Effects of elevated [CO2] on maize defence against mycotoxigenic Fusarium verticillioides

Authors

  • MARTHA M. VAUGHAN,

    Corresponding author
    1. Chemistry Research Unit, Center of Medical, Agricultural, and Veterinary Entomology, U.S. Department of Agriculture, Agricultural Research Service, Gainesville, FL, USA
    • Correspondence: M. M. Vaughan, BFP&M, NCAUR, USDA, 1815 N. University Street, Peoria, IL 61604, USA. E-mail: Martha.vaughan@ars.usda.gov

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  • ALISA HUFFAKER,

    1. Chemistry Research Unit, Center of Medical, Agricultural, and Veterinary Entomology, U.S. Department of Agriculture, Agricultural Research Service, Gainesville, FL, USA
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  • ERIC A. SCHMELZ,

    1. Chemistry Research Unit, Center of Medical, Agricultural, and Veterinary Entomology, U.S. Department of Agriculture, Agricultural Research Service, Gainesville, FL, USA
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  • NICOLE J. DAFOE,

    1. Chemistry Research Unit, Center of Medical, Agricultural, and Veterinary Entomology, U.S. Department of Agriculture, Agricultural Research Service, Gainesville, FL, USA
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  • SHAWN CHRISTENSEN,

    1. Chemistry Research Unit, Center of Medical, Agricultural, and Veterinary Entomology, U.S. Department of Agriculture, Agricultural Research Service, Gainesville, FL, USA
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  • JAMES SIMS,

    1. Chemistry Research Unit, Center of Medical, Agricultural, and Veterinary Entomology, U.S. Department of Agriculture, Agricultural Research Service, Gainesville, FL, USA
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  • VITOR F. MARTINS,

    1. Department of Biochemistry, University of Florida, Gainesville, FL, USA
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  • JAY SWERBILOW,

    1. Department of Biochemistry, University of Florida, Gainesville, FL, USA
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  • MARITZA ROMERO,

    1. Chemistry Research Unit, Center of Medical, Agricultural, and Veterinary Entomology, U.S. Department of Agriculture, Agricultural Research Service, Gainesville, FL, USA
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  • HANS T. ALBORN,

    1. Chemistry Research Unit, Center of Medical, Agricultural, and Veterinary Entomology, U.S. Department of Agriculture, Agricultural Research Service, Gainesville, FL, USA
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  • LEON HARTWELL ALLEN,

    1. Chemistry Research Unit, Center of Medical, Agricultural, and Veterinary Entomology, U.S. Department of Agriculture, Agricultural Research Service, Gainesville, FL, USA
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  • PETER E. A. TEAL

    1. Chemistry Research Unit, Center of Medical, Agricultural, and Veterinary Entomology, U.S. Department of Agriculture, Agricultural Research Service, Gainesville, FL, USA
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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.

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