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Planta

Title:		"Fungal and herbivore elicitation of the novel maize sesquiterpenoid, zealexin A4, is attenuated by elevated CO(2)"
Author(s):		Christensen SA; Huffaker A; Sims J; Hunter CT; Block A; Vaughan MM; Willett D; Romero M; Mylroie JE; Williams WP; Schmelz EA;
Address:		"Chemistry Research Unit, Center for Medical, Agricultural, and Veterinary Entomology, United States Department of Agriculture, Agricultural Research Service, Gainesville, FL, 32608, USA. shawn.christensen@ars.usda.gov. Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA, 92093-0380, USA. Department of Environmental Systems Science, ETH Zurich, 8092, Zurich, Switzerland. Chemistry Research Unit, Center for Medical, Agricultural, and Veterinary Entomology, United States Department of Agriculture, Agricultural Research Service, Gainesville, FL, 32608, USA. Mycotoxin Prevention and Applied Microbiology Research, United States Department of Agriculture, Agricultural Research Service, 1815 N. University St., Peoria, IL, 61604, USA. Bennett Aerospace, Engineer and Research Development Center, Vicksburg, MS, 39180, USA. Crop Science Research Laboratory, United States Department of Agriculture, Agricultural Research Service, Dorman Hall, Stone Blvd., Starkville, MS, 39762, USA. Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA, 92093-0380, USA. eschmelz@ucsd.edu"
Journal Title:		Planta
Year:		2018
Volume:		247
Issue:		4
Page Number:		863 - 873
DOI:		10.1007/s00425-017-2830-5
ISSN/ISBN:		1432-2048 (Electronic) 0032-0935 (Linking)
Abstract:		"Chemical isolation and NMR-based structure elucidation revealed a novel keto-acidic sesquiterpenoid, termed zealexin A4 (ZA4). ZA4 is elicited by pathogens and herbivory, but attenuated by heightened levels of CO (2) . The identification of the labdane-related diterpenoids, termed kauralexins and acidic sesquiterpenoids, termed zealexins, demonstrated the existence of at least ten novel stress-inducible maize metabolites with diverse antimicrobial activity. Despite these advances, the identity of co-occurring and predictably related analytes remains largely unexplored. In the current effort, we identify and characterize the first sesquiterpene keto acid derivative of beta-macrocarpene, named zealexin A4 (ZA4). Evaluation of diverse maize inbreds revealed that ZA4 is commonly produced in maize scutella during the first 14 days of seedling development; however, ZA4 production in the scutella was markedly reduced in seedlings grown in sterile soil. Elevated ZA4 production was observed in response to inoculation with adventitious fungal pathogens, such as Aspergillus flavus and Rhizopus microsporus, and a positive relationship between ZA4 production and expression of the predicted zealexin biosynthetic genes, terpene synthases 6 and 11 (Tps6 and Tps11), was observed. ZA4 exhibited significant antimicrobial activity against the mycotoxigenic pathogen A. flavus; however, ZA4 activity against R. microsporus was minimal, suggesting the potential of some fungi to detoxify ZA4. Significant induction of ZA4 production was also observed in response to infestation with the stem tunneling herbivore Ostrinia nubilalis. Examination of the interactive effects of elevated CO(2) (E-CO(2)) on both fungal and herbivore-elicited ZA4 production revealed significantly reduced levels of inducible ZA4 accumulation, consistent with a negative role for E-CO(2) on ZA4 production. Collectively, these results describe a novel beta-macrocarpene-derived antifungal defense in maize and expand the established diversity of zealexins that are differentially regulated in response to biotic/abiotic stress"
Keywords:		"Alkyl and Aryl Transferases/metabolism Anti-Infective Agents/metabolism Aspergillus flavus/metabolism Carbon Dioxide/pharmacology Gene Expression Regulation, Plant/drug effects Plant Immunity Rhizopus/metabolism Seedlings/metabolism Sesquiterpenes/*metabo;"
Notes:		"MedlineChristensen, Shawn A Huffaker, Alisa Sims, James Hunter, Charles T Block, Anna Vaughan, Martha M Willett, Denis Romero, Maritza Mylroie, J Erik Williams, W Paul Schmelz, Eric A eng 6036-21000-011-00D/USDA-ARS/ 1139329/National Science Foundation/ Germany 2017/12/21 Planta. 2018 Apr; 247(4):863-873. doi: 10.1007/s00425-017-2830-5"