Climate change induced changes in wheat: Consequences for virus disease and biology of the insect vector

Background/Question/Methods

Since the beginning of the industrial revolution, as a consequence of population growth, increased use of fossil fuels has steadily increased atmospheric CO₂ concentrations. Currently, CO₂ levels are averaging at 400 µmol mol-¹ and are predicted to double by the end of this century. Climate change associated with elevated CO₂ (eCO₂) is having a significant impact on agroecosystems as it is influencing plant growth, nutrient concentration, yield and particularly can affect plant, pathogen and insect interactions. To better understand how climate change is affecting such interactions, we conducted a series of experiments in plant growth chambers and in the Australian Grains Free-Air CO₂ Enrichment (AGFACE) facilities in Horsham, Australia. We used Barley yellow dwarf virus (BYDV) and its aphid vector Rhopalosiphum padi, both of which cause substantial damage to wheat and other cereal crops worldwide. In the AGFACE facility, we examined BYDV-infected and noninfected wheat response to ambient and elevated CO₂ (550 µmol mol^-1) levels. We also investigated aphid fecundity and feeding behavior using an electrical penetration graph (EPG) method on BYDV-infected and noninfected plants grown under the ambient and elevated CO₂treatments.

Results/Conclusions

In both the plant growth chambers and AGFACE facilities, there was a significant effect of eCO₂ conditions on noninfected and BYDV-infected wheat plants. Plant biomass, tiller number, height and chlorophyll content increased in noninfected plants under eCO₂. Virus severity significantly increased in wheat grown under eCO₂, expressed by greater yield reduction and higher virus titer. Additionally, eCO₂ altered wheat biochemistry, increasing the carbon to nitrogen (C:N) ratio and, in turn affecting aphid biology and feeding behavior. R. padi fecundity significantly decreased on wheat due to eCO₂ although there was an increase in phloem ingestion. These findings have significant implications for understanding the occurrence and spread of BYDV and how crops will be affected under future climate conditions. Our study highlights potential ecological and epidemiological consequences of virus infection and crop production as our climate continues to change.