|Huffaker, Alisa - University Of California|
|Schmelz, Eric - University Of California|
|Allen, Leon - Retired Ars Employee|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 8/11/2015
Publication Date: 8/11/2015
Citation: 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].
Technical Abstract: Elevated atmospheric carbon dioxide concentration ([CO2]) increased maize susceptibility to Fusarium verticillioides stalk rot. Even though the pathogen biomass accumulated to significantly higher levels at double ambient [CO2] (2x[CO2]), the projected [CO2] concentration to occur at the end of this century, the quantity of fumonisin mycotoxin contaminants were unaltered. Combined effects of [CO2] and drought on pathogen infection were contradictory; drought reduced F. verticillioides biomass in maize stalks at ambient [CO2] (1x[CO2]), but increased pathogen biomass in stems at 2x[CO2]. In the absence of the host plant, 2x[CO2] hindered F. verticillioides growth but enhanced fuminison production on media. The soluble carbohydrate, starch, protein, and fatty acid content of the maize stem tissues were not significantly altered by 2x[CO2]. However, in response to F. verticillioides infection, the accumulation of soluble carbohydrates, total proteins, fatty acids, 6-methoxy-2-benzoxazolinone, and phytoalexins was absent or reduced in maize plants at 2x[CO2]. Examination of early jasmonic acid (JA) levels in response to F. verticillioides infection, indicated that the phytohormone defense response maybe dampened at 2x[CO2]. There was a direct correlation between JA levels and the levels of defense metabolites, and an inverse correlation with pathogen proliferations. The attenuation of JA signaling and the reduction of fumonisin produced per unit F. verticillioides biomass are potentially a result of limited free fatty acid substrate for oxylipin biosynthesis. By stimulating the defense response prior to F. verticillioides infection, maize plants grown at 2x[CO2] were capable of restricting pathogen proliferation to comparable levels as maize at 1x[CO2]. The adaptation of new disease management strategies, such as priming, may be necessary to improve the production and safety of the future maize crop at higher [CO2].