Location: Natural Products Utilization Research
2018 Annual Report
Accomplishments
1. Completion of biochemical and genetic characterization of the sorgoleone biosynthetic pathway. ARS researchers at Oxford, Mississippi, goal of identifying and characterizing the genes and enzymes required for the biosynthesis of the potent bioherbicide sorgoleone is now completed with the characterization of a root-hair specific cytochrome P450 from S. bicolor genotype BTx623. The cytochrome P450 protein was determined to belong to the CYP71 enzyme subfamily and has been formally designated S. bicolor CYP71AM1. Biochemical characterization of recombinant CYP71AM1 using both yeast (S. cerevisiae) and a Nicotiana benthamiana transient expression system demonstrated that CYP71AM1 is capable of performing dihydroxylation on the proposed physiological substrate 3-methyl-5-pentadecatrienyl resorcinol, yielding dihydrosorgoleone. These results clearly demonstrate a role for CYP71AM1 in the biosynthesis of sorgoleone in Sorghum bicolor, and represent the first example of a cytochrome P450 enzyme capable of catalyzing a dihydroxylation reaction occurring on a resorcinolic ring structure. Previously, our research team successfully identified the fatty acid desaturases, alkylresorcinol synthases, and an O-methyltransferase participating in the sorgoleone biosynthetic pathway. The characterization of CYP71AM1 represents a highly significant milestone, as our research unit has now characterized the genes and enzymes required for all of the biosynthetic steps leading to the formation of dihydrosorgoleone, beginning with palmitoleoyl-CoA. With this accomplishment we now have the tools in hand to engineer the production of sorgoleone in other crop species, which could potentially lead to the generation of novel germplasm possessing enhanced resistance to weed competition, and potentially against other agronomic pests as well.
Review Publications
Heap, I., Duke, S.O. 2017. Overview of glyphosate-resistant weeds worldwide. Pest Management Science. 74:1040-1049. doi 10.1002/ps.4760.
Pan, Z., Baerson, S.R., Wang, M., Bajsa Hirschel, J.N., Rimando, A.M., Wang, X., Nanayakkara, N., Noonan, B.P., Fromm, M.E., Dayan, F.E., Khan, I., Duke, S.O. 2018. A cytochrome P450 CYP71 enzyme expressed in S. bicolor root hair cells participates in the biosynthesis of the benzoquinone allelochemical sorgoleone. New Phytologist. doi: 10.1111/nph.15037.
Belz, R.G., Duke, S.O. 2018. Predicting hormesis in mixtures of herbicidal compounds – where are we and how far can we go? Julius Kühn Archiv. 458:161-167.
Labruzzo, A., Cantrell, C.L., Carrubba, A., Ali, A., Wedge, D.E., Duke, S.O. 2018. Phytotoxic Lignans from Artemisia arborescens. Natural Product Communications. 13(3):237-240.
Lu, X., Zhang, J., Xu, M., Li, R., Liu, B., Rodriguez-Romero, J., Luo, D., Pan, Z., Baerson, S.R., Li, Z., Sesma, A., Yang, B., Peters, R.J. 2018. Inferring roles in defense from metabolic allocation of rice diterpenoids. The Plant Cell. 30:1119-1131.
Maroli, A.S., Nandula, V.K., Duke, S.O., Gerard, P., Tharayil, N. 2017. Comparative metabolomic analyses of two Ipomoea lacunosa biotypes with contrasting glyphosate tolerance elucidates glyphosate-induced differential perturbations in cellular physiology. Journal of Agricultural and Food Chemistry. (66):2027-2039.
Meepagala, K.M., Briscoe, W.E., Techen, N., Johnson, R.D., Clausen, B.M., Duke, S.O. 2017. Isolation of a phytotoxic isocoumarin from Diaporthe eres-infected Hedera helix (English Ivy) and synthesis of its phytotoxic analogs. Pest Management Science. 74:37-45.
Morimoto, M., Cantrell, C.L., Khan, S., Tekwani, B.L., Duke, S.O. 2017. Antimalarial and antileishmanial activities of phytophenolics and their synthetic analogues. Chemistry and Biodiversity. DOI: 10.1002/cbdv.201700324.
Sanchez-Moreiras, A.M., Pedrol, N., Duke, S.O. 2018. Influence of amino acids on the phytotoxicity of 2-benzoxazolinone on Lemna paucicostata. Journal of Allelochemical Interactions. 4(1):33-39.
Wang, R., Liu, S., Baerson, S.R., Qin, Z., Ma, Z., Su, Y., Zhang, J. 2018. Identification and functional analysis of a novel cytochrome P450 gene CYP9A105 associated with pyrethroid detoxification in Spondoptera exigua Hubner. International Journal of Molecular Sciences. 19:737.
Westwood, J.H., Charudattan, R., Duke, S.O., Finnimore, S.A., Marrone, P., Slaughter, D.C., Swanton, C., Zollinger, R. 2018. Weed management in 2050: Perspective on the future of weed science. Weed Science. 66:275-285. https://doi.org/10.1017/wsc.2017.78.
Carvalho, L.B., Duke, S.O., Alves, P. 2018. Physiological responses of Eucalyptus x urograndis to glyphosate are dependent on the genotype. Scientia Forestalis. 46(118): 177-187.
Duke, S.O. 2018. Interaction of chemical pesticides and their formulation ingredients with microbes associated with plants and plant pests. Journal of Agricultural and Food Chemistry. 66:7753-7561. DOI: 10.1021/acs.jafc.8b02316.
Duke, S.O., Pan, Z., Bajsa Hirschel, J.N., Sanchez-Moreiras, A.M., Vaughn, J.N. 2018. Use of omics methods to determine the mode of action of natural phytotoxins. American Chemical Society Symposium Series. 1294:33-46.
Seiber, J.N., Coats, J., Duke, S.O., Gross, A.D. 2018. Pest management with biopesticides. Frontiers of Agricultural Science and Engineering. 5(3):205-300. https://doi.org/10.15302/J-FASE-2018238.
Beck, J.J., Duke, S.O., Rering, C.C. 2018. Roles of natural products for biorational pesticides in agriculture. ACS Symposium Series. 1294:1-4. https://doi.org/10.1021/bk-2018-1294.ch001.
