The impact of climate change on maize chemical defenses

Climate change is increasingly affecting agriculture, both at the levels of crops them-selves, and by altering the distribution and damage caused by insect or microbial pests. As global food security depends on the reliable production of major crops such as maize (Zea mays), it is vital that appropriate steps are taken to mitigate these negative impacts. To do this a clear understanding of what the impacts are and how they occur is needed. This review focuses on the impact of climate change on the production and effectiveness of maize chemical defenses, including volatile organic compounds, terpenoid phytoalex-ins, benzoxazinoids, phenolics, and flavonoids. Drought, flooding, heat stress, and ele-vated concentrations of atmospheric carbon dioxide, all impact the production of maize chemical defenses, in a compound and tissue-specific manner. Furthermore, changes in stomatal conductance and altered soil conditions caused by climate change can impact environmental dispersal and effectiveness certain chemicals. This can alter both defen-sive barrier formation and multitrophic interactions. The production of defense chemicals is controlled by stress signaling networks. The use of similar networks to co-ordinate the response to abiotic and biotic stress can lead to complex integration of these networks in response to the combinatorial stresses that are likely to occur in a changing climate. The impact of multiple stressors on maize chemical defenses can therefore be different from the sum of the responses to individual stressors and challenging to predict. Much work remains to effectively leverage these protective chemicals in climate-resilient maize.

Automated summary

Climate change has a significant impact on the production and effectiveness of maize chemical defenses, including the production of volatile organic compounds, terpenoid phytoalexins, benzoxazinoids, phenolics, and flavonoids. Drought, flooding, heat stress, and elevated carbon dioxide concentrations affect the production of these defense chemicals in a tissue-specific manner. Changes in stomatal conductance and altered soil conditions also impact the environmental dispersal and effectiveness of these chemicals, leading to complex interactions and challenges in predicting their response to multiple stressors. Further research is needed to effectively utilize these protective chemicals for climate-resilient maize.