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ARS Home » Southeast Area » Gainesville, Florida » Center for Medical, Agricultural and Veterinary Entomology » Chemistry Research » People & Locations » Shawn Christensen

Shawn Christensen
Chemistry Research
Research Plant Physiologist

Phone: (352) 374-5739
Fax: (352) 374-5707

1700 S.W. 23RD DR
GAINESVILLE, FL 32608
Projects
Molecular and Biochemical Characterization of Biotic and Abiotic Stress on Plant Defense Responses in Maize
In-House Appropriated (D)
  Accession Number: 434496
The Identification and Characterization of Southern Leaf Blight Resistance Genes
Non-Assistance Cooperative Agreement (S)
  Accession Number: 436214

Publications (Clicking on the reprint icon Reprint Icon will take you to the publication reprint.)
Fusarium verticillioides induces maize-derived ethylene to promote virulence by engaging fungal G-protein signaling Reprint Icon - (Peer Reviewed Journal)
Y-S. Park; E.J. Borrego; X. Gao, S.A. Christensen; E. Schmelz; A. Lanubile; D.A. Drab; W. Cody; H. Yan; W-B. Shim; M.V. Kolomiets. 2021. Fusarium verticillioides induces maize-derived ethylene to promote virulence by engaging fungal G-protein signaling. Molecular Plant Microbe Interactions https//doi.org/10.1094/MPMI-09-20-0250-R
Analysis of the transcriptomic, metabolomic, and gene regulatory responses to Puccinia sorghi in maize Reprint Icon - (Peer Reviewed Journal)
Kim, S., Karre, S., Choi, H., Christensen, S.A., Wang, G., Jo, Y., Cho, W., Balint Kurti, P.J. 2021. Analysis of the transcriptomic, metabolomic, and gene regulatory responses to Puccinia sorghi in maize. Molecular Plant Pathology. https://doi.org/10.1111/mpp.13040.
Brachypodium PHENYLALANINE AMMONIA LYASE (PAL) promotes antiviral defenses against Panicum mosaic virus and its satellites. Reprint Icon - (Peer Reviewed Journal)
Plant, S.R.; Irigoyen, S.; Liu, J.; Bedre, R.H.; Christensen, S.A.; Schmelz, E.A.; Sedbrook, J.; Scholthof, K.G.; Mandadi, K.K. 2021. Brachypodium phenylalanine ammonia lyase (PAL) promotes antiviral defenses against Panicum mosaic virus and its satellites. mBio. 12:e03518-20. https//doi.org/10.1128/mBio.03518-20
The 13-lipoxygenase MSD2 and the w-3 fatty acid desaturase MSD3 impact Spodoptera frugiperda resistance in Sorghum Reprint Icon - (Peer Reviewed Journal)
Block, A.K.; Xin, Z; and Christensen, S.A. 2020 The 13-lipoxygenase MSD2 and the w-3 fatty acid desaturase MSD3 impact Spodoptera frugiperda resistance in Sorghum. Planta 252:62 https://doi:10.1007/s00425-020-03475-2
Genetic elucidation of interconnected antibiotic pathways mediating maize innate immunity Reprint Icon - (Peer Reviewed Journal)
Ding, Y., Weckwerth, P.R., Poretsky, E., Murphy, K.M., Sims, J., Saldivar, E., Christensen, S.A., Char, S., Yang, B., Tong, A., Shen, Z., Kremling, K.A., Buckler IV, E.S., Kono, T., Nelson, D.R., Bohlmann, J., Bakker, M.G., Vaughan, M.M., Khalil, A.S., Betsiashvili, M., Briggs, S.P., Zerbe, P., Schmelz, E.A., Huffaker, A. 2020. Genetic elucidation of interconnected antibiotic pathways mediating maize innate immunity. Nature Plants. (6):1375-1388. https://doi.org/10.1038/s41477-020-00787-9.
Genetic elucidation of complex biochemical traits in crop innate immunity - (Peer Reviewed Journal)
Plant defense chemicals against insect pests Reprint Icon - (Peer Reviewed Journal)
Yactayo Chang, J.P.; Tang, H.V.; Mendoza, J.S.; Christensen, S.A.; Block, A.K. 2020. Plant defense chemicals against insect pests. Agronomy. 10:1156. 2020 https://doi.org/10.3390/agronomy10081156.
Genetic elucidation of complex biochemical traits mediating maize innate immunity Reprint Icon ()
Ding, Y., Weckwerth, P., Poretsky, E., Murphy, K., Sims, J., Saldivar, E., Christensen, S.A., Char, S., Yang, B., Tong, A., Shen, Z., Kremling, K., Buckler IV, E.S., Kono, T., Nelson, D., Bohlmann, J., Bakker, M.G., Vaughan, M.M., Khalil, A., Betsiashvili, M., Briggs, S., Zerbe, P., Schmelz, E., Huffaker, A. 2020. Genetic elucidation of complex biochemical traits mediating maize innate immunity. bioRxiv. https://doi.org/10.1101/2020.03.04.977355.
Green Leaf volatiles and jasmonic acid enhance susceptibility to anthracnose diseases caused by Colletotrichum graminicola in maize Reprint Icon - (Peer Reviewed Journal)
Gorman, Z., Christensen, S.A., Yan, Y., Ye, Y., Borrego, E., Kolomiets, M.V. 2020. Green Leaf volatiles and jasmonic acid enhance susceptibility to anthracnose diseases caused by Colletotrichum graminicola in maize. Molecular Plant Pathology. 21(5):702-715. https://doi.org/10.1111/mpp.12924.
Setaria viridis as a model for translational genetic studies of jasmonic acid-responsive insect defenses in Zea mays Reprint Icon - (Peer Reviewed Journal)
Hunter III, C.T., Block, A.K., Christensen, S.A., Li, Q., Rering, C.C., Alborn, H.T. 2020. Setaria viridis as a model for translational genetic studies of jasmonic acid-responsive insect defenses in Zea mays. Plant Science. 291, February 2020, 110329. https://doi.org/10.1016/j.plantsci.2019.110329.
Fertility of pedicellate spikelets in sorghum is controlled by a jasmonic acid regulatory module Reprint Icon - (Peer Reviewed Journal)
Gladman, N.P., Jiao, Y., Lee, Y., Zhang, L., Chopra, R., Regulski, M., Burow, G.B., Hayes, C.M., Christensen, S.A., Dampanaboina, L., Chen, J., Burke, J.J., Ware, D., Xin, Z. 2019. Fertility of pedicellate spikelets in sorghum is controlled by a jasmonic acid regulatory module. Nature Plants. 20(19). https://doi.org/10.3390/ijms20194951.
Fighting on two fronts: Elevated insect resistance in flooded maize Reprint Icon - (Peer Reviewed Journal)
Block, A.K., Hunter III, C.T., Sattler, S.E., Rering, C.C., Mcdonald, S., Basset, G.J., Christensen, S.A. 2019. Fighting on two fronts: Elevated insect resistance in flooded maize. Plant Cell and Environment. https://doi.org/10.1111/pce.13642.
Genetic elucidation of interconnected antibiotic pathways mediating maize innate immunity Reprint Icon - (Peer Reviewed Journal)
Ding, Y.; Murphy, K.M.; Poretsky, E.; Mafu, S.; Yang, B.; Char, S.; Christensen, S.A.; Saldivar, E.; Wu, M.; Wang, Q.; Ji, L.; Schmitz, R.J.; Kremling, K.A.; Buckler, E.S.; Shen, Z.; Briggs, S.P.; Bohlmann, J.; Sher, A.; Castro-Falcon, G.; Hughes, C.C.; Huffaker, A.; Zerbe, P.; Schmelz, E.A. 2020. Genetic elucidation of interconnected antibiotic pathways mediating maize innate immunity. Nature Plants. 6(11):1375-1388. https://doi.org/10.1038/s41477-020-00787-9.
Multiple genes recruited from hormone pathways partition maize diterpenoid defences Reprint Icon - (Peer Reviewed Journal)
Ding, Y., Murphy, K., Poretsky, E., Mafu, S., Yang, B., Char, S., Christensen, S.A., Saldivar, E., Wu, M., Wang, Q., Ji, L., Schmitz, R., Kremling, K., Buckler IV, E.S., Shen, Z., Briggs, S., Bohlmann, J., Sher, A., Castro-Falcon, G., Hughes, C., Huffaker, A., Zerbe, P., Schmelz, E. 2019. Multiple genes recruited from hormone pathways partition maize diterpenoid defences. Nature Plants. https://doi.org/10.1038/s41477-019-0509-6.
A maize polygalacturonase functions as a suppressor of the hypersensitive response and programmed cell death in maize - (Peer Reviewed Journal)
He, Y., Christensen, S.A., Karre, S., Johal, G., Balint Kurti, P.J. 2019. A maize polygalacturonase functions as a suppressor of the hypersensitive response and programmed cell death in maize. Biomed Central (BMC) Plant Biology. 19:310.
Production and function of terpenoid defense compounds in maize (Zea mays) Reprint Icon ()
Block, A.K., Vaughan, M.M., Schmelz, E.A., Christensen, S.A. 2018. Production and function of terpenoid defense compounds in maize (Zea mays). Planta. https://doi.org/10.1007/s00425-018-2999-2.
Kauralexins and zealexins accumulate in sub-tropical maize lines and play a role in seedling resistance to Fusarium verticillioides Reprint Icon - (Peer Reviewed Journal)
Veenstra, A., Moola, N., Wighard, S., Korsman, J., Christensen, S.A., Rafudeen, M., Murray, S.L. 2018. Kauralexins and zealexins accumulate in sub-tropical maize lines and play a role in seedling resistance to Fusarium verticillioides. European Journal of Plant Pathology. 153:223-237. https://doi.org/10.1007/s10658-018-1557-x.
Interactions among plants, insects, and microbes: elucidation of inter-organismal chemical communications in agricultural ecology Reprint Icon - (Peer Reviewed Journal)
Beck, J.J., Alborn, H.T., Block, A.K., Christensen, S.A., Hunter III, C.T., Rering, C.C., Seidl-Adams, I., Stuhl, C.J., Torto, B., Tumlinson, J.H. 2018. Interactions among plants, insects, and microbes: elucidation of inter-organismal chemical communications in agricultural ecology. Journal of Agricultural and Food Chemistry. 66(26):6663-6674. doi:10.1021/acs.jafc.8b01763.
Exploring the metabolic variation between domesticated and wild tetraploid wheat genotypes in response to corn leaf aphid infestation Reprint Icon - (Peer Reviewed Journal)
Chandrasekhar, K., Shavit, R., Distefeld, A., Christensen, S.A., Tzin, V. 2018. Exploring the metabolic variation between domesticated and wild tetraploid wheat genotypes in response to corn leaf aphid infestation. Plant Signaling and Behavior. 13(6):1-5. https://doi.org/10.1080/15592324.2018.1486148.
Pesticides on the inside: Exploiting the natural chemical defenses of maize against insect and microbial pests Reprint Icon - (Peer Reviewed Journal)
Christensen, S.A., Hunter III, C.T., Block, A.K. 2018. Pesticides on the inside: Exploiting the natural chemical defenses of maize against insect and microbial pests. ACS Symposium Series. https://doi.org/10.1021/bk-2018-1294.ch006.
Contrasting insect attraction and herbivore-induced plant volatile production in maize Reprint Icon - (Peer Reviewed Journal)
Block, A.K., Hunter III, C.T., Rering, C.C., Christensen, S.A., Meagher Jr, R.L. 2018. Contrasting insect attraction and herbivore-induced plant volatile production in maize. Planta. doi:10.1007/s00425-018-2886-x.
Commercial hybrids and mutant genotypes reveal complex protective roles for inducible terpenoid defenses - (Peer Reviewed Journal)
Christensen, S.A., Sims, J., Vaughan, M.M., Hunter III, C.T., Block, A.K., Willett, D.S., Alborn, H.T., Huffaker, A., Schmelz, E.A. 2018. Commercial hybrids and mutant genotypes reveal complex protective roles for inducible terpenoid defenses. Journal of Experimental Botany. doi:10.1093/jxb/erx495.
Maize w3 disrupts homogentisate solanesyl transferase (ZmHst) and reveals a plastoquinone-9 independent path for phytoene desaturation and tocopherol accumulation in kernels - (Peer Reviewed Journal)
Hunter III, C.T., Saunders, J., Magallanes-Lundback, M., Christensen, S.A., Willett, D.S., Stinard, P.S., Li, Q., Lee, K., Dellapenna, D., Koch, K.E. 2018. Maize w3 disrupts homogentisate solanesyl transferase (ZmHst) and reveals a plastoquinone-9 independent path for phytoene desaturation and tocopherol accumulation in kernels. Plant Journal. doi:10.1111/tpj.13821.
Herbivore derived fatty acid-amides elicit reactive oxygen species burst in plants - (Peer Reviewed Journal)
Block, A.K., Christensen, S.A., Hunter III, C.T., Alborn, H.T. 2017. Herbivore derived fatty acid-amides elicit reactive oxygen species burst in plants. Journal of Experimental Botany. doi:10.1093/jxb/erx449.
Fungal and herbivore elicitation of a newly identified maize sesquiterpenoid, zealexin A4, is constrained by abiotic stress Reprint Icon - (Peer Reviewed Journal)
Christensen, S.A., Huffaker, A., Sims, J., Hunter III, C.T., Block, A.K., Vaughan, M.M., Willett, D.S., Mylroie, E., Williams, P.C., Schmelz, E.A. 2017. Fungal and herbivore elicitation of a newly identified maize sesquiterpenoid, zealexin A4, is constrained by abiotic stress. Planta. 247(4):863-873. https://doi.org/10.1007/s00425-017-2830-5.
RNA-Seq analysis of resistant and susceptible sub-tropical maize lines reveals a role for kauralexins in resistance to grey leaf spot disease, caused by Cercospora zeina - (Peer Reviewed Journal)
Meyer, J., Berger, D.K., Christensen, S.A., Murray, S.L. 2017. RNA-Seq analysis of resistant and susceptible sub-tropical maize lines reveals a role for kauralexins in resistance to grey leaf spot disease, caused by Cercospora zeina. Biomed Central (BMC) Plant Biology. 17(1):197.
Rapid defense responses in maize leaves induced by Spodoptera exigua caterpillar feeding - (Peer Reviewed Journal)
Tzin, V., Hojo, Y., Strickler, S.R., Bartsch, L.J., Archer, C.M., Ahern, K.R., Shaoqun, Z., Christensen, S.A., Galis, I., Mueller, L.A., Jander, G. 2017. Rapid defense responses in maize leaves induced by Spodoptera exigua caterpillar feeding. Journal of Experimental Botany. 68(16):4709-4723.
The effects of climate change associated abiotic stresses on maize phytochemical defenses ()
Vaughan, M.M., Block, A., Christensen, S., Allen, L.H., Schmelz, E.A. 2017. The effects of climate change associated abiotic stresses on maize phytochemical defenses. Phytochemistry Reviews. doi: 10.1007/s11101-017-9508-2.
Elevated carbon dioxide reduces emission of herbivore induced volatiles in Zea mays - (Peer Reviewed Journal)
Block, A.K., Vaughan, M.M., Christensen, S.A., Alborn, H.T., Tumlinson, J.H. 2017. Elevated carbon dioxide reduces emission of herbivore induced volatiles in Zea mays. Plant Cell and Environment. doi:10.1111/pce.12976.
Seteria viridis as a model for pathogen resistance in the Poaceae - (Abstract Only)
Reduced stomatal conductance in plants grown under elevated carbon dioxide leads to lower emission of herbivore induced volatiles. - (Abstract Only)
Systems genetics reveals a transcriptional network associated with susceptibility in the maize-grey leaf spot pathosystem - (Peer Reviewed Journal)
Christie, N., Myburg, A.A., Joubert, F., Murray, S.L., Carstens, M., Lin, Y., Meyer, J., Crampton, B.G., Christensen, S.A., Ntuli, J.F., Wighard, S.S., Van De Peer, Y., Berger, D.K. 2017. Systems genetics reveals a transcriptional network associated with susceptibility in the maize-grey leaf spot pathosystem. Plant Journal. 89(4):746–763. doi:10.1111/tpj.13419.
Interactive effects of elevated [CO2] and drought on the maize phytochemical defense response against mycotoxigenic Fusarium verticillioides Reprint Icon - (Peer Reviewed Journal)
Vaughan, M.M., Huffaker, A., Schmelz, E.A., Dafoe, N.J., Christensen, S.A., McAuslane, H.J., Alborn, H.T., Allen, L.H., Teal, P.E.A. 2016. Interactive effects of elevated [CO2] and drought on the maize phytochemical defense response against mycotoxigenic Fusarium verticillioides. PLoS One. 11(7):e0159270. doi: 10.1371/journal.pone.0159270.
Maize terpenoid phytoalexins function in resistance against both abiotic and biotic stress - (Abstract Only)
Vaughan, M.M., Christensen, S.A., Schmelz, E.A., Huffaker, A., McAuslane, H., Alborn, H.T., Allen, L.H., Teal, P.E. 2016. Maize terpenoid phytoalexins function in resistance against both abiotic and biotic stress [abstract].
Maize death acids, 9-lipoxygenase derived cyclopente(a)nones, display activity as cytotoxic phytoalexins and transcriptional mediators - (Abstract Only)
Maize pathogens suppress inducible phytoalexin production to thwart innate plant immunity - (Abstract Only)
Maize white seedling 3 results from disruption of homogentisate solanesyl transferase - (Abstract Only)
A maize death acid, 10-oxo-11-phytoenoic acid, is the predominant cyclopentenone signal present during multiple stress and developmental conditions - (Peer Reviewed Journal)
Christensen, S.A., Huffaker, A., Hunter III, C.T., Alborn, H.T., Schmelz, E. 2016. A maize death acid, 10-oxo-11-phytoenoic acid, is the predominant cyclopentenone signal present during multiple stress and developmental conditions. Plant Signaling and Behavior. 11(2):e1120395.
Genetic mapping shows intraspecific variation and transgressive segregation for caterpillar-induced aphid resistance in maize - (Peer Reviewed Journal)
Tzin, V., Lindsay, P.L., Christensen, S.A., Meihls, L.N., Blue, L.B., Jander, G. 2015. Genetic mapping shows intraspecific variation and transgressive segregation for caterpillar-induced aphid resistance in maize. Molecular Ecology. 24(22):5739-5750.
Climate change and crop phytochemical defenses: Potential implications for food security and food safety - (Abstract Only)
Vaughan, M.M., Huffaker, A., Schmelz, E.A., Christensen, S.A., Allen, L.H., Teal, P.E. 2015. Climate change and crop phytochemical defenses: Potential implications for food security and food safety [abstract].
Maize death acids, 9-lipoxygenase-derived cyclopente(a)nones display activity as cytotoxic phytoalexins and transcriptional mediators - (Peer Reviewed Journal)
Christensen, S.A., Huffaker, A., Kaplan, F., Sims, J.W., Ziemann, S., Doehlemann, G., Ji, L., Schmitz, R.J., Kolomiets, M.V., Alborn, H.T., Mori, N., Jander, G., Ni, X., Sartor, R.C., Byers, S.O., Abdo, Z., Schmelz, E.A. 2015. Maize death acids, 9-lipoxygenase-derived cyclopente(a)nones display activity as cytotoxic phytoalexins and transcriptional mediators. Proceedings of the National Academy of Sciences. 112(36):11407-11412.
The maize death acids, 10-oxo-11-phytoenoic acid and derivatives, demonstrate specificity in jasmonate-related signaling and defense - (Abstract Only)
Accumulation of terpenoid phytoalexins in maize roots is associated with drought tolerance Reprint Icon - (Peer Reviewed Journal)
Vaughan, M.M., Christensen, S., Schmelz, E.A., Huffaker, A., McAuslane, H.J., Alborn, H.T., Romero, M., Allen, L.H., Teal, P.E.A. 2015. Accumulation of terpenoid phytoalexins in maize roots is associated with drought tolerance. Plant, Cell and Environment. 38:2195–2207.
Role of plant elicitor peptides and phytoalexins in enhancing maize resistance to Aspergillus flavus infection - (Abstract Only)
Isolation and structural elucidation of acidic terpenoid phytoalexins in maize and their interactions with Aspergillus flavus - (Abstract Only)
The novel monocot-specific 9-lipoxygenase, ZmLOX12 is required to mount an effective jasmonate-mediated defense against Fusarium verticillioides in maize - (Peer Reviewed Journal)
Christensen, S.A., Nemchenko, A., Park, Y., Borrego, E., Huang, P., Schmelz, E.A., Kunze, S., Feussner, I., Yalpani, N., Meeley, R., Kolomiets, M.V. 2014. The novel monocot-specific 9-lipoxygenase, ZmLOX12 is required to mount an effective jasmonate-mediated defense against Fusarium verticillioides in maize. Molecular Plant-Microbe Interactions. 24(11):1263-1276.
Effects of elevated [CO2] on maize defense against mycotoxigenic Fusarium verticillioides - (Abstract Only)
Vaughan, M.M., Huffaker, A., Schmelz, E.A., Dafoe, N.J., Christensen, S.A., Sims, J.W., Martins, V.F., Swerbilow, J., Romero, M.I., Alborn, H.T., Allen, L.H., Teal, P.E. 2014. Effects of elevated [CO2] on maize defense against mycotoxigenic Fusarium verticillioides [abstract].
Effects of elevated CO2 on maize defense against mycotoxigenic Fusarium verticillioides Reprint Icon - (Peer Reviewed Journal)
Vaughan, M.M., Huffaker, A., Schmelz, E.A., Dafoe, N.J., Christensen, S.A., Sims, J.W., Martins, V.F., Swerbilow, J.C., Romero, M.I., Alborn, H.T., Allen Jr, L.H., Teal, P.E. 2014. Effects of elevated CO2 on maize defense against mycotoxigenic Fusarium verticillioides. Plant Cell and Environment. doi: 10.1111/pce.12337.
Biosynthesis, elicitation and roles of monocot terpenoid phytoalexins ()
Schmelz, E.A., Huffaker, A., Sims, J.W., Christensen, S.A., Lu, X., Okada, K., Peters, R. 2014. Biosynthesis, elicitation and roles of monocot terpenoid phytoalexins. Plant Journal. 79:659-678.
Two closely related members of Arabidopsis 13-LOXs, LOX3 and LOX4, reveal distinct functions in response to plantparasitic nematode infection - (Peer Reviewed Journal)
Ozalvo, R., Cabrera, J., Escobar, C., Christensen, S.A., Borrego, E.J., Kolomiets, M.V., Castresana, C., Iberkleid, I., Horowitz, S.B. 2014. Two closely related members of Arabidopsis 13-LOXs, LOX3 and LOX4, reveal distinct functions in response to plantparasitic nematode infection. Molecular Plant Pathology. 15(4):319-332.
Seed treatment with live or dead Fusarium verticillioides equivalently reduces the severity of subsequent stalk rot - (Peer Reviewed Journal)
Martins, V.F., Vaughan, M.M., Huffaker, A., Schmelz, E.A., Christensen, S.A., Sims, J.W., Benda, N.D., Swerbilow, J.C., Alborn, H.T., Teal, P.E. 2013. Seed treatment with live or dead Fusarium verticillioides equivalently reduces the severity of subsequent stalk rot. Journal of Phytopathology. 162(3):201-204.
Maize pathogens suppress inducible phytoalexin production to thwart innate plant immunity - (Abstract Only)
Isolation and identificaton of novel terpenoid phytoalexins in maize - (Abstract Only)
Maize kauralexins: insights into structure, function, and biosynthesis - (Abstract Only)
The maize lipoxygenase, ZmLOX10, mediates green leaf volatile, jasmonate, and herbivore-induced plant volatile production for defense against insect attack - (Peer Reviewed Journal)
Christensen, S.A., Nemchenko, A., Borrego, E., Murray, I., Sobhy, I.S., Bosak, L., Deblasio, S., Matthias, E., Christelle, R., Vaughn, K.A., Herrfurth, C., Tumlinson, J., Feussner, I., Jackson, D., Turlings, T., Engelberth, J., Nansen, C., Meeley, R., Kolomiets, M.V. 2013. The maize lipoxygenase, ZmLOX10, mediates green leaf volatile, jasmonate, and herbivore-induced plant volatile production for defense against insect attack. Plant Journal. 74:59-73.