02425naa a2200265 a 450000100080000000500110000800800410001902400390006010000170009924501240011626000090024050001790024952013610042865000140178965300200180365300260182365300180184965300350186770000230190270000190192570000150194470000150195970000180197477301670199210628312022-03-15       2022    bl uuuu     u00u1 u    #d7 a10.6084/m9.figshare.c.58330042DOI1 aJOHNSON, S.N  aElevated atmospheric CO 2 changes defence allocation in wheat but herbivore resistance persists.h[electronic resource]  c2022  aArticle history: Received: 23 November 2021/Accepted: 14 January 2022. Electronic supplementary material is available online at https://doi.org/10.6084/m9.figshare.c.5833004.  aAbstract: Predicting how plants allocate to different anti-herbivore defences in response to elevated carbon dioxide (CO2) concentrations is important for understanding future patterns of crop susceptibility to herbivory. Theories of defence allocation, especially in the context of environmental change, largely overlook the role of silicon (Si), despite it being the major anti-herbivore defence in the Poaceae. We demonstrated that elevated levels of atmospheric CO2 (e[CO2]) promoted plant growth by 33% and caused wheat (Triticum aestivum) to switch from Si (?19%) to phenolic (+44%) defences. Despite the lower levels of Si under e[CO2], resistance to the global pest Helicoverpa armigera persisted; relative growth rates (RGRs) were reduced by at least 33% on Si-supplied plants, irrespective of CO2 levels. RGR was negatively correlated with leaf Si concentrations. Mandible wear was c. 30% higher when feeding on Si-supplemented plants compared to those feeding on plants with no Si supply. We conclude that higher carbon availability under e[CO2] reduces silicification and causes wheat to increase concentrations of phenolics. However, Si supply, at all levels, suppressed the growth of H. armigera under both CO2 regimes, suggesting that shifts in defence allocation under future climate change may not compromise herbivore resistance in wheat.  aECOLOGÍA  aCrop resistance  aGlobal change ecology  aPlant defence  aPlant–herbivore interactions1 aCIBILS-STEWART, X.1 aWATERMAN, J.M.1 aBIRU, F.N.1 aROWE, R.C.1 aHARTLEY, S.E.  tProceedings of the Royal Society B: Biological Sciences, 2022, Volume 289, Issue 1969, Article number 20212536. doi: https://doi.org/10.6084/m9.figshare.c.5833004