Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/8/2016
Publication Date: 6/8/2016
Citation: Vaughan, M.M. 2016. Climate change and corn susceptibility to mycotoxins [abstract].
Technical Abstract: Maize is an essential part of the world’s grain supply, but climate change has the potential to increase maize susceptibility to mycotoxigenic fungal pathogens and reduce food security and safety. While rising atmospheric [CO2] is a driving force of climate change, our understanding of how elevated [CO2] will effect maize defenses against such pathogens remains limited. Here we report that growth at elevated [CO2] increased maize susceptibility to Fusarium verticillioides proliferation without impacting fumonisin mycotoxin levels. Since fumonisin production was not proportional to the increase in F. verticillioides biomass, the amount of fumonisin produced per unit pathogen was reduced at elevated [CO2]. In combination with drought, however, maize at elevated [CO2] was even more susceptible to F. verticillioides infection and also prone to higher levels of fumonisin contamination. The increase in fumonisin was due to greater pathogen biomass rather than an increase in host-derived stimulants suggesting that the addition of drought did not negate the compromising effects of elevated [CO2]. Following F. verticillioides stalk inoculation, the accumulation of sugars, free fatty acids, lipoxygenase (LOX) transcripts, phytohormones, and downstream phytoalexins were dampened in maize grown at elevated [CO2]. The attenuation of maize 13-LOXs and jasmonic acid production was correlated with reduced terpenoid phytoalexins and increased susceptibility. Furthermore, the attenuated induction of 9-LOXs, which can stimulate mycotoxin biosynthesis, was consistent with reduced fumonisin per unit fungal biomass at elevated [CO2]. Our findings suggest that elevated [CO2] will compromise maize LOX-dependent signaling which are known to regulate both maize chemical defenses and mycotoxin production of multiple fungal pathogens.