Vaughan Martha M, Huffaker Alisa, Schmelz Eric A, Dafoe Nicole J, Christensen Shawn A, McAuslane Heather J, Alborn Hans T, Allen Leon Hartwell, Teal Peter E A
Mycotoxin Prevention and Applied Microbiology Research Unit, National Center for Agricultural Utilization Research, United States Department of Agriculture, Agricultural Research Service, 1815 N University St, Peoria, Illinois, 61604, United States of America.
Chemistry Research Unit, Center of Medical, Agricultural, and Veterinary Entomology, United States Department of Agriculture, Agricultural Research Service, 1600 SW 23rd Drive, Gainesville, Florida, 32608, United States of America.
PLoS One. 2016 Jul 13;11(7):e0159270. doi: 10.1371/journal.pone.0159270. eCollection 2016.
Changes in climate due to rising atmospheric carbon dioxide concentration ([CO2]) are predicted to intensify episodes of drought, but our understanding of how these combined conditions will influence crop-pathogen interactions is limited. We recently demonstrated that elevated [CO2] alone enhances maize susceptibility to the mycotoxigenic pathogen, Fusarium verticillioides (Fv) but fumonisin levels remain unaffected. In this study we show that maize simultaneously exposed to elevated [CO2] and drought are even more susceptible to Fv proliferation and also prone to higher levels of fumonisin contamination. Despite the increase in fumonisin levels, the amount of fumonisin produced in relation to pathogen biomass remained lower than corresponding plants grown at ambient [CO2]. Therefore, the increase in fumonisin contamination was likely due to even greater pathogen biomass rather than an increase in host-derived stimulants. Drought did not negate the compromising effects of elevated [CO2] on the accumulation of maize phytohormones and metabolites. However, since elevated [CO2] does not influence the drought-induced accumulation of abscisic acid (ABA) or root terpenoid phytoalexins, the effects elevated [CO2] are negated belowground, but the stifled defense response aboveground may be a consequence of resource redirection to the roots.
预计大气中二氧化碳浓度（[CO₂]）上升导致的气候变化会加剧干旱情况，但我们对这些综合条件如何影响作物与病原体相互作用的了解有限。我们最近证明，仅升高[CO₂]就会增强玉米对产毒真菌病原体轮枝镰孢菌（Fv）的易感性，但伏马菌素水平不受影响。在本研究中，我们表明同时暴露于升高的[CO₂]和干旱环境下的玉米对Fv增殖更易感，且更容易受到更高水平的伏马菌素污染。尽管伏马菌素水平有所增加，但相对于病原体生物量产生的伏马菌素量仍低于在环境[CO₂]条件下生长的相应植株。因此，伏马菌素污染的增加可能是由于病原体生物量增加更多，而非宿主来源刺激物的增加。干旱并未消除升高的[CO₂]对玉米植物激素和代谢产物积累的不利影响。然而，由于升高的[CO₂]不影响干旱诱导的脱落酸（ABA）或根部萜类植物抗毒素的积累，升高的[CO₂]的影响在地下被抵消，但地上防御反应受阻可能是资源重新导向根部的结果。
