title: Effects of elevated [CO2 ] on maize defence against mycotoxigenic Fusarium verticillioides.
abstract: Maize is by quantity the most important C4 cereal crop; however, future climate changes are expected to increase maize susceptibility to mycotoxigenic fungal pathogens and reduce productivity. While rising atmospheric [CO2 ] is a driving force behind the warmer temperatures and drought, which aggravate fungal disease and mycotoxin accumulation, our understanding of how elevated [CO2 ] will effect maize defences against such pathogens is limited. Here we report that elevated [CO2 ] increases maize susceptibility to Fusarium verticillioides proliferation, while mycotoxin levels are unaltered. Fumonisin production is not proportional to the increase in F. verticillioides biomass, and the amount of fumonisin produced per unit pathogen is reduced at elevated [CO2 ]. Following F. verticillioides stalk inoculation, the accumulation of sugars, free fatty acids, lipoxygenase (LOX) transcripts, phytohormones and downstream phytoalexins is dampened in maize grown at elevated [CO2 ]. The attenuation of maize 13-LOXs and jasmonic acid production correlates with reduced terpenoid phytoalexins and increased susceptibility. Furthermore, the attenuated induction of 9-LOXs, which have been suggested to stimulate mycotoxin biosynthesis, is consistent with reduced fumonisin per unit fungal biomass at elevated [CO2 ]. Our findings suggest that elevated [CO2 ] will compromise maize LOX-dependent signalling, which will influence the interactions between maize and mycotoxigenic fungi.
authors.affiliation: Chemistry Research Unit, Center of Medical, Agricultural, and Veterinary Entomology, U.S. Department of Agriculture, Agricultural Research Service, Gainesville, FL, 32608, USA.
authors.forename: Martha M
authors.initials: MM
authors.lastname: Vaughan
authors.forename: Alisa
authors.initials: A
authors.lastname: Huffaker
authors.forename: Eric A
authors.initials: EA
authors.lastname: Schmelz
authors.forename: Nicole J
authors.initials: NJ
authors.lastname: Dafoe
authors.forename: Shawn
authors.initials: S
authors.lastname: Christensen
authors.forename: James
authors.initials: J
authors.lastname: Sims
authors.forename: Vitor F
authors.initials: VF
authors.lastname: Martins
authors.forename: Jay
authors.initials: J
authors.lastname: Swerbilow
authors.forename: Maritza
authors.initials: M
authors.lastname: Romero
authors.forename: Hans T
authors.initials: HT
authors.lastname: Alborn
authors.forename: Leon Hartwell
authors.initials: LH
authors.lastname: Allen
authors.forename: Peter E A
authors.initials: PE
authors.lastname: Teal
mesh_terms: D002245:Carbon Dioxide / Q000494:pharmacology*; D003517:Cyclopentanes / Q000378:metabolism; D004198:Disease Susceptibility; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics; D005227:Fatty Acids / Q000378:metabolism; D005670:Fusarium / Q000187:drug effects / Q000502:physiology*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D009183:Mycotoxins / Q000633:toxicity*; D054883:Oxylipins / Q000378:metabolism; D010935:Plant Diseases / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018547:Plant Stems / Q000187:drug effects / Q000382:microbiology; D020156:Salicylic Acid / Q000378:metabolism; D012717:Sesquiterpenes / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects; D003313:Zea mays / Q000235:genetics / Q000254:growth & development / Q000276:immunology* / Q000382:microbiology*; D000094162:Phytoalexins
chemical_list: D003517:Cyclopentanes; D005227:Fatty Acids; D009183:Mycotoxins; D054883:Oxylipins; D010940:Plant Proteins; D012717:Sesquiterpenes; D002245:Carbon Dioxide; C011006:jasmonic acid; D020156:Salicylic Acid; D000094162:Phytoalexins
keywords: C4 crop; climate change; fumonisin; jasmonic acid; lipoxigenase; mycotoxin; phytoalexins