Introduction
Rimisoxafen is a novel herbicidal compound developed by FMC Agricultural Solutions to combat the increasing prevalence of herbicide-resistant weeds in modern agriculture. It belongs to the pyrimidinyloxy benzene class and was officially approved under ISO 1750 in March 2021, classified among thiocarbamate herbicides. According to the Herbicide Resistance Action Committee (HRAC), rimisoxafen is designated under Group 12 for inhibition of phytoene desaturase (PDS) and Group 32 for inhibition of solanesyl diphosphate synthase (SDPS).
Rimisoxafen induces a characteristic leaf-bleaching phenotype, which led researchers to investigate its underlying mode of action. Subsequent studies confirmed that rimisoxafen inhibits both PDS and SDPS—two key enzymes essential for carotenoid and plastoquinone biosynthesis, respectively. These findings were validated through comprehensive in vitro and in vivo analyses, revealing distinct metabolomic signatures for each enzyme’s inhibition.
Significantly, rimisoxafen maintains herbicidal activity against weed strains resistant to either PDS or SDPS inhibitors individually. Resistance was observed only in strains containing mutations in both targets, demonstrating the effectiveness of this dual-target strategy in delaying resistance development. Additionally, the single-molecule dual inhibition approach offers potential to reduce herbicide load in the field, especially in corn and soybean cropping systems.
Mode of Action and Biochemical Significance
🔬 1. Solanesyl Diphosphate Synthase (SDPS) – HRAC Group 32
- Biological Role: SDPS is a key enzyme in the biosynthesis of plastoquinone, which serves as an electron carrier in the photosynthetic electron transport chain and a cofactor in carotenoid biosynthesis.
- Herbicidal Impact: Inhibition of SDPS impairs photosynthesis, induces oxidative stress, and results in chlorosis and plant death.
- Resistance Value: SDPS remains a relatively novel herbicidal target, making it valuable for use against populations resistant to traditional herbicide classes like photosystem II (PSII) and EPSPS inhibitors.
🌿 2. Phytoene Desaturase (PDS) – HRAC Group 12
- Biological Role: PDS catalyzes a crucial desaturation step in the carotenoid biosynthetic pathway, producing compounds that protect chlorophyll from light-induced oxidative damage.
- Herbicidal Impact: Blocking PDS depletes carotenoids, leading to leaf bleaching and photooxidative destruction of plant tissues.
- Current Status: Although PDS is a known herbicidal target (e.g., norflurazon), resistance in certain weed populations has made dual-action solutions increasingly necessary.
Why Dual Inhibition Matters in Crop Protection
🧬 1. Built-in Resistance Management
Rimisoxafen’s ability to inhibit two independent biochemical targets significantly lowers the risk of rapid resistance development. Studies in Chlamydomonas reinhardtii revealed that only strains with combined SDPS and PDS mutations exhibited resistance, confirming the resilience of this dual-site mechanism.
🌾 2. Broad-Spectrum Weed Control
The dual-target approach broadens rimisoxafen’s spectrum of activity across multiple weed species, including those already resistant to single-site herbicides.
♻️ 3. Lower Environmental Load
By consolidating two herbicidal modes of action into a single molecule, rimisoxafen may reduce the need for herbicide mixtures, thereby minimizing application rates and environmental residues.
Conclusion
Rimisoxafen exemplifies a next-generation herbicide designed to meet the agronomic demands of resistance management, efficacy, and environmental stewardship. Through simultaneous inhibition of PDS and SDPS, this molecule offers a powerful solution to current weed control challenges in major cropping systems. FMC’s innovation reflects a strategic leap forward in the development of sustainable crop protection technologies.
References
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Kang, I.-H., Brabham, C., Lee, J., Wu, L., Lu, Q., Yan, M., Lai, P.-S., Rhoades, D. F., Nesnow, D., Jeffrey, S., McGonigle, B., Kim, S.-I., Andreassi, J. L., Pember, S. O., Gutteridge, S., Emptage, R. P. (2025). Dual mode of action herbicide rimisoxafen targets both phytoene desaturase and solanesyl diphosphate synthase. FMC Agricultural Solutions, Stine Research Center, Newark, DE, USA.
Published: June 09, 2025 | DOI: https://doi.org/10.1002/ps.8972
Received: April 2, 2025 | Revised: May 16, 2025
