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Franck Dayan

Weed Science


Nutrien Distinguished Scholar of Agricultural Sciences

Office: 111 Weed Research Lab
Lab: 101 Weed Research Lab
Phone: 662.816.6214

Lab Website: Weed Science Lab

Research Interests

I joined the faculty of in January 2016 after a 20-year career as a research plant physiologist for the USDA-ARS.  I am interested in functional plant genomics and my research program encompasses applied projects on herbicide mode of action and evolution of resistance in weeds to more basic projects aiming to use genomic approaches to decipher traits imparting weediness (competition, cold and heat stress tolerance etc
).  I am also interested in the relative contribution of each of the 3 wheat genomes to specific pathways associated with primary metabolism.  My expertise in plant biochemistry and physiology as well as chemical ecology complements the efforts already in place in other groups at Colorado State University.

Courses I Teach

Plant Biochemistry in Agriculture

This course is intended for graduate students in the plant sciences, such as botany, plant ecology, crop science, weed science or horticulture, but it is opened to other students with general interest in plants.

This course offers students an experiential learning environment leading to an appreciation of the role of plant biochemistry in agriculture. The structure and function of enzymes in metabolic pathways and the contributions of these pathways to plant growth and development will be covered. To that end, students will become proficient in basic modeling of proteins. When appropriate, topics are taught as problem-based situations related to plant production, stress responses, chemical ecology and the production of secondary metabolites of importance to mankind. Students will be able to critically read the scientific literature pertaining to plant biochemistry and metabolism.


Herbicide Selectivity and Action

This is a fully asynchronous online course co-taught be Dr. Dayan and Dr Gaines. It is intended  for graduate students in the plant sciences, such as botany, plant ecology, crop science, weed science or horticulture, as well as students  with general interest in plants. The course is also intended for working professionals in industry, government, and consulting positions  with interest in herbicide use. This course will provide students with an experiential learning environment leading to mastery of how herbicides work and are used to  manage weeds. To that end, students will become proficient in the mechanisms of action of herbicides and their effects on primary metabolic processes. Students will investigate controversial issues associated with the use of herbicides and genetically modified herbicide-resistant crops.

Graduate Students I Advise


Srishti Gupta – PhD in Agricultural Biology

Catherine Traxler– PhD in Agricultural Biology

Amber Pelon – MS in Agricultural Biology


Past Graduate Students

Abigail Barker – PhD

Raven Bough – PhD

Hudson Takano – PhD

Mirella Farinelli Ortiz – PhD

Honors & Distinctions

Past President of the Phytochemical Society of North America, Past Treasurer of Phytochemical Society of North America and the International Weed Science Society, Associate editor of Weed Science and Pesticide Biochemistry and Physiology.  North American Editor of Outlooks on Pest Management.  2021 Nutrien Distinguished Professor in Agricultural Sciences,

2019 Colorado State University CAS Summit Team Research Award for Weed Science Team (Dayan, Gaines, Nissen, Westra), 2017 Molisch Award from the International Allelopathy Society,  2015 Outstanding Research Award from Weed Science Society of America, 2012 Senior Research Scientist of the Year (MSA) from USDA-ARS, 2006 Early Career Outstanding Scientist Award from the Weed Science Society of America, 2008 Grodzinsky Award from the International Allelopathy Congress, 2001 Early Career Research Scientist of the Year (MSA) from USDA-ARS.  Scientific refereed publications, 177; Other publications, 64.

Selected Publications

Herbicide Mode of Action and Mechanisms of Resistance

de Figueiredoa MRA, KĂŒpper A, Malone JM, Petrovic T., de Figueiredoa ABTB, Dayan FE, Campagnola G, Peersen OB, Prasad KVSK, Patterson EL, Reddy ASN, KubeĆĄ MF, Napier R, Preston C and Gaines TA 2022 An in-frame deletion in the degron tail of auxin co-receptor IAA2 confers resistance to the herbicide 2,4-D in Sisymbrium orientale. Proc Natl Acad Sci USA 119(9):e2105819119. doi:10.1073/pnas.2105819119

Bough RA, Gaines TA and Dayan FE 2022 Low temperature delays metabolism of quizalofop in resistant winter wheat and three annual grass weed species. Frontiers in Agronomy 3:800731.

Fipke MV, Da Rosa FeijĂł A, Garcia NS, Heck T, Viana VE, Dayan FE, Agostinetto D, Pinto Lamego F, Souza GM, Camargo ER and De Avila LA 2022 Transgenerational effect of drought stress and sub-lethal doses of quizalofop-p-ethyl: Decreasing sensitivity to herbicide and biochemical adjustment in Eragrostis plana. Agriculture 12, 396.

Bough RA and Dayan FE 2022 Biochemical and structural characterization of quizalofop-resistant wheat acetyl-CoA carboxylase. Scientific Reports 12:679.

Ortiz MF, Figueiredo MR, Nissen SJ, Wersal RM, Ratajczyk WA and Dayan FE. 2022. 2,4‐D and 2,4‐D butoxyethyl ester behavior in Eurasian and hybrid watermilfoil (Myriophyllum spp.). Pest Management Science. 78(2):626-32.

Duke SO and Dayan FE 2021 The search for new herbicide mechanisms of action – Is there a “holy grail”? Pest Management Science 78(4):1303-1313.

Takano HK, Ovejero RFL, Belchior GG, Maymone GPL and Dayan FE 2021. ACCase-inhibiting herbicides: mechanism of action, resistance evolution and stewardship. Scientia Agricola, 78(1) e20190102.

Alebrahim MT, Majd R, Abdollahi F, Zangoueinejad R, Dayan FE, Mathiassen SK and Kudsk P (2021) Absorption and metabolism of foliar-applied rimsulfuron in potato (Solanum tuberosum L.), common lambsquarters (Chenopodium album L.) and redroot pigweed (Amaranthus retroflexus L.).  Potato Research 64: 635–648

Barker AL, Barnes H and Dayan FE 2020 Conformation of the intermediates in the reaction catalyzed by protoporphyrinogen oxidase: An in silico analysis. International Journal of Molecular Sciences 21:9495.

Ortiz MF, Nissen SJ, Thum R, Heilman MA, Dayan FE. 2020. Current status and future prospects of herbicide for aquatic weed management. Outlooks on Pest Manage 31(6) 270-275.

Dayan FE and Duke SO 2020. Discovery for new herbicide sites of action by quantification of plant primary metabolite and enzyme pools.  Engineering 6(5):509-514.

Takano HK and Dayan FE 2020. Glufosinate‐ammonium: a review of the current state of knowledge. Pest Manage Sci 76 (12), 3911-3925

Mendes RR, Takano HK, Leal JF, Souza AS, Morran S, Oliveira RS Jr., Adegas FS, Gaines TA and Dayan FE 2020. Evolution of EPSPS double mutation imparting glyphosate resistance in wild poinsettia (Euphorbia heterophylla L.). PloS ONE 15 (9), e0238818.

Mendes RR, Takano HK, Oliveira Jr.RS, Adegas FS, Gaines TA, Dayan FE 2020. A Trp574Leu target-site mutation confers imazamox resistance in multiple herbicide-resistant wild poinsettia populations from Brazil. Agronomy 10 (8), 1057.

Mendes RR, Takano HK, Adegas FS, Oliveira RS, Gaines TA, Dayan FE 2020 Arg-128-Leu target-site mutation in PPO2 evolves in wild poinsettia (Euphorbia heterophylla) with cross-resistance to PPO-inhibiting herbicides. Weed Science 68:437-44.

Korres NE and Dayan FE 2020. Effects on climate change on crops and weeds. The need for climate-smart adaptation paradigm. Outlooks on Pest Management 31(5) 210-215.

Rigon CAG, Gaines TA, KĂŒpper A, and Dayan FE 2020. Metabolism-based herbicide resistance, the major threat among the non-target site resistance mechanisms. Outlooks on Pest Management 31(4) 162-168.

Takano HK, Beffa R, Preston C, Westra P and Dayan FE 2020. A novel insight into the mode of action of glufosinate: how reactive oxygen species are formed. Photosynthesis Research 144:361–372.

Takano HK, Beffa R, Preston C, Westra P and Dayan FE 2020. Glufosinate enhances the activity of protoporphyrinogen oxidase inhibitors. Weed Science 68(4): 324-332.

Gaines TA, Duke SO, Morran S, Rigon CAG, Tranel PJ, KĂŒpper A and Dayan FE 2020. Mechanisms of evolved herbicide resistance. J Biol Chem 295:10307-10330.

Owens DK, Bajsa-Hirschel J, Duke SO, Carbonari CA, Gomes GLGC, Asolkar R, Boddy L and Dayan FE 2020. The contribution of romidepsin to the herbicidal activity of Burkholderia rinojensis biopesticide. J Nat Prod 83(4): 843-851.

Takano HK, Beffa RS, Preston C, Westra P, Dayan FE 2020. Physiological factors affecting uptake and translocation of glufosinate. Journal of Agricultural and Food Chemistry 68:3026-3032.

Takano HK, Fernandes VNA, Adegas FS, Oliveira RS Jr, Westra P, Gaines TA and Dayan FE. 2020. A novel TIPT double mutation in EPSPS conferring glyphosate resistance in tetraploid Bidens subalternans. Pest Management Science 76: 95–102.

Busi R, Dayan FE, Francis I, Goggin D, Lercher J, Porri A, Powles SB, Sun C, and Beckie HJ. 2020.  Cinmethylin controls multiple herbicide-resistant Lolium rigidum and its wheat selectivity is P450-based. Pest Management Science, 76(8):2601-2608.

Carbonari CA, Alves de Mattos AK, Santos de Brito IPF, Velini ED and Dayan FE 2020. Impact of Green cane harvesting on pest management in sugarcane. Outlooks on Pest Management 31(2), 64-73.
Takano HK, Melo MSC, Ovejero RFL, Westra PH, Gaines TA, Dayan FE 2020. Trp2027Cys mutation evolves in Digitaria insularis with cross-resistance to ACCase inhibitors. Pestic Biochem Physiol 164:1-6.

Dayan FE. 2019. Current status and future prospects in herbicide discovery. Plants, 8, 341.

Clark SL, da Silva PV, Dayan FE, Nissen SJ and Sebastian DJ 2019. The influence of winter annual grass litter on herbicide availability.  Weed Science 67: 702–709.

Dayan FE, Barker A, Dayan LC and Ravet K 2019. The role of antioxidants in the protection of plants against inhibitors of protoporphyrinogen oxidase. Reactive Oxygen Species (ROS) 7(19): 55–63.

Keshtkar E, Abdolshahi R, Sasanfar H, Zand E, Beffa R, Dayan FE and Per Kudsk P 2019. Assessing fitness costs from a herbicide-resistance management perspective: A review and insight. Weed Science 67, 137-148.

Lebecque S, Lins L, Dayan FE, Fauconnier M-L, Deleu M 2019. Interactions between natural herbicides and lipid bilayers mimicking the plant plasma membrane. Frontiers in Plant Science 10:329 doi: 10.3389/fpls.2019.00329.

Nandula VK, Riechers DE, Ferhatoglu Y, Barrett M, Duke SO, Dayan FE, Goldberg-Cavalleri A, TĂ©tard-Jones C, Wortley DJ, Onkokesung N, Brazier-Hicks M, Edwards R, Gaines TA, Iwakami S, Jugulam M and Ma R 2019. Herbicide metabolism: Crop selectivity, bioactivation, weed resistance, and regulation. Weed Science 67, 149-175.

Barker A and Dayan FE 2019. The fate of glyphosate in Roundup Ready sugarbeet (Beta vulgaris). Journal of Agricultural and Food Chemistry 67 (7), 2061–206.

Romdhane S, Devers-Lamrani M, Beguet J, Bertrand C, Calvayrac C, Salvia M-V, Jrad AB, Dayan FE, Spor A, Barthelmebs L and Martin-Laurent F 2019. Assessment of the ecotoxicological impact of natural and synthetic ÎČ-triketone herbicides on the diversity and activity of the soil bacterial community using omic approaches. Science of the Total Environment 651:241-249.

Duke SO, Stidham MA and Dayan FE 2019. A novel genomic approach to herbicide and herbicide mode of action discovery. Pest Management Science 75:314–317.

Brunharo CACG, Takano HK, Mallory-Smith CA, Dayan FE, Hanson BD 2019. Role of glutamine synthetase isogenes and herbicide metabolism in the mechanism of resistance to glufosinate in Lolium perenne L. spp. multiflorum biotypes from Oregon. J. Agric. Food Chem. J. Agric. Food Chem. 67:8431-8440.

Dayan FE, Haesaert G, Van Leeuwen T, Holden-Dye L, Crossthwaite A, Nauen R 2019. Pesticides modes of action and resistance: A perspective from the 2019 IUPAC congress. Outlooks Pest Manag. 30, 157-163.

Takano HK, Beffa R, Preston C, Westra P, Dayan FE 2019. Reactive oxygen species trigger the fast action of glufosinate. Planta, 249, 1837–1849.

Takano HK, Mendes RR, Scoz LB, Lopez Ovejero RF, Constantin J, Gaines TA, Westra P, Dayan FE, Oliveira Jr. RS 2019. Proline 106 EPSPS mutation imparting glyphosate resistance in goosegrass (Eleusine indica) emerges in South America. Weed Sci. 67, 48-56.

Takano HK, Patterson EL, Nissen SJ, Dayan FE, Gaines TA 2019. Predicting herbicide movement across semi-permeable membranes using three phase partitioning. Pestic. Biochem. Physiol. 159: 22-26.

Oliveira, M. C., Gaines, T. D., Dayan, F. E., Patterson, E., Jhala, A. and Knezevic, S. 2017. Reversing resistance to tembotrione in the Amaranthus tuberculatus (syn. rudis) from Nebraska with cytochrome P450 inhibitors. Pest Management Science. Available online.

Dayan, F.E., Barker, A. and Tranel, P.J., 2017. Origins and Structure of Chloroplastic and Mitochondrial Plant Protoporphyrinogen Oxidases: Implications for Evolution of Herbicide Resistance. Pest Management Science. Available online

Carbonari, C., Latorre, D. O., Gomes, G. L. G. C., Velini, E. D., Owens, D. K., Pan, Z., and Dayan, F. E. 2016. Resistance to glufosinate is proportional to phosphinothricin acetyltransferase expression and activity in LibertyLinkÂź and WideStrikeÂź cotton. Planta 243:925-933.

Corniani, N., Velini, E. D., Silva, F. M. L., Nanayakkara, N. P. D., Witschel, M. and Dayan, F. E. Novel bioassay for the discovery of inhibitors of the 2-C-Methyl-d-erythritol 4-phosphate (MEP) and terpenoid pathways leading to carotenoid biosynthesis. PLoS ONE 9: e103704.

CorrĂȘa, E. A., Dayan, F. E., Owens, D. K., Rimando, A. M., and Duke, S. O. 2016. Glyphosate-resistant and conventional canola (Brassica napus L.) responses to glyphosate and aminomethylphosphonic acid (AMPA) treatment. Journal of Agricultural and Food Chemistry 64:3508-3513.

Dayan, F. E., Owens, D. K., Corniani, N., Silva, F. M. L., Watson, S. B., Howell, J. and Shaner, D. L. 2015. Biochemical markers and enzyme assays for herbicide mode of action and resistance studies. Weed Science.  63, 23-63.

Dayan, F. E., Owens, D. K., Tranel, P. J., Preston, C. and Duke, S. O. 2014. Evolution of resistance to phytoene desaturase and protoporphyrinogen oxidase inhibitors – State of knowledge. Pest Management Science, 70: 1358-1366.

Garcia, A., Alarcon-Reverte, R., Watson, S. B., Abdallah, I., Dayan, F. E., Fischer, A. 2014. Concerted action of target-site mutations and high EPSPS activity in glyphosate-resistant junglerice (Echinochloa colona) from California. Pest Management Science, 71: 996-1007.

Maroli, A. S., Nandula, V. K., Dayan, F. E., Duke, S. O., Gerard, P., Tharayil, N. 2015. Metabolic profiling and enzyme analyses indicate a potential role of antioxidant systems in complementing glyphosate resistance in an Amaranthus palmeri Journal of Agricultural and Food Chemistry, 63:9199-9209.

Ribeiro, D. N., Nandula, V. K., Dayan, F. E., Rimando, A. M., Duke, S. O., Reddy, K. N., and Shaw. D. R. 2015. Possible glyphosate resistance mechanisms in pitted morningglory (Ipomoea lacunosa), Journal of Agricultural and Food Chemistry, 63:23-63.

Ribeiro, N. D., Pan, Z., Duke, S. O., Nandula, V. K., Baldwin, B. S., Shaw, D. and Dayan, F. E. Involvement of facultative apomixis in inheritance of EPSPS gene amplification in glyphosate-resistant Amaranthus palmeri.  Planta, 239:199-212.

Mentioned in

Salas, R. A., Scott, R. C., Dayan, F. E., and Burgos, N. R. 2015. EPSPS gene amplification in glyphosate-resistant in Italian ryegrass (Lolium perenne multiflorum) populations from Arkansas, United States. Journal of Agricultural and Food Chemistry, 63: 5885-5893.

Salas, R. A., Dayan, F. E., Pan, Z., Watson, S., Dickson, J., Scott, R. C., and Burgos, N. EPSPS gene amplification in glyphosate-resistant Italian ryegrass (Lolium perenne ssp multiflorum) from Arkansas, USA.  Pest Management Science, 68, 1223-1230.

Silva, F. M. L., Duke, S. O., Dayan, F. E. and Velini, E. D. 2016. Low doses of glyphosate change the response of soybean to subsequent glyphosate treatments. Weed Research 56:124-136.

Chemical Ecology and Natural Products

Pan, Z., Baerson, S. R., Wang, M., Bajsa‐Hirschel, J., Rimando, A. M., Wang, X., Nanayakkara, N. P. D., Noonan, B. P., Fromm, M. E., Dayan, F. E., Khan, I. A., and Duke, S. O. (2018). A cytochrome P450 CYP71 enzyme expressed in Sorghum bicolor root hair cells participates in the biosynthesis of the benzoquinone allelochemical sorgoleone. New Phytologist 218:616-629.

GƂąb, L., SowiƄski, J., Bough, R. and Dayan, F. E. 2017. Allelopathic potential of Sorghum bicolor (L.) Moench in weed control: A comprehensive review. Advances in Agronomy, 145:43-95.

Killeen, D. P., Larsen, L., Dayan, F. E., Gordon, K. C., Perry, N. B. and van Klink, J. W. 2016. Nortriketones: Antimicrobial trimethylated acylphloroglucinols from mānuka (Leptospermum scoparium). Journal of Natural Products 79:564-569

Cantrell, C. L., Dayan, F. E. and Duke, S. O. 2012. Natural products as sources for new pesticides. Journal of Natural Products, 75, 1231-1242.

Chen, X., Berim, A., Dayan. F. E., Gang, D. R. 2017. A (-)-Kolavenyl diphosphate synthase catalyzes the first committed step of salvinorin A biosynthesis in Salvia divinorum. Journal of Experimental Botany, 68:1109-1122.

Dayan, F. E., Owens, D. K., Watson, S. B., Asolkar, R. N. and Boddy, L. G. 2015. Sarmentine, a natural herbicide from Piper species with multiple herbicide mechanisms of action, Frontiers in Plant Science, 6. doi: 10.3389/fpls.2015.00222.

Dayan, F. E. and Duke, S. O. 2014. Natural compounds as next generation herbicides. Plant Physiology, 166:1090-1105. This article was selected as the lead article in this special issue of Plant Physiology.

Dayan, F. E., Owens, D. K. and Duke, S. O. 2012. Rationale for a natural products approach to herbicide discovery. Pest Management Science, 68, 519-528.

GƂąb, L., SowiƄski, J., Bough, R. and Dayan, F. E. 2017. Allelopathic potential of Sorghum bicolor (L.) Moench in weed control: A comprehensive review. Advances in Agronomy, in press.

Owens, D. K., Nanayakkara, N. P. D. and Dayan, F. E. In planta mechanism of action of leptospermone: Impact of its physico-chemical properties on uptake, translocation, and metabolism. Journal of Chemical Ecology. 39: 262-270.

Trivella, A., Stawingoga, M., Dayan, F. E., Cantrell, C. L., Mazellier, P., Richard, C. 2015. Photolysis of natural ÎČ-triketonic herbicides in water. Water Research, 78:28–36.

Patil, C., Calvayrac, C., Zhou, Y., Romdhane, S., Cooper, J.-F., Dayan, F. E. and Bertrand, C. 2016. Environmental Metabolic Footprinting: a novel application to study the impact of a natural and a synthetic ß-triketone herbicide in soil. Science of the Total Environment 566-567:552-558.

Rimando, A. M., Pan, Z., Polashock, J., Dayan, F. E., Mizuno, C., Snook, M. E., Liu, C.-J., and Baerson, S. R. 2012. In planta production of the highly potent resveratrol analogue pterostilbene via stilbene synthase and O-methyltransferase co-expression. Plant Biotechnology Journal, 10, 269-283.

Romdhane, S., Devers-Lamrani, M., Barthelmebs, L., Calvayrac, C., Bertrand, C., Cooper, J.-F., Dayan, F.E., Martin-Laurent, F. 2016. Ecotoxicological impact of the bioherbicide leptospermone on the microbial community of two arable soils. Frontiers in Microbiology 7:775.

Silva, F. M. L., Donega , M. A., Cerdeira, A. L., Corniani, N., Velini, E. D., Cantrell, C. L., Dayan, F. E., Coelho, M. N., Shea, K., Duke, S. O. 2014. Roots of the invasive species Carduus nutans and C. acanthoides L. produce large amounts of aplotaxene, a possible allelochemical. Journal of Chemical Ecology, 40:276-284.

Travaini, M. L., Sosa, G. M., Ceccarelli, E. A., Walter, H., Cantrell, C. L., Carrillo, N. J., Dayan, F. E., Meepagala, K. M. and Duke, S. O. Khellin and visnagin, furanochromones from Amni visnaga (L.) Lam., as potential bioherbicides. Journal of agricultural and food chemistry 64:9475-9487.

Uddin, M. R., Park, S. U., Dayan, F. E. and Pyon, J. Y. 2013. Herbicidal activity of formulated sorgoleone, a natural product of sorghum root exudate. Pesticide Management Science, 70:252-257.

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