based on competitive binding of specific monoclonal antibodies on chlortoluron and immobilized biotinylated chlortoluron; followed by electrochemical detection on screen-printed carbon electrodes. The optimized immunosensor exhibited a logarithmic response in the range 0.01–10 µg·L⁻¹; with a calculated detection limit (LOD) of 22.4 ng·L⁻¹; which is below the maximum levels allowed by the legislation (0.1 µg·L⁻¹). The immunosensor was used for the determination of chlortoluron in natural groundwaters, showing the absence of matrix effects. Full article

Protoporphyrinogen oxidase (PPO) has been identified as one of the most promising targets for herbicide discovery. A series of novel phthalimide derivatives were designed by molecular docking studies targeting the crystal structure of mitochondrial PPO from tobacco (mtPPO, PDB: 1SEZ) by using Flumioxazin as a lead, after which the derivatives were synthesized and characterized, and their herbicidal activities were subsequently evaluated. The herbicidal bioassay results showed that compounds such as 3a (2-(4-bromo-2,6-difluorophenyl) isoindoline-1,3-dione), 3d (methyl 2-(4-chloro-1,3-dioxoisoindolin-2-yl)-5-fluorobenzoate), 3g (4-chloro-2-(5-methylisoxazol-3-yl) isoindoline-1,3-dione), 3j (4-chloro-2-(thiophen-2-ylmethyl) isoindoline-1,3-dione) and 3r (2-(4-bromo-2,6-difluorophenyl)-4-fluoroisoindoline-1,3-dione) had good herbicidal activities; among them, 3a showed excellent herbicidal efficacy against A. retroflexus and B. campestris via the small cup method and via pre-emergence and post-emergence spray treatments. The efficacy was comparable to that of the commercial herbicides Flumioxazin, Atrazine, and Chlortoluron. Further, the enzyme activity assay results suggest that the mode of action of compound 3a involves the inhibition of the PPO enzyme, and 3a showed better inhibitory activity against PPO than did Flumioxazin. These results indicate that our molecular design strategy contributes to the development of novel promising PPO inhibitors. Full article